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1.
Eur J Neurosci ; 2024 Jun 09.
Artigo em Inglês | MEDLINE | ID: mdl-38853295

RESUMO

Heteronymous inhibition between lower limb muscles is primarily attributed to recurrent inhibitory circuits in humans but could also arise from Golgi tendon organs (GTOs). Distinguishing between recurrent inhibition and mechanical activation of GTOs is challenging because their heteronymous effects are both elicited by stimulation of nerves or a muscle above motor threshold. Here, the unique influence of mechanically activated GTOs was examined by comparing the magnitude of heteronymous inhibition from quadriceps (Q) muscle stimulation onto ongoing soleus electromyographic at five Q stimulation intensities (1.5-2.5× motor threshold) before and after an acute bout of stimulation-induced Q fatigue. Fatigue was used to decrease Q stimulation evoked force (i.e., decreased GTO activation) despite using the same pre-fatigue stimulation currents (i.e., same antidromic recurrent inhibition input). Thus, a decrease in heteronymous inhibition after Q fatigue and a linear relation between stimulation-evoked torque and inhibition both before and after fatigue would support mechanical activation of GTOs as a source of inhibition. A reduction in evoked torque but no change in inhibition would support recurrent inhibition. After fatigue, Q stimulation-evoked knee torque, heteronymous inhibition magnitude and inhibition duration were significantly decreased for all stimulation intensities. In addition, heteronymous inhibition magnitude was linearly related to twitch-evoked knee torque before and after fatigue. These findings support mechanical activation of GTOs as a source of heteronymous inhibition along with recurrent inhibition. The unique patterns of heteronymous inhibition before and after fatigue across participants suggest the relative contribution of GTOs, and recurrent inhibition may vary across persons.

2.
Vet Pathol ; 60(4): 420-433, 2023 07.
Artigo em Inglês | MEDLINE | ID: mdl-37199487

RESUMO

Chronic wasting disease (CWD) is an infectious transmissible spongiform encephalopathy of cervids associated with the presence of a misfolded prion protein (PrPCWD). Progression of PrPCWD distribution has been described using immunohistochemistry and histologic changes in a single section of brain stem at the level of the obex resulting in scores from 0 (early) to 10 (terminal) in elk with naturally occurring CWD. Here we describe the spread and distribution of PrPCWD in peripheral tissues and spinal cord in 16 wild and 17 farmed Rocky Mountain elk (Cervus elaphus nelsoni) with naturally occurring CWD and correlate these findings with obex scores. Spinal cord and approximately 110 peripheral tissues were collected, processed, stained with hematoxylin and eosin, and immunolabeled with the anti-prion protein monoclonal antibody F99/97.6.1. The medial retropharyngeal and tracheobronchial lymph nodes were the first tissues to accumulate PrPCWD, followed by other lymphoid tissues, myenteric plexus, spinal cord, and finally tissues outside of the lymphatic and neural systems. However, the only significant histological lesion observed was mild spongiform encephalopathy in the dorsal column of the lower spinal cord in elk with an obex score of ≥9. Initial exposure to CWD prions may be through the respiratory system and spread appears to occur primarily via the autonomic nervous system. Therefore, we suggest using obex scores as a proxy for stage of disease progression and verifying with key peripheral tissues.


Assuntos
Cervos , Doenças Priônicas , Príons , Doença de Emaciação Crônica , Animais , Doença de Emaciação Crônica/patologia , Proteínas Priônicas , Doenças Priônicas/veterinária , Medula Espinal/patologia , Isoformas de Proteínas/metabolismo
4.
Mol Psychiatry ; 27(10): 4001-4008, 2022 10.
Artigo em Inglês | MEDLINE | ID: mdl-35879401

RESUMO

Alcohol's impact on telomere length, a proposed marker of biological aging, is unclear. We performed the largest observational study to date (in n = 245,354 UK Biobank participants) and compared findings with Mendelian randomization (MR) estimates. Two-sample MR used data from 472,174 participants in a recent genome-wide association study (GWAS) of telomere length. Genetic variants were selected on the basis of associations with alcohol consumption (n = 941,280) and alcohol use disorder (AUD) (n = 57,564 cases). Non-linear MR employed UK Biobank individual data. MR analyses suggested a causal relationship between alcohol traits, more strongly for AUD, and telomere length. Higher genetically-predicted AUD (inverse variance-weighted (IVW) ß = -0.06, 95% confidence interval (CI): -0.10 to -0.02, p = 0.001) was associated with shorter telomere length. There was a weaker association with genetically-predicted alcoholic drinks weekly (IVW ß = -0.07, CI: -0.14 to -0.01, p = 0.03). Results were consistent across methods and independent from smoking. Non-linear analyses indicated a potential threshold relationship between alcohol and telomere length. Our findings indicate that alcohol consumption may shorten telomere length. There are implications for age-related diseases.


Assuntos
Estudo de Associação Genômica Ampla , Análise da Randomização Mendeliana , Humanos , Polimorfismo de Nucleotídeo Único , Consumo de Bebidas Alcoólicas/genética , Etanol , Telômero/genética
5.
Exp Brain Res ; 239(9): 2679-2691, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34218298

RESUMO

Successful propagation throughout the step cycle is contingent on adequate regulation of whole-limb stiffness by proprioceptive feedback. Following spinal cord injury (SCI), there are changes in the strength and organization of proprioceptive feedback that can result in altered joint stiffness. In this study, we measured changes in autogenic feedback of five hindlimb extensor muscles following chronic low thoracic lateral hemisection (LSH) in decerebrate cats. We present three features of the autogenic stretch reflex obtained using a mechanographic method. Stiffness was a measure of the resistance to stretch during the length change. The dynamic index documented the extent of adaptation or increase of the force response during the hold phase, and the impulse measured the integral of the response from initiation of a stretch to the return to the initial length. The changes took the form of variable and transient increases in the stiffness of vastus (VASTI) group, soleus (SOL), and flexor hallucis longus (FHL), and either increased (VASTI) or decreased adaptation (GAS and PLANT). The stiffness of the gastrocnemius group (GAS) was also variable over time but remained elevated at the final time point. An unexpected finding was that these effects were observed bilaterally. Potential reasons for this finding and possible sources of increased excitability to this muscle group are discussed.


Assuntos
Reflexo de Estiramento , Traumatismos da Medula Espinal , Animais , Estado de Descerebração , Membro Posterior , Músculo Esquelético , Reflexo , Regulação para Cima
6.
Int J Behav Nutr Phys Act ; 18(1): 47, 2021 03 31.
Artigo em Inglês | MEDLINE | ID: mdl-33789683

RESUMO

BACKGROUND: Physical activity (PA) may positively stimulate the brain, cognition and mental health during adolescence, a period of dynamic neurobiological development. High-intensity interval training (HIIT) or vigorous PA interventions are time-efficient, scalable and can be easily implemented in existing school curricula, yet their effects on cognitive, academic and mental health outcomes are unclear. The primary aim of the Fit to Study trial was to investigate whether a pragmatic and scalable HIIT-style VPA intervention delivered during school physical education (PE) could improve attainment in maths. The primary outcome has previously been reported and was null. Here, we report the effect of the intervention on prespecified secondary outcomes, including cardiorespiratory fitness, cognitive performance, and mental health in young adolescents. METHODS: The Fit to Study cluster randomised controlled trial included Year 8 pupils (n = 18,261, aged 12-13) from 104 secondary state schools in South/Mid-England. Schools were randomised into an intervention condition (n = 52), in which PE teachers delivered an additional 10 min of VPA per PE lesson for one academic year (2017-2018), or into a "PE as usual" control condition. Secondary outcomes included assessments of cardiorespiratory fitness (20-m shuttle run), cognitive performance (executive functions, relational memory and processing speed) and mental health (Strength and Difficulties Questionnaire and self-esteem measures). The primary intention-to-treat (ITT) analysis used linear models and structural equation models with cluster-robust standard errors to test for intervention effects. A complier-average causal effect (CACE) was estimated using a two-stage least squares procedure. RESULTS: The HIIT-style VPA intervention did not significantly improve cardiorespiratory fitness, cognitive performance (executive functions, relational memory or processed speed), or mental health (all p > 0.05). Subgroup analyses showed no significant moderation of intervention effects by sex, socioeconomic status or baseline fitness levels. Changes in cardiorespiratory fitness were not significantly related to changes in cognitive or mental health outcomes. The trial was marked by high drop-out and low intervention compliance. Findings from the CACE analysis were in line with those from the ITT analysis. CONCLUSION: The one-academic year HIIT-style VPA intervention delivered during regular school PE did not significantly improve fitness, cognitive performance or mental health, but these findings should be interpreted with caution given low implementation fidelity and high drop-out. Well-controlled, large-scale, school-based trials that examine the effectiveness of HIIT-style interventions to enhance cognitive and mental health outcomes are warranted. TRIAL REGISTRATION: ISRCTN registry, 15,730,512 . Trial protocol and analysis plan for primary outcome prospectively registered on 30th March 2017. ClinicalTrials.gov , NCT03286725 . Secondary measures (focus of current manuscript) retrospectively registered on 18 September 2017.


Assuntos
Desempenho Acadêmico , Aptidão Cardiorrespiratória , Exercício Físico , Matemática , Saúde Mental , Processos Mentais , Adolescente , Encéfalo/fisiologia , Cognição , Inglaterra , Função Executiva , Treinamento Intervalado de Alta Intensidade , Humanos , Masculino , Educação Física e Treinamento
8.
J Neurosci Res ; 98(8): 1646-1661, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32537945

RESUMO

Inhibitory pathways from Golgi tendon organs project widely between muscles crossing different joints and axes of rotation. Evidence suggests that the strength and distribution of this intermuscular inhibition is dependent on motor task and corresponding signals from the brainstem. The purpose of the present study was to investigate whether this sensory network is altered after spinal cord hemisection as a potential explanation for motor deficits observed after spinal cord injury (SCI). Force feedback was assessed between the long toe flexor and ankle plantarflexor (flexor hallucis longus), and the three major ankle extensors, (combined gastrocnemius, soleus, and plantaris muscles) in the hind limbs of unanesthetized, decerebrate, female cats. Data were collected from animals with intact spinal cords (control) and lateral spinal hemisections (LSHs) including chronic LSH (4-20 weeks), subchronic LSH (2 weeks), and acute LSH. Muscles were stretched individually and in pairwise combinations to measure intermuscular feedback between the toe flexor and each of the ankle extensors. In control animals, three patterns were observed (balanced inhibition between toe flexor and ankle extensors, stronger inhibition from toe flexor to ankle extensor, and vice versa). Following spinal hemisection, only strong inhibition from toe flexors onto ankle extensors was observed independent of survival time. The results suggest immediate and permanent reorganization of force feedback in the injured spinal cord. The altered strength and distribution of force feedback after SCI may be an important future target for rehabilitation.


Assuntos
Tornozelo , Músculo Esquelético/fisiologia , Traumatismos da Medula Espinal , Dedos do Pé , Animais , Gatos , Feminino , Membro Posterior , Reflexo/fisiologia , Medula Espinal
9.
J Neurophysiol ; 123(1): 70-89, 2020 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-31693435

RESUMO

Sensorimotor training providing motion-dependent somatosensory feedback to spinal locomotor networks restores treadmill weight-bearing stepping on flat surfaces in spinal cats. In this study, we examined if locomotor ability on flat surfaces transfers to sloped surfaces and the contribution of length-dependent sensory feedback from lateral gastrocnemius (LG) and soleus (Sol) to locomotor recovery after spinal transection and locomotor training. We compared kinematics and muscle activity at different slopes (±10° and ±25°) in spinalized cats (n = 8) trained to walk on a flat treadmill. Half of those animals had their right hindlimb LG/Sol nerve cut and reattached before spinal transection and locomotor training, a procedure called muscle self-reinnervation that leads to elimination of autogenic monosynaptic length feedback in spinally intact animals. All spinal animals trained on a flat surface were able to walk on slopes with minimal differences in walking kinematics and muscle activity between animals with/without LG/Sol self-reinnervation. We found minimal changes in kinematics and muscle activity at lower slopes (±10°), indicating that walking patterns obtained on flat surfaces are robust enough to accommodate low slopes. Contrary to results in spinal intact animals, force responses to muscle stretch largely returned in both SELF-REINNERVATED muscles for the trained spinalized animals. Overall, our results indicate that the locomotor patterns acquired with training on a level surface transfer to walking on low slopes and that spinalization may allow the recovery of autogenic monosynaptic length feedback following muscle self-reinnervation.NEW & NOTEWORTHY Spinal locomotor networks locomotor trained on a flat surface can adapt the locomotor output to slope walking, up to ±25° of slope, even with total absence of supraspinal CONTROL. Autogenic length feedback (stretch reflex) shows signs of recovery in spinalized animals, contrary to results in spinally intact animals.


Assuntos
Adaptação Fisiológica/fisiologia , Retroalimentação Sensorial/fisiologia , Membro Posterior/inervação , Músculo Esquelético/inervação , Rede Nervosa/fisiopatologia , Recuperação de Função Fisiológica/fisiologia , Traumatismos da Medula Espinal/fisiopatologia , Transferência de Experiência/fisiologia , Caminhada/fisiologia , Animais , Comportamento Animal/fisiologia , Fenômenos Biomecânicos , Gatos , Feminino , Prática Psicológica , Reflexo de Estiramento/fisiologia
10.
J Physiol ; 597(17): 4627-4642, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31228207

RESUMO

KEY POINTS: Golgi tendon organ feedback has been evaluated most frequently using electrical stimulation of peripheral nerves, which is not a physiological or selective stimulus for Golgi tendon organs. Golgi tendon organs are most responsive to active muscle contractions. This study provides evidence that muscle stimulation evoked twitches - a physiological stimulus for Golgi tendon organs - induces intermuscular effects most likely due to mechanical activation of Golgi tendon organ feedback and not direct activation of sensory axons. The results demonstrate that twitch contractions are a feasible non-invasive approach that can be used to advance understanding of the functional role of Golgi tendon organ feedback. ABSTRACT: Force feedback from Golgi tendon organs (GTOs) has widespread intermuscular projections mediated by interneurons that share inputs from muscle spindles, among others. Because current methods to study GTO circuitry (nerve stimulation or muscle stretch) also activate muscle spindle afferents, the selective role of GTOs remains uncertain. Here, we tested the hypothesis that intramuscular stimulation evoked twitch contractions could be used to naturally bias activation of GTOs and thus evaluate their intermuscular effects in decerebrate cats. This was achieved by comparing the effects of twitch contractions and stretches as donor inputs onto the motor output of recipient muscles. Donor-recipient pairs evaluated included those already known in the cat to receive donor excitatory muscle spindle feedback only, inhibitory GTO feedback only, and both excitatory spindle and inhibitory GTO effects. Muscle stretch, but not twitch contractions, evoked excitation onto recipient muscles with muscle spindle afferent inputs only. Both donor muscle stretch and twitch contractions inhibited a recipient muscle with GTO projections only. In a recipient muscle that receives both muscle spindle and GTO projections, donor muscle stretch evoked both excitatory and inhibitory effects, whereas twitch contractions evoked inhibitory effects only. These data support the hypothesis that muscle stimulation evoked contractions can induce intermuscular effects most consistent with mechanical GTO receptor activation and not direct activation of sensory axons. We propose this approach can be used to evaluate GTO circuitry more selectively than muscle stretch or nerve stimulation and can be adapted to study GTO feedback non-invasively in freely moving cats and humans.


Assuntos
Mecanorreceptores/fisiologia , Contração Muscular/fisiologia , Animais , Axônios/fisiologia , Gatos , Estimulação Elétrica/métodos , Retroalimentação , Fusos Musculares/fisiologia , Músculo Esquelético/fisiologia , Células Receptoras Sensoriais/fisiologia
11.
J Neurophysiol ; 119(3): 1186-1200, 2018 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-29212914

RESUMO

This review is an update on the role of force feedback from Golgi tendon organs in the regulation of limb mechanics during voluntary movement. Current ideas about the role of force feedback are based on modular circuits linking idealized systems of agonists, synergists, and antagonistic muscles. In contrast, force feedback is widely distributed across the muscles of a limb and cannot be understood based on these circuit motifs. Similarly, muscle architecture cannot be understood in terms of idealized systems, since muscles cross multiple joints and axes of rotation and further influence remote joints through inertial coupling. It is hypothesized that distributed force feedback better represents the complex mechanical interactions of muscles, including the stresses in the musculoskeletal network born by muscle articulations, myofascial force transmission, and inertial coupling. Together with the strains of muscle fascicles measured by length feedback from muscle spindle receptors, this integrated proprioceptive feedback represents the mechanical state of the musculoskeletal system. Within the spinal cord, force feedback has excitatory and inhibitory components that coexist in various combinations based on motor task and integrated with length feedback at the premotoneuronal and motoneuronal levels. It is concluded that, in agreement with other investigators, autogenic, excitatory force feedback contributes to propulsion and weight support. It is further concluded that coexistent inhibitory force feedback, together with length feedback, functions to manage interjoint coordination and the mechanical properties of the limb in the face of destabilizing inertial forces and positive force feedback, as required by the accelerations and changing directions of both predator and prey.


Assuntos
Extremidades/fisiologia , Retroalimentação Fisiológica , Mecanorreceptores/fisiologia , Músculo Esquelético/fisiologia , Medula Espinal/fisiologia , Animais , Extremidades/inervação , Humanos , Vias Neurais , Propriocepção/fisiologia , Estresse Mecânico
12.
J Neurophysiol ; 119(2): 668-678, 2018 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-29142095

RESUMO

Prior work has suggested that Golgi tendon organ feedback, via its distributed network linking muscles spanning all joints, could be used by the nervous system to help regulate whole limb mechanics if appropriately organized. We tested this hypothesis by characterizing the patterns of intermuscular force-dependent feedback between the primary extensor muscles spanning the knee, ankle, and toes in decerebrate cat hindlimbs. Intermuscular force feedback was evaluated by stretching tendons of selected muscles in isolation and in pairwise combinations and then measuring the resulting force-dependent intermuscular interactions. The relative inhibitory feedback between extensor muscles was examined, as well as symmetry of the interactions across limbs. Differences in the directional biases of inhibitory feedback were observed across cats, with three patterns identified as points on a spectrum: pattern 1, directional bias of inhibitory feedback onto the ankle extensors and toe flexors; pattern 2, convergence of inhibitory feedback onto ankle extensors and mostly balanced inhibitory feedback between vastus muscle group and flexor hallucis longus, and pattern 3, directional bias of inhibitory feedback onto ankle and knee extensors. The patterns of inhibitory feedback, while different across cats, were symmetric across limbs of individual cats. The variable but structured distribution of force feedback across cat hindlimbs provides preliminary evidence that inhibitory force feedback could be a regulated neural control variable. We propose the directional biases of inhibitory feedback observed experimentally could provide important task-dependent benefits, such as directionally appropriate joint compliance, joint coupling, and compensation for nonuniform inertia. NEW & NOTEWORTHY Feedback from Golgi tendon organs project widely among extensor motor nuclei in the spinal cord. The distributed nature of force feedback suggests these pathways contribute to the global regulation of limb mechanics. Analysis of this network in individual animals indicates that the strengths of these pathways can be reorganized appropriately for a variety of motor tasks, including level walking, slope walking, and landing.


Assuntos
Retroalimentação Fisiológica , Membro Posterior/fisiologia , Músculo Esquelético/fisiologia , Inibição Neural , Animais , Fenômenos Biomecânicos , Gatos , Feminino , Membro Posterior/inervação , Mecanorreceptores/fisiologia , Medula Espinal/fisiologia
13.
Physiol Rep ; 5(9)2017 May.
Artigo em Inglês | MEDLINE | ID: mdl-28468849

RESUMO

Tendon transfer surgeries are performed to restore lost motor function, but outcomes are variable, particularly those involving agonist-to-antagonist muscles. Here, we evaluated the possibility that lack of proprioceptive feedback reorganization and musculotendon adaptations could influence outcomes. Plantaris-to-tibialis anterior tendon transfer along with resection of the distal third of the tibialis anterior muscle belly was performed in eight cats. Four cats had concurrent transection of the deep peroneal nerve. After 15-20 weeks, intermuscular length and force-dependent sensory feedback were examined between hindlimb muscles, and the integrity of the tendon-to-tendon connection and musculotendon adaptations were evaluated. Three of the transferred tendons tore. A common finding was the formation of new tendinous connections, which often inserted near the original location of insertion on the skeleton (e.g., connections from plantaris toward calcaneus and from tibialis anterior toward first metatarsal). The newly formed tissue connections are expected to compromise the mechanical action of the transferred muscle. We found no evidence of changes in intermuscular reflexes between transferred plantaris muscle and synergists/antagonists whether the tendon-to-tendon connection remained intact or tore, indicating no spinal reflex reorganization. We propose the lack of spinal reflex reorganization could contribute the transferred muscle not adopting the activation patterns of the host muscle. Taken together, these findings suggest that musculotendon plasticity and lack of spinal reflex circuitry reorganization could limit functional outcomes after tendon transfer surgery. Surgical planning and outcomes assessments after tendon transfer surgery should consider potential consequences of the transferred muscle's intermuscular spinal circuit actions.


Assuntos
Retroalimentação Fisiológica , Músculo Esquelético/fisiologia , Reflexo , Medula Espinal/fisiologia , Tendões/fisiologia , Animais , Gatos , Vias Eferentes/fisiologia , Feminino , Músculo Esquelético/inervação , Nervo Fibular/fisiologia
14.
Atherosclerosis ; 258: 40-50, 2017 03.
Artigo em Inglês | MEDLINE | ID: mdl-28189040

RESUMO

BACKGROUND AND AIMS: Diabetes is a major risk factor for the development of atherosclerosis. Hyperglycemia stimulates vascular smooth muscle cells (VSMC) to secrete ligands that bind to the αVß3 integrin, a receptor that regulates VSMC proliferation and migration. This study determined whether an antibody that had previously been shown to block αVß3 activation and to inhibit VSMC proliferation and migration in vitro, inhibited the development of atherosclerosis in diabetic pigs. METHODS: Twenty diabetic pigs were maintained on a high fat diet for 22 weeks. Ten received injections of anti-ß3 F(ab)2 and ten received control F(ab)2 for 18 weeks. RESULTS: The active antibody group showed reduction of atherosclerosis of 91 ± 9% in the left main, 71 ± 11%, in left anterior descending, 80 ± 10.2% in circumflex, and 76 ± 25% in right coronary artery, (p < 0.01 compared to lesions areas from corresponding control treated arteries). There were significant reductions in both cell number and extracellular matrix. Histologic analysis showed neointimal hyperplasia with macrophage infiltration, calcifications and cholesterol clefts. Antibody treatment significantly reduced number of macrophages contained within lesions, suggesting that this change contributed to the decrease in lesion cellularity. Analysis of the biochemical changes within the femoral arteries that received the active antibody showed a 46 ± 12% (p < 0.05) reduction in the tyrosine phosphorylation of the ß3 subunit of αVß3 and a 40 ± 14% (p < 0.05) reduction in MAP kinase activation. CONCLUSIONS: Blocking ligand binding to the αVß3 integrin inhibits its activation and attenuates increased VSMC proliferation that is induced by chronic hyperglycemia. These changes result in significant decreases in atherosclerotic lesion size in the coronary arteries. The results suggest that this approach may have efficacy in treating the proliferative phase of atherosclerosis in patients with diabetes.


Assuntos
Doença da Artéria Coronariana/prevenção & controle , Diabetes Mellitus Experimental/tratamento farmacológico , Angiopatias Diabéticas/prevenção & controle , Fragmentos Fab das Imunoglobulinas/farmacologia , Integrina alfaVbeta3/antagonistas & inibidores , Músculo Liso Vascular/efeitos dos fármacos , Animais , Proliferação de Células/efeitos dos fármacos , Doença da Artéria Coronariana/etiologia , Doença da Artéria Coronariana/metabolismo , Vasos Coronários/efeitos dos fármacos , Vasos Coronários/metabolismo , Vasos Coronários/patologia , Diabetes Mellitus Experimental/complicações , Diabetes Mellitus Experimental/metabolismo , Angiopatias Diabéticas/etiologia , Angiopatias Diabéticas/metabolismo , Artéria Femoral/efeitos dos fármacos , Artéria Femoral/metabolismo , Artéria Femoral/patologia , Fragmentos Fab das Imunoglobulinas/administração & dosagem , Injeções Subcutâneas , Integrina alfaVbeta3/imunologia , Integrina alfaVbeta3/metabolismo , Ligantes , Macrófagos/efeitos dos fármacos , Macrófagos/metabolismo , Masculino , Músculo Liso Vascular/metabolismo , Músculo Liso Vascular/patologia , Neointima , Fosforilação , Placa Aterosclerótica , Ligação Proteica , Sus scrofa
15.
IEEE Trans Neural Syst Rehabil Eng ; 25(9): 1440-1452, 2017 09.
Artigo em Inglês | MEDLINE | ID: mdl-28113946

RESUMO

We have developed a stretchablemicroneedle electrode array (sMEA) to stimulate andmeasure the electrical activity of muscle across multiple sites. The technology provides the signal fidelity and spatial resolution of intramuscular electrodesacross a large area of tissue. Our sMEA is composed of a polydimethylsiloxane (PDMS) substrate, conductive-PDMS traces, and stainless-steel penetrating electrodes. The traces and microneedles maintain a resistance of less than 10 [Formula: see text] when stretched up to a ~63% tensile strain, which allows for the full range of physiological motion of felinemuscle. The device and its constituent materials are cytocompatible for at least 28 days in vivo. When implanted in vivo, the device measures electromyographic (EMG) activity with clear compound motor unit action potentials. The sMEA also maintains a stable connection with moving muscle while electrically stimulating the tissue. This technology has direct application to wearable sensors, neuroprostheses, and electrophysiological studies of animals and humans.


Assuntos
Estimulação Elétrica/instrumentação , Eletrodos Implantados , Eletromiografia/instrumentação , Microeletrodos , Fibras Musculares Esqueléticas/fisiologia , Agulhas , Potenciais de Ação/fisiologia , Animais , Células Cultivadas , Módulo de Elasticidade , Impedância Elétrica , Desenho de Equipamento , Análise de Falha de Equipamento , Humanos , Análise em Microsséries/instrumentação , Neurônios Motores/fisiologia , Contração Muscular/fisiologia , Ratos , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Transmissão Sináptica/fisiologia , Resistência à Tração
16.
J Neurophysiol ; 116(3): 1055-67, 2016 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-27306676

RESUMO

In this study, we sought to identify sensory circuitry responsible for motor deficits or compensatory adaptations after peripheral nerve cut and repair. Self-reinnervation of the ankle extensor muscles abolishes the stretch reflex and increases ankle yielding during downslope walking, but it remains unknown whether this finding generalizes to other muscle groups and whether muscles become completely deafferented. In decerebrate cats at least 19 wk after nerve cut and repair, we examined the influence of quadriceps (Q) muscles' self-reinnervation on autogenic length feedback, as well as intermuscular length and force feedback, among the primary extensor muscles in the cat hindlimb. Effects of gastrocnemius and soleus self-reinnervation on intermuscular circuitry were also evaluated. We found that autogenic length feedback was lost after Q self-reinnervation, indicating that loss of the stretch reflex appears to be a generalizable consequence of muscle self-reinnervation. However, intermuscular force and length feedback, evoked from self-reinnervated muscles, was preserved in most of the interactions evaluated with similar relative inhibitory or excitatory magnitudes. These data indicate that intermuscular spinal reflex circuitry has the ability to regain functional connectivity, but the restoration is not absolute. Explanations for the recovery of intermuscular feedback are discussed, based on identified mechanisms responsible for lost autogenic length feedback. Functional implications, due to permanent loss of autogenic length feedback and potential for compensatory adaptations from preserved intermuscular feedback, are discussed.


Assuntos
Retroalimentação Sensorial/fisiologia , Músculo Esquelético/fisiologia , Traumatismos dos Nervos Periféricos/fisiopatologia , Traumatismos dos Nervos Periféricos/cirurgia , Recuperação de Função Fisiológica/fisiologia , Reflexo de Estiramento/fisiologia , Animais , Articulação do Tornozelo/inervação , Gatos , Modelos Animais de Doenças , Eletromiografia , Potencial Evocado Motor/fisiologia , Feminino , Membro Posterior/inervação , Membro Posterior/fisiopatologia , Contração Muscular , Músculo Esquelético/lesões , Músculo Esquelético/cirurgia
17.
J Thromb Haemost ; 14(5): 894-905, 2016 05.
Artigo em Inglês | MEDLINE | ID: mdl-26924758

RESUMO

Animal models of inherited bleeding disorders are important for understanding disease pathophysiology and are required for preclinical assessment of safety prior to testing of novel therapeutics in human and veterinary medicine. Experiments in these animals represent important translational research aimed at developing safer and better treatments, such as plasma-derived and recombinant protein replacement therapies, gene therapies and immune tolerance protocols for antidrug inhibitory antibodies. Ideally, testing is done in animals with the analogous human disease to provide essential safety information, estimates of the correct starting dose and dose response (pharmacokinetics) and measures of efficacy (pharmacodynamics) that guide the design of human trials. For nearly seven decades, canine models of hemophilia, von Willebrand disease and other inherited bleeding disorders have not only informed our understanding of the natural history and pathophysiology of these disorders but also guided the development of novel therapeutics for use in humans and dogs. This has been especially important for the development of gene therapy, in which unique toxicities such as insertional mutagenesis, germ line gene transfer and viral toxicities must be assessed. There are several issues regarding comparative medicine in these species that have a bearing on these studies, including immune reactions to xenoproteins, varied metabolism or clearance of wild-type and modified proteins, and unique tissue tropism of viral vectors. This review focuses on the results of studies that have been performed in dogs with inherited bleeding disorders that closely mirror the human condition to develop safe and effective protein and gene-based therapies that benefit both species.


Assuntos
Modelos Animais de Doenças , Terapia Genética/efeitos adversos , Terapia Genética/métodos , Hemofilia A/terapia , Animais , Cães , Técnicas de Transferência de Genes , Vetores Genéticos , Mutação em Linhagem Germinativa , Hemofilia A/sangue , Hemofilia A/imunologia , Hemorragia/imunologia , Humanos , Tolerância Imunológica , Camundongos , Mutagênese , Primatas , Proteínas Recombinantes/química , Doenças de von Willebrand/imunologia
18.
J Air Waste Manag Assoc ; 66(1): 17-27, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26479121

RESUMO

UNLABELLED: The Bio-response Operational Testing and Evaluation (BOTE) Project was a cross-government effort designed to operationally test and evaluate a response to a biological incident (release of Bacillus anthracis [Ba] spores, the causative agent for anthrax) from initial public health and law enforcement response through environmental remediation. The BOTE Project was designed to address site remediation after the release of a Ba simulant, Bacillus atrophaeus spp. globigii (Bg), within a facility, drawing upon recent advances in the biological sampling and decontamination areas. A key component of response to a biological contamination incident is the proper management of wastes and residues, which is woven throughout all response activities. Waste is generated throughout the response and includes items like sampling media packaging materials, discarded personal protective equipment, items removed from the facility either prior to or following decontamination, aqueous waste streams, and materials generated through the application of decontamination technologies. The amount of residual contaminating agent will impact the available disposal pathways and waste management costs. Waste management is an integral part of the decontamination process and should be included through "Pre-Incident" response planning. Overall, the pH-adjusted bleach decontamination process generated the most waste from the decontamination efforts, and fumigation with chlorine dioxide generated the least waste. A majority of the solid waste generated during pH-adjusted bleach decontamination was the nonporous surfaces that were removed, bagged, decontaminated ex situ, and treated as waste. The waste during the two fumigation rounds of the BOTE Project was associated mainly with sampling activities. Waste management activities may represent a significant contribution to the overall cost of the response/recovery operation. This paper addresses the waste management activities for the BOTE field test. IMPLICATIONS: Management of waste is a critical element of activities dealing with remediation of buildings and outdoor areas following a biological contamination incident. Waste management must be integrated into the overall remediation process, along with sampling, decontamination, resource management, and other important response elements, rather than being a stand-alone activity. The results presented in this paper will provide decision makers and emergency planners at the federal/state/tribal/local level information that can be used to integrate waste management into an overall systems approach to planning and response activities.


Assuntos
Poluição do Ar em Ambientes Fechados , Descontaminação , Eliminação de Resíduos/métodos , Esporos Bacterianos/fisiologia , Derramamento de Material Biológico/prevenção & controle , Compostos Clorados , Desinfetantes/química , Desinfetantes/farmacologia , Contaminação de Equipamentos/prevenção & controle , Peróxido de Hidrogênio , Concentração de Íons de Hidrogênio , Óxidos , Hipoclorito de Sódio
20.
J Vet Intern Med ; 29(3): 908-16, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25871966

RESUMO

BACKGROUND: Studies of some human prothrombotic diseases suggest that phosphatidylserine-positive (PS+) and tissue factor-positive (TF+) microparticles (MPs) might play a role in the pathogenesis of thrombosis or serve as biomarkers of thrombotic risk. HYPOTHESIS/OBJECTIVES: To determine if circulating levels of PS+MP and procoagulant activity (PCA) associated with PS+MPs and TF+ MPs are increased in dogs with IMHA. ANIMALS: Fifteen dogs with primary or secondary IMHA and 17 clinically healthy dogs. METHODS: Prospective case-controlled observational study. Circulating PS+MPs were measured by flow cytometry. PCA associated with PS+MPs and TF+MPs was measured by thrombin and Factor Xa generating assays, respectively. RESULTS: Circulating numbers of PS+MPs were not significantly higher in dogs with IMHA [control median 251,000/µL (36,992-1,141,250/µL); IMHA median 361,990/µL (21,766-47,650,600/µL) P = .30]. However, PS+MP PCA [control median 2.2 (0.0-16.8) nM PS eq; IMHA median 8.596, (0-49.33 nM PS eq) P = .01] and TF+MP PCA [control median 0.0, (0.0-0.0 pg/mL); IMHA median 0.0; (0-22.34 pg/mL], P = .04) were increased. Intravascular hemolysis, which we showed might increase PS+ and TF+MP PCA, was evident in 3 of 5 dogs with PS+MP PCA and 2 of 4 dogs with TF+MP PCA higher than controls. Underlying disease in addition to IMHA was detected in 1 of 5 dogs with PS+PCA and 3 of 4 dogs with TF+MP PCA higher than controls. CONCLUSIONS AND CLINICAL IMPORTANCE: TF+ and PS+MP PCA is increased in some dogs with IMHA. Further studies that determine if measuring TF+ and PS+ MP PCA can help identify dogs at risk for thrombosis are warranted.


Assuntos
Anemia Hemolítica Autoimune/veterinária , Coagulantes/uso terapêutico , Doenças do Cão/tratamento farmacológico , Anemia Hemolítica Autoimune/tratamento farmacológico , Animais , Testes de Coagulação Sanguínea/veterinária , Estudos de Casos e Controles , Coagulantes/administração & dosagem , Cães , Feminino , Citometria de Fluxo , Hematócrito/veterinária , Masculino , Memória Episódica , Microesferas
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