scholarly journals Structure and function of the nervous system in nectophores of the siphonophore Nanomia bijuga

2020 ◽  
Author(s):  
Tigran P. Norekian ◽  
Robert W. Meech
Keyword(s):  
Electrical Stimulation ◽  
Nerve Ring ◽  
Synaptic Delay ◽  
Surface Epithelium ◽  
Muscle Fibres ◽  
List Type ◽  
Muscle System ◽  
Neural Input ◽  
Nerve Tracts ◽  
And Function

SummaryAlthough Nanomia nectophores are specialized for locomotion, their cellular elements and complex nerve structures suggest they have multiple subsidiary functions.The main nerve complex is a nerve ring, an adjacent columnar-shaped matrix plus two associated nerve projections. An upper nerve tract appears to provide a sensory input while a lower nerve tract connects with the rest of the colony.The nerve cell cluster that gives rise to the lower nerve tract may relay information from the colony stem.The structure of the extensively innervated “flask cells” located around the bell margin suggests a secretory function. They are ideally placed to release chemical messengers or toxins into the jet of water that leaves the nectophore during each swim.The numerous nematocytes present on exposed nectophore ridges appear to have an entangling rather than a penetrating role.Movements of the velum, produced by contraction of the Claus’ muscle system during backwards swimming, can be elicited by electrical stimulation of the surface epithelium even when the major nerve tracts serving the nerve ring have been destroyed (confirming Mackie, 1964).Epithelial impulses generated by electrical stimulation elicit synaptic potentials in Claus’ muscle fibres. Their amplitude suggests a neural input in the vicinity of the Claus’ muscle system. The synaptic delay is <1.3 ms (Temperature 11.5 to 15° C).During backward swimming radial muscle fibres in the endoderm contract isometrically providing the Claus’ fibres with a firm foundation.Summary StatementNanomia colonies have specialized swimming bells capable of backwards swimming; thrust is redirected by an epithelial signal that leads to muscle contraction via a synaptic rather than an electrotonic event.

scholarly journals Structure and function of the nervous system in nectophores of the siphonophore Nanomia bijuga

2020 ◽  
Vol 223 (24) ◽  
pp. jeb233494
Author(s):  
Tigran P. Norekian ◽  
Robert W. Meech
Keyword(s):  
Action Potentials ◽  
Time Course ◽  
Lower Surface ◽  
Muscle Fibres ◽  
Muscle System ◽  
Slow Potentials ◽  
Nerve Tracts ◽  
System Part ◽  
And Function ◽  
Stimulation Of

ABSTRACTAlthough the bell-shaped nectophores of the siphonophore Nanomia bijuga are clearly specialized for locomotion, their complex neuroanatomy described here testifies to multiple subsidiary functions. These include secretion, by the extensively innervated ‘flask cells' located around the bell margin, and protection, by the numerous nematocytes that line the nectophore's exposed ridges. The main nerve complex consists of a nerve ring at the base of the bell, an adjacent column-shaped matrix plus two associated nerve projections. At the top of the nectophore the upper nerve tract appears to have a sensory role; on the lower surface a second nerve tract provides a motor input connecting the nectophore with the rest of the colony via a cluster of nerve cells at the stem. N. bijuga is capable of both forward and backward jet-propelled swimming. During backwards swimming the water jet is redirected by the contraction of the Claus' muscle system, part of the muscular velum that fringes the bell aperture. Contractions can be elicited by electrical stimulation of the nectophore surface, even when both upper and lower nerve tracts have been destroyed. Epithelial impulses elicited there, generate slow potentials and action potentials in the velum musculature. Slow potentials arise at different sites around the bell margin and give rise to action potentials in contracting Claus’ muscle fibres. A synaptic rather than an electrotonic model more readily accounts for the time course of the slow potentials. During backward swimming, isometrically contracting muscle fibres in the endoderm provide the Claus' fibres with an immobile base.

scholarly journals The Effectiveness Of Quadriceps Strengthening Exercises Combined With Neuromuscular Electrical Stimulation on Patellofemoral Pain Syndrome

2017 ◽  
Vol 5 (2_suppl2) ◽  
pp. 2325967117S0010
Author(s):  
Sezen Karabörklü Argut ◽  
Nilgün Türker ◽  
Derya Çelik ◽  
Önder İsmet Kılıçoğlu
Keyword(s):  
Electrical Stimulation ◽  
Muscle Strength ◽  
Neuromuscular Electrical Stimulation ◽  
Pain Syndrome ◽  
Quadriceps Strength ◽  
Patellofemoral Pain ◽  
Group I ◽  
Strengthening Exercises ◽  
Group Ii ◽  
And Function

Objective: The weakness of the quadriceps strength in patellofemoral pain syndrome (PFPS) is very evident. Therefore, quadriceps strengthening exercises are very important part of the rehabilitation program. Neuromuscular Electrical Stimulation (NMES) is considered one of the methods for increasing quadriceps muscle strength. To evaluate the effectiveness of combined NMES and strengthening exercises to improve the recovery of quadriceps strength and function in patients with PFPS. Methods: This study was planned as a randomized controlled pilot study. A total of 27 patients (mean age=38.9±10.8 years, range=20-60 years; 16 females) with PFPS were assessed and randomly assigned into 2 groups. Group I received a standard program (quadriceps strengthening, hip strengthening and hamstring stretching) and NMES combined with quadriceps strengthening exercises simultaneously. Group II received the same standard program without NMES. Both groups were enrolled 3 times per week for 40 minutes per day in 6 weeks. Patients were assessed at the baseline, 3 rd, 6th, and 12th weeks of treatment. Quadriceps strength was evaluated by isokinetic dynamometer. The range of motion at testing was set between 0 for extension to 90 for flexion. The test was performed at 60 degrees/sn and concentric maximum peak torque value was recorded. Kujala and Lysholm scores were used for functional assessments. The data were analyzed using the SPSS 20.0. Shapiro-Wilk test was used to assess the distribution of data. The changes in dependent variables before treatment, 3 rd, 6th, and 12th weeks were analyzed using a 2 by 4 mixed-model analysis of variance (ANOVA). Pairwise comparisons with paired t test were used to determine whether the Group I or Group II, has changed over time. An intention- to- treat analysis was performed to impute values for missing data. An alpha level of 0.05 was established. Results: The study was completed with 20 patients. Group I (n=10; mean age=39.4±8.5 years; 7 females) and group II (n=10; mean age=43.2±11.7 years; 5 females) had no differences in pre-operative measures (p>.05). There was significant improvements in within groups statistics of all parameters for both groups (p<.05). No differences in quadriceps strength, Kujala and Lysholm scores between groups were found at the different time points (F= 0.86; p = 0.12, F=0,001; p =0.97, F=0.12; p=0.73, respectively) Conclusion: NMES combined with quadriceps strengthening exercises has no additional effect on PFPS patients’ on muscle strength and function. When considering these results, we believe that there is no need to continue the study in progress. [Table: see text]

scholarly journals Respiratory muscle function in the newborn: a narrative review

2021 ◽  
Author(s):  
Theodore Dassios ◽  
Aggeliki Vervenioti ◽  
Gabriel Dimitriou
Keyword(s):  
Congenital Anomalies ◽  
Muscle Function ◽  
Respiratory Muscle ◽  
Work Of Breathing ◽  
Respiratory Muscles ◽  
Current Evidence ◽  
Muscle Fibres ◽  
List Type ◽  
Respiratory Muscle Function ◽  
Neurally Adjusted Ventilator Assist

Abstract Our aim was to summarise the current evidence and methods used to assess respiratory muscle function in the newborn, focusing on current and future potential clinical applications. The respiratory muscles undertake the work of breathing and consist mainly of the diaphragm, which in the newborn is prone to dysfunction due to lower muscle mass, flattened shape and decreased content of fatigue-resistant muscle fibres. Premature infants are prone to diaphragmatic dysfunction due to limited reserves and limited capacity to generate force and avoid fatigue. Methods to assess the respiratory muscles in the newborn include electromyography, maximal respiratory pressures, assessment for thoraco-abdominal asynchrony and composite indices, such as the pressure–time product and the tension time index. Recently, there has been significant interest and a growing body of research in assessing respiratory muscle function using bedside ultrasonography. Neurally adjusted ventilator assist is a novel ventilation mode, where the level of the respiratory support is determined by the diaphragmatic electrical activity. Prolonged mechanical ventilation, hypercapnia and hypoxia, congenital anomalies and systemic or respiratory infection can negatively impact respiratory muscle function in the newborn, while caffeine and synchronised or volume-targeted ventilation have a positive effect on respiratory muscle function compared to conventional, non-triggered or pressure-limited ventilation, respectively. Impact Respiratory muscle function is impaired in prematurely born neonates and infants with congenital anomalies, such as congenital diaphragmatic hernia. Respiratory muscle function is negatively affected by prolonged ventilation and infection and positively affected by caffeine and synchronised compared to non-synchronised ventilation modes. Point-of-care diaphragmatic ultrasound and neurally adjusted ventilator assist are recent diagnostic and therapeutic technological developments with significant clinical applicability.

scholarly journals Task shifting in the care for patients with hand osteoarthritis. Protocol for a randomized controlled non-inferiority trial

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Ingvild Kjeken ◽  
Kjetil Bergsmark ◽  
Ida K. Haugen ◽  
Toril Hennig ◽  
Merete Hermann-Eriksen ◽  
...  
Keyword(s):  
Health Care ◽  
Disease Activity ◽  
Primary Outcome ◽  
Hand Osteoarthritis ◽  
List Type ◽  
Specialist Care ◽  
Randomized Controlled ◽  
Number Of Patients ◽  
Specialist Health Care ◽  
And Function

Abstract Background Current health policy states that patients with osteoarthritis (OA) should mainly be managed in primary health care. Still, research shows that patients with hand OA have poor access to recommended treatment in primary care, and in Norway, they are increasingly referred to rheumatologist consultations in specialist care. In this randomized controlled non-inferiority trial, we will test if a new model, where patients referred to consultation in specialist health care receive their first consultation by an occupational therapy (OT) specialist, is as safe and effective as the traditional model, where they receive their first consultation by a rheumatologist. More specifically, we will answer the following questions: What are the characteristics of patients with hand OA referred to specialist health care with regards to joint affection, disease activity, symptoms and function? Is OT-led hand OA care as effective and safe as rheumatologist-led care with respect to treatment response, disease activity, symptoms, function and patient satisfaction? Is OT-led hand OA care equal to, or more cost effective than rheumatologist-led care? Which factors, regardless of hand OA care, predict improvement 6 and 12 months after baseline? Methods Participants will be patients with hand OA diagnosed by a general practitioner and referred for consultation at one of two Norwegian departments of rheumatology. Those who agree will attend a clinical assessment and report their symptoms and function in validated outcome measures, before they are randomly selected to receive their first consultation by an OT specialist (n = 200) or by a rheumatologist (n = 200). OTs may refer patients to a rheumatologist consultation and vice versa. The primary outcome will be the number of patients classified as OMERACT/OARSI-responders after six months. Secondary outcomes are pain, function and satisfaction with care over the twelve-month trial period. The analysis of the primary outcome will be done by logistic regression. A two-sided 95% confidence interval for the difference in response probability will be formed, and non-inferiority of OT-led care will be claimed if the upper endpoint of this interval does not exceed 15%. Discussion The findings will improve access to evidence-based management of people with hand OA. Trial registration ClinicalTrials.gov, NCT03102788. Registered April 6th, 2017, https://clinicaltrials.gov/ct2/show/NCT03102788?term=Kjeken&draw=2&rank=1 Date and version identifier: December 17th, 2020. First version.

scholarly journals Physical activity in elderly

2015 ◽  
Vol 25 (4) ◽  
pp. 249 ◽  
Author(s):  
Jan Cvecka ◽  
Veronika Tirpakova ◽  
Milan Sedliak ◽  
Helmut Kern ◽  
Winfried Mayr ◽  
...  
Keyword(s):  
Physical Activity ◽  
Electrical Stimulation ◽  
Muscle Mass ◽  
Irreversible Process ◽  
Significant Decline ◽  
Positive Effects ◽  
Age Related ◽  
And Performance ◽  
And Function ◽  
Age Related Changes

Aging is a multifactorial irreversible process associated with significant decline in muscle mass and neuromuscular functions. One of the most efficient methods to counteract age-related changes in muscle mass and function is physical exercise. An alternative effective intervention to improve muscle structure and performance is electrical stimulation. In the present work we present the positive effects of physical activity in elderly and a study where the effects of a 8-week period of functional electrical stimulation and strength training with proprioceptive stimulation in elderly are compared.

scholarly journals Skeletal muscle hypertrophy and structure and function of skeletal muscle fibres in male body builders

2006 ◽  
Vol 570 (3) ◽  
pp. 611-627 ◽  
Author(s):  
Giuseppe D'Antona ◽  
Francesca Lanfranconi ◽  
Maria Antonietta Pellegrino ◽  
Lorenza Brocca ◽  
Raffaella Adami ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Muscle Hypertrophy ◽  
Structure And Function ◽  
Muscle Fibres ◽  
Male Body ◽  
Skeletal Muscle Hypertrophy ◽  
And Function ◽  
Skeletal Muscle Fibres

scholarly journals Distinct effects of different matrix proteoglycans on collagen fibrillogenesis and cell-mediated collagen reorganization

2020 ◽  
Author(s):  
Dongning Chen ◽  
Lucas R. Smith ◽  
Gauri Khandekar ◽  
Pavan Patel ◽  
Christopher K. Yu ◽  
...  
Keyword(s):  
Chondroitin Sulfate ◽  
Core Protein ◽  
Complex Mixture ◽  
List Type ◽  
Collagen Fibrillogenesis ◽  
Fibrous Network ◽  
Large Matrix ◽  
Carbohydrate Components ◽  
And Function

AbstractThe extracellular matrix (ECM) is a complex mixture composed of fibrillar collagens as well as additional protein and carbohydrate components. Proteoglycans (PGs) contribute to the heterogeneity of the ECM and play an important role in its structure and function. While the small leucine rich proteoglycans (SLRPs), including decorin and lumican, have been studied extensively as mediators of collagen fibrillogenesis and organization, the function of large matrix PGs in collagen matrices is less well known. In this study, we showed that different matrix PGs have distinct roles in regulating collagen behaviors. We found that versican, a large chondroitin sulfate PG, promotes collagen fibrillogenesis in a turbidity assay and upregulates cell-mediated collagen compaction and reorganization, whereas aggrecan, a structurally-similar large PG, has different and often opposing effects on collagen. Compared to versican, decorin and lumican also have distinct functions in regulating collagen behaviors. The different ways in which matrix PGs interact with collagen have important implications for understanding the role of the ECM in diseases such as fibrosis and cancer, and suggest that matrix PGs are potential therapeutic targets.HighlightsSmall leucine rich proteoglycans (SLRPs) and large chondroitin sulfate (CS) proteoglycans (PGs) have distinct effects on collagen fibrous network behavior.Unlike other matrix proteoglycans, versican promotes collagen fibrillogenesis in an in vitro spectrophotometric (turbidity) assay.The versican core protein has a larger impact on collagen behavior in a fibrillogenesis assay than its glycosaminoglycan chains do.Versican increases the diameter of collagen fibers and the porosity of collagen fibrous networks, unlike aggrecan and SLRPs.The addition of versican to collagen does not alter fibroblast contractility but leads to enhanced cell-mediated collagen reorganization and contraction.

scholarly journals Electromyogram-Related Neuromuscular Electrical Stimulation for Restoring Wrist and Hand Movement in Poststroke Hemiplegia: A Systematic Review and Meta-Analysis

2019 ◽  
Vol 33 (2) ◽  
pp. 96-111 ◽  
Author(s):  
Katia Monte-Silva ◽  
Daniele Piscitelli ◽  
Nahid Norouzi-Gheidari ◽  
Marc Aureli Pique Batalla ◽  
Philippe Archambault ◽  
...  
Keyword(s):  
Systematic Review ◽  
Clinical Trials ◽  
Electrical Stimulation ◽  
Meta Analysis ◽  
Neuromuscular Electrical Stimulation ◽  
Structure And Function ◽  
Motor Recovery ◽  
Body Structure ◽  
Short Term ◽  
And Function

Background. Clinical trials have demonstrated some benefits of electromyogram-triggered/controlled neuromuscular electrical stimulation (EMG-NMES) on motor recovery of upper limb (UL) function in patients with stroke. However, EMG-NMES use in clinical practice is limited due to a lack of evidence supporting its effectiveness. Objective. To perform a systematic review and meta-analysis to determine the effects of EMG-NMES on stroke UL recovery based on each of the International Classification of Functioning, Disability, and Health (ICF) domains. Methods. Database searches identified clinical trials comparing the effect of EMG-NMES versus no treatment or another treatment on stroke upper extremity motor recovery. A meta-analysis was done for outcomes at each ICF domain (Body Structure and Function, Activity and Participation) at posttest (short-term) and follow-up periods. Subgroup analyses were conducted based on stroke chronicity (acute/subacute, chronic phases). Sensitivity analysis was done by removing studies rated as poor or fair quality (PEDro score <6). Results. Twenty-six studies (782 patients) met the inclusion criteria. Fifty percent of them were considered to be of high quality. The meta-analysis showed that EMG-NMES has a robust short-term effect on improving UL motor impairment in the Body Structure and Function domain. No evidence was found in favor of EMG-NMES for the Activity and Participation domain. EMG-NMES had a stronger effect for each ICF domain in chronic (≥3 months) compared to acute/subacute phases. Conclusion. EMG-NMES is effective in the short term in improving UL impairment in individuals with chronic stroke.

Peripheral neural input to neurons of the middle cervical ganglion in the cat

1984 ◽  
Vol 246 (3) ◽  
pp. R354-R358
Author(s):  
Z. J. Bosnjak ◽  
J. P. Kampine
Keyword(s):  
Electrical Stimulation ◽  
Synaptic Input ◽  
Action Potentials ◽  
Efferent Nerve ◽  
Neural Input ◽  
Central Origin ◽  
Cervical Ganglion ◽  
Intracellular Action ◽  
Peripheral Origin

In vitro studies were conducted on the middle cervical ganglion (MCG) of the cat by recording intracellular action potentials from its neurons. The purpose of this study was to examine the possibility of a peripheral synaptic input to the MCG. Preganglionic electrical stimulation, via the ventral ansa (VA) and dorsal ansa (DA) subclavia, and post-ganglionic electrical stimulation, via the ventrolateral cardiac nerve (VCN), evoked graded synaptic responses that led to the discharge of one or more action potentials in the 14 ganglia studied. The conduction velocity of these pathways ranged from 0.4 to 0.9 m/s. Ten percent of the cells impaled were inexcitable, even with direct intracellular depolarizing current, whereas 80% of the neurons studied received a synaptic input from fibers of both central and peripheral origin. In addition, subthreshold synaptic inputs from peripheral and central origin sum to discharge the cell, suggesting an integration of neural inputs in the MCG. These responses were blocked by d-tubocurarine chloride. This evidence indicates that sympathetic efferent nerve activity can be modified by peripheral excitatory inputs and that these inputs may function as pathways for a peripheral reflex at the level of the MCG.

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