The role of the deep cervical extensor muscles in multi-directional isometric neck strength.

Clinical management of whiplash-associated disorders is challenging and often unsuccessful, with over a third of whiplash injuries progressing to chronic neck pain. Previous imaging studies have identified muscle fat infiltration, indicative of muscle weakness, in the deep cervical extensor muscles (multifidus and semispinalis cervicis). Yet, kinematic and muscle redundancy prevent the direct assessment of individual neck muscle strength, making it difficult to determine the role of these muscles in motor dysfunction.

A Method for Quantification of Stretch Reflex Excitability During Ballistic Reaching.

Stretch reflexes are crucial for performing accurate movements and providing rapid corrections for unpredictable perturbations. Stretch reflexes are modulated by supraspinal structures via corticofugal pathways. Neural activity in these structures is difficult to observe directly, but the characterization of reflex excitability during volitional movement can be used to study how these structures modulate reflexes and how neurological injuries impact this control, such as in spasticity after stroke.

A Method for Quantifying Trunk Motor Control During Reaching in Individuals Post Hemiparetic Stroke.

After a hemiparetic stroke, the contralesional upper limb is left with significant motor impairments including: weakness, spasticity, and abnormal joint torque patterns resulting in the flexion synergy (i.e. abnormal coupling between shoulder abduction and elbow/wrist and finger flexion).

Ergodicity Reveals Assistance and Learning from Physical Human-Robot Interaction.

This paper applies information theoretic principles to the investigation of physical human-robot interaction. Drawing from the study of human perception and neural encoding, information theoretic approaches offer a perspective that enables quantitatively interpreting the body as an information channel, and bodily motion as an information-carrying signal. We show that ergodicity, which can be interpreted as the degree to which a trajectory encodes information about a task, correctly predicts changes due to reduction of a person's existing deficit or the addition of algorithmic assistance.

Otomyiasis: Systematic Review.

 Myiasis is a disease caused by fly larvae that grow in the tissues of animals and humans. It can cause a variety of local symptoms, like erythema or pain, depending on its location, and generalized symptomatology, such as fever and malaise. Myiasis can generate severe complications, for instance sepsis, or directly impact vital tissues.

Estimating Voluntary Activation Of The Elbow And Wrist Muscles In Chronic Hemiparetic Stroke Using Twitch Interpolation Methodology.

One of the cardinal motor deficits that occurs after stroke is paresis, a decrease in the voluntary activation of muscles. Paresis leads to a decrease in voluntary joint strength, impacting stroke survivors' ability to perform activities of daily living (ADLs). Quantifying this decrease in voluntary activation is important when designing rehabilitation interventions to address movement impairments and restore the ability to perform ADLs.

Lower Extremity Motor Impairments in Ambulatory Chronic Hemiparetic Stroke: Evidence for Lower Extremity Weakness and Abnormal Muscle and Joint Torque Coupling Patterns.

Although global movement abnormalities in the lower extremity poststroke have been studied, the expression of specific motor impairments such as weakness and abnormal muscle and joint torque coupling patterns have received less attention. We characterized changes in strength, muscle coactivation and associated joint torque couples in the paretic and nonparetic extremity of 15 participants with chronic poststroke hemiparesis (age 59.6 ± 15.

A Multiple Degree of Freedom Lower Extremity Isometric Device to Simultaneously Quantify Hip, Knee, and Ankle Torques.

Characterization of the joint torque coupling strategies used in the lower extremity to generate maximal and submaximal levels of torque at either the hip, knee, or ankle is lacking. Currently, there are no available isometric devices that quantify all concurrent joint torques in the hip, knee, and ankle of a single leg during maximum voluntary torque generation. Thus, joint-torque coupling strategies in the hip, knee, and concurrent torques at ankle and/or coupling patterns at the hip and knee driven by the ankle have yet to be quantified.

Pilot study to test effectiveness of video game on reaching performance in stroke.

Robotic systems currently used in upper-limb rehabilitation following stroke rely on some form of visual feedback as part of the intervention program. We evaluated the effect of a video game environment (air hockey) on reaching in stroke with various levels of arm support. We used the Arm Coordination Training 3D system to provide variable arm support and to control the hockey stick.

Medical and surgical treatments for obesity have opposite effects on peptide YY and appetite: a prospective study controlled for weight loss.

Context: The effects of medical and surgical treatments for obesity on peptide YY (PYY) levels, in patients with similar weight loss, remain unclear.

Objective: The objective of the study was to assess PYY and appetite before and after Roux-en-Y gastric bypass (RYGB), sleeve gastrectomy (SG), and medical treatment (MED).

Design: This was a prospective, controlled, nonrandomized study.

Association between proinsulin, insulin, proinsulin/insulin ratio, and insulin resistance status with the metabolic syndrome.

The Metabolic Syndrome (MS) constitutes an independent risk factor of cardiovascular disease. There is evidence that proinsulin blood levels and the proinsulin/insulin ratio are associated to the MS. The purpose of this study was to compare proinsulin and insulin, insulin resistance index, and the proinsulin/insulin ratio as predictors of MS.

Muscle focus: a new biomechanical-based index on the selectivity of EMG activity and its application in quantifying the muscle coactivation patterns during isometric torque generation at the elbow and shoulder.

Electromyographic (EMG) recordings are widely used in the study of sensorimotor and neuromuscular systems, more specifically, in the measurement of the muscle activation patterns during isometric torque generation at the elbow and shoulder. In this paper, we introduce a new biomechanics based index of muscle focus. This new index quantifies the degree of selectivity in muscle activation during a shoulder/elbow motor task with a scalar.

Position-dependent torque coupling and associated muscle activation in the hemiparetic upper extremity.

Previous studies have demonstrated abnormal joint torque coupling and associated muscle coactivations of the upper extremity in individuals with unilateral stroke. We investigated the effect of upper limb configuration on the expression of the well-documented patterns of shoulder abduction/elbow flexion and shoulder adduction/elbow extension. Maximal isometric shoulder and elbow torques were measured in stroke subjects in four different arm configurations.

C(-106)T polymorphism of the aldose reductase gene and the progression rate of diabetic retinopathy.

Purpose: To study the C(-106)T polymorphism in the promoter of the aldose reductase (ALR2) gene: (a) its local prevalence and (b) its modulation of the susceptibility for developing retinopathy.

Methods: DNAs of 96 control subjects and 53 long-standing (duration 17.9+/-5.

A biomechanics-based method for the quantification of muscle selectivity in a musculoskeletal system.

In this paper, we have developed a novel and simple method to quantify the ability to selectively activate our muscles in an effective pattern to achieve a particular task. In the context of this study, we define an effective pattern as that in which muscles whose mechanical contribution to the task is greatest, are mostly active, while the antagonist muscles are mostly silent. This new method uses biomechanical parameters to project the multi-channel EMGs into a three-dimensional artificial torque space, where the EMGs are represented as muscle activation vectors.

Modifiability of abnormal isometric elbow and shoulder joint torque coupling after stroke.

Unlike individuals with mild stroke, individuals with severe stroke are constrained to stereotypical movement patterns attributed to abnormal coupling of shoulder abductors with elbow flexors, and shoulder adductors with elbow extensors. Whether abnormal muscle coactivation and associated joint torque patterns can be changed in this population is important to determine given that it bears on the development of effective rehabilitation interventions. Eight subjects participated in a protocol that was designed to reduce abnormal elbow/shoulder joint torque coupling by training them to generate combinations of isometric elbow and shoulder joint torques away from the constraining patterns.

[Mechanisms of hypo and hyper alphalipoproteinemia in Chilean adults].

Background: High density lipoprotein (HDL) cholesterol is inversely associated to atherosclerotic cardiovascular risk. Disturbances in HDL cholesterol plasma levels are frequent in the Chilean population, however the pathophysiological mechanisms are unknown.

Aim: To evaluate the mechanisms involved in the hypo and hyper alfalipoproteinemias in Chilean subjects.

[Risk factors of cardiovascular disease among young adults].

Background: A precise knowledge of the prevalence and importance of cardiovascular risk factors will facilitate the development of preventive strategies.

Aim: To study cardiovascular risk factors among healthy young adults.

Subjects And Methods: Eight hundred and fifty subjects aged 22 to 28 years, living in two cities in Valparaiso province, were studied.

Cardiovascular risk factors in Chilean patients with rheumatoid arthritis.

Objective: Epidemiologic studies have shown an increased mortality rate in patients with rheumatoid arthritis (RA). The most common cause of death in these patients is cardiovascular disease. We estimated the frequency of and examined risk factors for coronary artery disease in Chilean patients with RA.