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1.
The Utility of Interappendicular Connections in Bipedal Locomotion.
McMillan, D, de Leon, R, Guertin, PA, Dy, C
Current pharmaceutical design. 2017;(12):1734-1740
Abstract
Homo sapiens constitute the only currently obligate bipedal mammals and, as it stands, upright bipedal locomotion is a defining characteristic of humans. Indeed, while the evolution to bipedalism has allowed for the upper limbs to be liberated from ground contact during ambulation, their role in locomotion is far from obsolete. Rather, there is reason to believe that arm swing offers important mechanical and neurological advantages to bipedal locomotion. In this short review, we present some compelling findings on the neural connections between the arms and legs during human locomotion. We begin with a description of the importance of arm swing during walking from a mechanical perspective. Then, we examine evidence for the existence of interappendicular connections that converge along with peripheral afferents, descending inputs, and propriospinal projections, onto the neural circuits innervating the muscles of the arms and legs. The varied effects of interappendicular coupling on the neural control of locomotion are also examined in cases of neurological injury. We use the insight gained from these collected works as well as those from our own studies on locomotor training to discuss strategies to use interappendicular connections to rehabilitate walking in individuals experiencing loss of function after debilitating spinal cord injury.
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Involvement of the TRPV1 channel in the modulation of spontaneous locomotor activity, physical performance and physical exercise-induced physiological responses.
Hudson, AS, Kunstetter, AC, Damasceno, WC, Wanner, SP
Brazilian journal of medical and biological research = Revista brasileira de pesquisas medicas e biologicas. 2016;(6):e5183
Abstract
Physical exercise triggers coordinated physiological responses to meet the augmented metabolic demand of contracting muscles. To provide adequate responses, the brain must receive sensory information about the physiological status of peripheral tissues and organs, such as changes in osmolality, temperature and pH. Most of the receptors involved in these afferent pathways express ion channels, including transient receptor potential (TRP) channels, which are usually activated by more than one type of stimulus and are therefore considered polymodal receptors. Among these TRP channels, the TRPV1 channel (transient receptor potential vanilloid type 1 or capsaicin receptor) has well-documented functions in the modulation of pain sensation and thermoregulatory responses. However, the TRPV1 channel is also expressed in non-neural tissues, suggesting that this channel may perform a broad range of functions. In this review, we first present a brief overview of the available tools for studying the physiological roles of the TRPV1 channel. Then, we present the relationship between the TRPV1 channel and spontaneous locomotor activity, physical performance, and modulation of several physiological responses, including water and electrolyte balance, muscle hypertrophy, and metabolic, cardiovascular, gastrointestinal, and inflammatory responses. Altogether, the data presented herein indicate that the TPRV1 channel modulates many physiological functions other than nociception and thermoregulation. In addition, these data open new possibilities for investigating the role of this channel in the acute effects induced by a single bout of physical exercise and in the chronic effects induced by physical training.
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3.
[Fall risk and fracture. Locomotive syndrome and fall].
Ishibashi, H
Clinical calcium. 2013;(5):669-77
Abstract
Locomotive syndrome means a condition at a risk for requiring nursing care due to deteriorated musculoskeletal organs in the middle-aged and older people. Considering that this concept aims to care prevention and that fracture for fall consists of one-tenth of causes for requiring using care, fall prevention should be an important goal of preventing or improving locomotive syndrome. As a matter of fact, locomotion check - a short form for predicting locomotive syndrome- contains items evaluating fall risk, and locomotion training - recommended exercises designated for strengthening muscles of lower extremities and balance - likely to decrease future incidence of falls. Thus, locomotive syndrome seems to be deeply related to prevention of falls as well as care prevention.
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4.
Gait disorders.
Dietz, V
Handbook of clinical neurology. 2013;:133-43
Abstract
This chapter deals with the neuronal mechanisms underlying impaired gait. The aim is, first, a better understanding of the underlying pathophysiology and, second, the selection of an adequate treatment. One of the first symptoms of a lesion within the central motor system perceived by patients is a movement disorder, which is most characteristic during locomotion, e.g. in patients suffering spasticity after stroke or a spinal cord injury or Parkinson disease. By the recording and analysis of electrophysiological and biomechanical signals during a movement, the significance of impaired reflex behavior or muscle tone and its contribution to the movement disorder can reliably be assessed. Adequate treatment should not be restricted to the correction of an isolated clinical sign but should be based on the mechanisms underlying the movement disorder that impairs the patient. Therapy should be directed toward functional training, which takes advantage of the plasticity of the nervous system. In the future a combination of repair and functional training will further improve the mobility of disabled patients.
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5.
[Preventive and therapeutic approach to the locomotive syndrome].
Akune, T
Clinical calcium. 2013;(1):83-91
Abstract
The locomotive syndrome is a serious health condition that places the elderly at high risk of requiring support and long-term care caused by common age-related musculoskeletal disorders such as osteoporosis, osteoarthritis and sarcopenia. Accumulation of epidemiological evidence is required for the prevention strategy of the locomotive syndrome. Exercise intervention may be useful for the treatment of this condition.
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6.
Quadrupedal coordination of bipedal gait: implications for movement disorders.
Dietz, V
Journal of neurology. 2011;(8):1406-12
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Abstract
During recent years, evidence has come up that bipedal locomotion is based on a quadrupedal limb coordination. A task-dependent neuronal coupling of upper and lower limbs allows one to involve the arms during gait but to uncouple this connection during voluntarily guided arm/hand movements. Hence, despite the evolution of a strong cortico-spinal control of hand/arm movements in humans, a quadrupedal limb coordination persists during locomotion. This has consequences for the limb coordination in movement disorders such as in Parkinson's disease (PD) and after stroke. In patients suffering PD, the quadrupedal coordination of gait is basically preserved. The activation of upper limb muscles during locomotion is strong, similar as in age-matched healthy subjects although arm swing is reduced. This suggests a contribution of biomechanical constraints to immobility. In post-stroke subjects a close interactions between unaffected and affected sides with an impaired processing of afferent input takes place. An afferent volley applied to a leg nerve of the unaffected leg leads to a normal reflex activation of proximal arm muscles of both sides. In contrast, when the nerve of the affected leg was stimulated, neither on the affected nor in the unaffected arm muscles EMG responses appear. Muscle activation on the affected arm becomes normalized by influences of the unaffected side during locomotion. These observations have consequences for the rehabilitation of patients suffering movement disorders.
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Multiple sclerosis therapeutic pipeline: opportunities and challenges.
Krieger, S
The Mount Sinai journal of medicine, New York. 2011;(2):192-206
Abstract
The year 2010 marked the beginning of the era of oral medications for the treatment of multiple sclerosis, with the approval of dalfampridine to improve walking and fingolimod as the first oral disease-modifying agent. This review provides an overview of these and other emerging therapies, with an emphasis on the opportunities for new treatment paradigms they have the potential to offer, followed by a discussion of the challenges they will pose in the new era of multiple sclerosis management. Therapeutics in late-stage development for MS include non-selective immunosupressants, targeted immune-modulators, and monoclonal antibodies. Oral agents including cladribine, teriflunomide, laquinimod, and dimethyl fumarate, as well as monoclonal antibodies alemtuzumab, daclizumab, and rituximab are considered. Potential side effects and adverse event monitoring, including opportunistic infections, emergent malignancies, and other systemic consequences of immunosuppression are discussed in a unified section. Challenges of optimally staging, sequencing, and combining treatments in the expanding multiple sclerosis armamentarium are discussed. This review emphasizes the multifactorial decision making that these new therapeutics will warrant in terms of patient selection and personalization/individualization of therapy, and the increasingly interdisciplinary approach that will be necessitated by the new generation of agents.
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[Focus on current research: improving the mobility of paraplegic patients].
Dietz, V
Schweizerische medizinische Wochenschrift. 2000;(22):829-36
Abstract
Since the first paraplegic centre was established in 1945, life expectancy and life quality of paraplegics have considerably improved. However, endeavours to enhance the mobility of these patients have been less successful. The most promising approach, functional electric stimulation of paralysed muscles, is poorly accepted by patients at present because of technical problems. This study describes current approaches which may help to improve patients' mobility. A central motor lesion is perceived by the patient as a movement disorder of the legs, e.g. a gait disorder. Neurological investigation indicates, on the basis of exaggerated tendon reflexes and increased resistance of the non-activated leg muscles to stretching, that spastic paresis underlies the movement disorder. This combination of symptoms and clinical (physical) signs suggests that the exaggerated tendon tap reflexes are responsible for muscle hypertonia and the latter causes the movement disorder. However, electromyography during movement shows that the exaggerated short latency reflexes are associated with loss or attenuation of the functionally essential polysynaptic spinal reflexes. In the event of impaired supraspinal control there is loss of monosynaptic stretch reflex inhibition combined with reduced facilitation of polysynaptic spinal reflexes. Development of tension in tonically active calf muscles in patients with spastic paresis during gait occurs independently of spinal reflex activity. From electrophysiological and histological observations it can be assumed that transformation of motor units resulting in simple and less well adapted regulation of muscle tone allows movements such as gait. The reduction of muscle tone obtained with antispastic drugs is usually associated with paresis and may therefore hamper locomotion. Locomotor training represents a new attempt to improve the mobility of patients with incomplete paraplegia. It includes activation of neuronal circuits within the spinal cord below the level of the lesion. In incomplete paraplegics a coordinated leg muscle activation pattern and corresponding leg movements can be triggered and trained in patients standing on a treadmill with partial weight support. Improvement of training of the spinal cord locomotor centre can be expected from triggering of spinal cord reflexes and regeneration of spinal tract fibres, which is expected to be possible in the near future.