scholarly journals Diaphragm muscle activity across respiratory motor behaviors in awake and lightly anesthetized rats

2018 ◽  
Vol 124 (4) ◽  
pp. 915-922 ◽  
Author(s):  
Federico Jimenez-Ruiz ◽  
Obaid U. Khurram ◽  
Wen-Zhi Zhan ◽  
Heather M. Gransee ◽  
Gary C. Sieck ◽  
...  
Keyword(s):  
Fixed Effects ◽  
Random Effect ◽  
Respiratory Muscles ◽  
Mixed Linear Model ◽  
Male Rats ◽  
Diaphragm Muscle ◽  
Emg Activity ◽  
Airway Patency ◽  
Motor Behaviors ◽  
Generating Capacity

Respiratory muscles such as the diaphragm are active across a range of behaviors including ventilation and higher-force behaviors necessary for maintenance of airway patency, and minimal information is available regarding anesthetic effects on the capacity of respiratory muscles to generate higher forces. The purpose of the present study was to determine whether diaphragm EMG activity during lower-force behaviors, such as eupnea and hypoxia-hypercapnia, is differentially affected compared with higher-force behaviors, such as a sigh, in lightly anesthetized animals. In adult male rats, chronically implanted diaphragm EMG electrodes were used to measure the effects of low-dose ketamine (30 mg/kg) and xylazine (3 mg/kg) on root mean square (RMS) EMG amplitude across a range of motor behaviors. A mixed linear model was used to evaluate the effects of ketamine-xylazine anesthesia on peak RMS EMG and ventilatory parameters, with condition (awake vs. anesthetized), behavior (eupnea, hypoxia-hypercapnia, sigh), side (left or right hemidiaphragm), and their interactions as fixed effects and animal as a random effect. Compared with the awake recordings, there was an overall reduction of peak diaphragm RMS EMG across behaviors during anesthesia, but this reduction was more pronounced during spontaneous sighs (which require ~60% of maximal diaphragm force). Respiratory rates and duty cycle during eupnea and hypoxia-hypercapnia were higher in awake compared with anesthetized conditions. These results highlight the importance of identifying anesthetic effects on a range of respiratory motor behaviors, including sighs necessary for maintaining airway patency. NEW & NOTEWORTHY Respiratory muscles accomplish a range of motor behaviors, with forces generated for ventilatory behaviors comprising only a small fraction of their maximal force generating capacity. Induction of anesthesia exerts more robust effects on the higher-force diaphragm motor behaviors such as sighs compared with eupnea. This novel information on effects of low, sedative doses of a commonly used anesthetic combination (ketamine-xylazine) highlights the importance of identifying anesthetic effects on a range of respiratory motor behaviors.

scholarly journals Chronic assessment of diaphragm muscle EMG activity across motor behaviors

2011 ◽  
Vol 177 (2) ◽  
pp. 176-182 ◽  
Author(s):  
Carlos B. Mantilla ◽  
Yasin B. Seven ◽  
Juan N. Hurtado-Palomino ◽  
Wen-Zhi Zhan ◽  
Gary C. Sieck
Keyword(s):  
Diaphragm Muscle ◽  
Emg Activity ◽  
Motor Behaviors

scholarly journals Key aspects of phrenic motoneuron and diaphragm muscle development during the perinatal period

2008 ◽  
Vol 104 (6) ◽  
pp. 1818-1827 ◽  
Author(s):  
Carlos B. Mantilla ◽  
Gary C. Sieck
Keyword(s):  
Muscle Development ◽  
Respiratory Muscles ◽  
Motor Units ◽  
Perinatal Period ◽  
Diaphragm Muscle ◽  
Postnatal Maturation ◽  
Motor Behaviors ◽  
Phrenic Motoneurons ◽  
Phrenic Motoneuron ◽  
Key Aspects

At the time of birth, respiratory muscles must be activated to sustain ventilation. The perinatal development of respiratory motor units (comprising an individual motoneuron and the muscle fibers it innervates) shows remarkable features that enable mammals to transition from in utero conditions to the air environment in which the remainder of their life will occur. In addition, significant postnatal maturation is necessary to provide for the range of motor behaviors necessary during breathing, swallowing, and speech. As the main inspiratory muscle, the diaphragm muscle (and the phrenic motoneurons that innervate it) plays a key role in accomplishing these behaviors. Considerable diversity exists across diaphragm motor units, but the determinant factors for this diversity are unknown. In recent years, the mechanisms underlying the development of respiratory motor units have received great attention, and this knowledge may provide the opportunity to design appropriate interventions for the treatment of respiratory disease not only in the perinatal period but likely also in the adult.

scholarly journals Diaphragm electromyographic activity following unilateral midcervical contusion injury in rats

2017 ◽  
Vol 117 (2) ◽  
pp. 545-555 ◽  
Author(s):  
Sabhya Rana ◽  
Gary C. Sieck ◽  
Carlos B. Mantilla
Keyword(s):  
Motor Units ◽  
Diaphragm Muscle ◽  
Emg Activity ◽  
High Threshold ◽  
Perineuronal Net ◽  
Neural Drive ◽  
Motor Behaviors ◽  
Neuromotor Control ◽  
Phrenic Motoneurons ◽  
Contusion Injury

Contusion-type injuries to the spinal cord are characterized by tissue loss and disruption of spinal pathways. Midcervical spinal cord injuries impair the function of respiratory muscles and may contribute to significant respiratory complications. This study systematically assessed the impact of a 100-kDy unilateral C4 contusion injury on diaphragm muscle activity across a range of motor behaviors in rats. Chronic diaphragm electromyography (EMG) was recorded before injury and at 1 and 7 days postinjury (DPI). Histological analyses assessed the extent of perineuronal net formation, white-matter sparing, and phrenic motoneuron loss. At 7 DPI, ∼45% of phrenic motoneurons were lost ipsilaterally. Relative diaphragm root mean square (RMS) EMG activity increased bilaterally across a range of motor behaviors by 7 DPI. The increase in diaphragm RMS EMG activity was associated with an increase in neural drive (RMS value at 75 ms after the onset of diaphragm activity) and was more pronounced during higher force, nonventilatory motor behaviors. Animals in the contusion group displayed a transient decrease in respiratory rate and an increase in burst duration at 1 DPI. By 7 days, following midcervical contusion, there was significant perineuronal net formation and white-matter loss that spanned 1 mm around the injury epicenter. Taken together, these findings are consistent with increased recruitment of remaining motor units, including more fatigable, high-threshold motor units, during higher force, nonventilatory behaviors. Changes in diaphragm EMG activity following midcervical contusion injury reflect complex adaptations in neuromotor control that may increase the risk of motor-unit fatigue and compromise the ability to sustain higher force diaphragm efforts. NEW & NOTEWORTHY The present study shows that unilateral contusion injury at C4 results in substantial loss of phrenic motoneurons but increased diaphragm muscle activity across a range of ventilatory and higher force, nonventilatory behaviors. Measures of neural drive indicate increased descending input to phrenic motoneurons that was more pronounced during higher force, nonventilatory behaviors. These findings reveal novel, complex adaptations in neuromotor control following injury, suggestive of increased recruitment of more fatigable, high-threshold motor units.

scholarly journals Frequency‐domain analysis of diaphragm muscle EMG activity across ventilatory and non‐ventilatory motor behaviors

2011 ◽  
Vol 25 (S1) ◽  
Author(s):  
Yasin Baris Seven ◽  
Carlos B. Mantilla ◽  
Wen‐Zhi Zhan ◽  
Gary C. Sieck
Keyword(s):  
Frequency Domain ◽  
Domain Analysis ◽  
Frequency Domain Analysis ◽  
Diaphragm Muscle ◽  
Emg Activity ◽  
Motor Behaviors

scholarly journals Recruitment of rat diaphragm motor units across motor behaviors with different levels of diaphragm activation

2014 ◽  
Vol 117 (11) ◽  
pp. 1308-1316 ◽  
Author(s):  
Yasin B. Seven ◽  
Carlos B. Mantilla ◽  
Gary C. Sieck
Keyword(s):  
Motor Unit ◽  
Motor Neurons ◽  
Motor Units ◽  
Motor Unit Recruitment ◽  
Diaphragm Muscle ◽  
Emg Activity ◽  
Motor Behaviors ◽  
Airway Occlusion ◽  
Recruitment Order ◽  
Central Drive

Phrenic motor neurons are recruited across a range of motor behaviors to generate varying levels of diaphragm muscle (DIAm) force. We hypothesized that DIAm motor units are recruited in a fixed order across a range of motor behaviors of varying force levels, consistent with the Henneman Size Principle. Single motor unit action potentials and compound DIAm EMG activities were recorded in anesthetized, neurally intact rats across different motor behaviors, i.e., eupnea, hypoxia-hypercapnia (10% O2 and 5% CO2), deep breaths, sustained airway occlusion, and sneezing. Central drive [estimated by root-mean-squared (RMS) EMG value 75 ms after the onset of EMG activity (RMS75)], recruitment delay, and onset discharge frequencies were similar during eupnea and hypoxia-hypercapnia. Compared with eupnea, central drive increased (∼25%) during deep breaths, and motor units were recruited ∼12 ms earlier ( P < 0.01). During airway occlusion, central drive was ∼3 times greater, motor units were recruited ∼30 ms earlier ( P < 0.01), and motor unit onset discharge frequencies were significantly higher ( P < 0.01). Recruitment order of motor unit pairs observed during eupnea was maintained for 98%, 87%, and 84% of the same pairs recorded during hypoxia-hypercapnia, deep breaths, and airway occlusion, respectively. Reversals in motor unit recruitment order were observed primarily if motor unit pairs were recruited <20 ms apart. These results are consistent with DIAm motor unit recruitment order being determined primarily by the intrinsic size-dependent electrophysiological properties of phrenic motor neurons.

scholarly journals BDNF effects on functional recovery across motor behaviors after cervical spinal cord injury

2017 ◽  
Vol 117 (2) ◽  
pp. 537-544 ◽  
Author(s):  
Vivian Hernandez-Torres ◽  
Heather M. Gransee ◽  
Carlos B. Mantilla ◽  
Yao Wang ◽  
Wen-Zhi Zhan ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Motor Neurons ◽  
Neurotrophic Factor ◽  
Cervical Spinal Cord ◽  
Brain Derived Neurotrophic Factor ◽  
Diaphragm Muscle ◽  
Emg Activity ◽  
Motor Behaviors ◽  
Airway Occlusion ◽  
Spinal Cord Hemisection

Unilateral C2 cervical spinal cord hemisection (SH) disrupts descending excitatory drive to phrenic motor neurons, thereby paralyzing the ipsilateral diaphragm muscle (DIAm) during ventilatory behaviors. Recovery of rhythmic DIAm activity ipsilateral to injury occurs over time, consistent with neuroplasticity and strengthening of spared synaptic inputs to phrenic motor neurons. Localized intrathecal delivery of brain-derived neurotrophic factor (BDNF) to phrenic motor neurons after SH enhances recovery of eupneic DIAm activity. However, the impact of SH and BDNF treatment on the full range of DIAm motor behaviors has not been fully characterized. We hypothesized that all DIAm motor behaviors are affected by SH and that intrathecal BDNF enhances the recovery of both ventilatory and higher force, nonventilatory motor behaviors. An intrathecal catheter was placed in adult, male Sprague-Dawley rats at C4 to chronically infuse artificial cerebrospinal fluid (aCSF) or BDNF. DIAm electromyography (EMG) electrodes were implanted bilaterally to record activity across motor behaviors, i.e., eupnea, hypoxia-hypercapnia (10% O2 and 5% CO2), sighs, airway occlusion, and sneezing. After SH, ipsilateral DIAm EMG activity was evident in only 43% of aCSF-treated rats during eupnea, and activity was restored in all rats after BDNF treatment. The amplitude of DIAm EMG (root mean square, RMS) was reduced following SH during eupnea and hypoxia-hypercapnia in aCSF-treated rats, and BDNF treatment promoted recovery in both conditions. The amplitude of DIAm RMS EMG during sighs, airway occlusion, and sneezing was not affected by SH or BDNF treatment. We conclude that the effects of SH and BDNF treatment on DIAm activity depend on motor behavior. NEW & NOTEWORTHY This study demonstrates that after unilateral C2 spinal cord hemisection (SH), there are differences in the spontaneous recovery of diaphragm (DIAm) electromyographic activity during ventilatory compared with more forceful, nonventilatory motor behaviors. Furthermore, we show that intrathecal delivery of brain-derived neurotrophic factor (BDNF) at the level of the phrenic motor neuron pool enhances recovery of ipsilateral DIAm activity following SH, exerting main effects on recovery of ventilatory but not higher force, nonventilatory behaviors.

scholarly journals A random effects population dynamics model based on proportions-at-age and removal data for estimating total mortality

2012 ◽  
Vol 69 (11) ◽  
pp. 1881-1893 ◽  
Author(s):  
Verena M. Trenkel ◽  
Mark V. Bravington ◽  
Pascal Lorance
Keyword(s):  
Population Dynamics ◽  
Random Effects ◽  
Fixed Effects ◽  
Random Effect ◽  
Total Mortality ◽  
Estimation Bias ◽  
Effective Sample Size ◽  
Dynamics Model ◽  
Population Dynamics Model ◽  
Study Parameter

Catch curves are widely used to estimate total mortality for exploited marine populations. The usual population dynamics model assumes constant recruitment across years and constant total mortality. We extend this to include annual recruitment and annual total mortality. Recruitment is treated as an uncorrelated random effect, while total mortality is modelled by a random walk. Data requirements are minimal as only proportions-at-age and total catches are needed. We obtain the effective sample size for aggregated proportion-at-age data based on fitting Dirichlet-multinomial distributions to the raw sampling data. Parameter estimation is carried out by approximate likelihood. We use simulations to study parameter estimability and estimation bias of four model versions, including models treating mortality as fixed effects and misspecified models. All model versions were, in general, estimable, though for certain parameter values or replicate runs they were not. Relative estimation bias of final year total mortalities and depletion rates were lower for the proposed random effects model compared with the fixed effects version for total mortality. The model is demonstrated for the case of blue ling (Molva dypterygia) to the west of the British Isles for the period 1988 to 2011.

Determining the Rate of Ergot-alkaloid Degradation in Toxic Endophyte-infected Tall Fescue Hay and Haylage During Long Term Storage

2021 ◽  
Vol 99 (Supplement_2) ◽  
pp. 22-22
Author(s):  
Charles A Zumbaugh ◽  
Susannah A Gonia ◽  
Kathryn M Payne ◽  
Thomas B Wilson
Keyword(s):  
Tall Fescue ◽  
Ergot Alkaloid ◽  
Fixed Effects ◽  
High Performance ◽  
Nutritive Value ◽  
Day Treatment ◽  
Random Effect ◽  
Storage Period ◽  
Neutral Detergent Fiber ◽  
Experimental Unit

Abstract The objectives of this experiment were to determine changes in the nutritive value and ergot alkaloid concentrations of endophyte-infected tall fescue hay and haylage during a 180-d storage period. Forage from a single field of Kentucky-31 tall fescue was cut for hay in late June and allowed to dry in the field. The dry matter (DM) of the windrow of cut forage was measured every 2 h after clipping. Forage was sampled from the windrow in 6 location blocks once forage DM reached target levels for haylage and hay treatments. Haylage and hay samples were taken when the DM of the windrow reached 50% and 80%, respectively. Seven subsamples of each treatment within block were chopped to 1.91 cm in length with a lettuce chopper and vacuum sealed in oxygen-excluding bags. Sample bags were stored indoors and opened at 30 d intervals over the 180-d storage period. Samples were analyzed for pH, nutritive value, and individual ergot alkaloid concentrations using high-performance liquid chromatography. Within each storage day, treatment within block was considered the experimental unit. Data were analyzed in SAS using the MIXED procedure with fixed effects of treatment, day, and the treatment by day interaction. Location block was considered a random effect. As expected, pH was decreased for haylage compared to hay at all time points (P &lt; 0.01) and DM was greater (P &lt; 0.01) for hay compared to haylage. Neutral detergent fiber values were greater (P &lt; 0.01) for hay compared to haylage and declined during storage (P &lt; 0.01). Total ergot alkaloid concentrations did not differ by treatment (P = 0.61), but ergovaline concentrations declined (P &lt; 0.01) during storage. Collectively, these results indicate minimal differences in nutritive value and ergot alkaloid concentrations between hay and haylage during storage, and that ergovaline concentrations decline during storage.

scholarly journals Effect of hay type on cecal and fecal microbiome and fermentation parameters in horses

2020 ◽  
Author(s):  
Rachel J Sorensen ◽  
James S Drouillard ◽  
Teresa L Douthit ◽  
Qinghong Ran ◽  
Douglas G Marthaler ◽  
...  
Keyword(s):  
Fixed Effects ◽  
Volatile Fatty Acids ◽  
Random Effect ◽  
Alpha Diversity ◽  
Sampling Location ◽  
Rrna Gene ◽  
Illumina Hiseq ◽  
Fecal Microbiome ◽  
Β Diversity ◽  
Fermentation Parameters

Abstract The effect of hay type on the microbiome of the equine gastrointestinal tract is relatively unexplored. Our objective was to characterize the cecal and fecal microbiome of mature horses consuming alfalfa or Smooth Bromegrass (brome) hay. Six cecally cannulated horses were used in a split plot design run as a crossover in 2 periods. Whole plot treatment was ad libitum access to brome or alfalfa hay fed over two 21-d acclimation periods with subplots of sampling location (cecum and rectum) and sampling hour. Each acclimation period was followed by a 24-h collection period where cecal and fecal samples were collected every 3 h for analysis of pH and volatile fatty acids (VFA). Fecal and cecal samples were pooled and sent to a commercial lab (MR DNA, Shallowater, TX) for amplification of the V4 region of the 16S rRNA gene and sequenced using Illumina HiSeq. Main effects of hay on VFA, pH, and taxonomic abundances were analyzed using the MIXED procedure of SAS 9.4 with fixed effects of hay, hour, location, period, all possible interactions and random effect of horse. Alpha and β diversity were analyzed using the R Dame package. Horses fed alfalfa had greater fecal than cecal pH (P ≤ 0.05) whereas horses fed brome had greater cecal than fecal pH (P ≤ 0.05). Regardless of hay type, total volatile fatty acid (VFA) concentrations were greater (P ≤ 0.05) in the cecum than in feces, and alfalfa resulted in greater (P ≤ 0.05) VFA concentrations than brome in both sampling locations. Alpha diversity was greater (P ≤ 0.05) in fecal compared to cecal samples. Microbial community structure within each sampling location and hay type differed from one another (P ≤ 0.05). Bacteroidetes were greater (P ≤ 0.05) in the cecum compared to the rectum, regardless of hay type. Firmicutes and Firmicutes:Bacteroidetes were greater (P ≤ 0.05) in the feces compared to cecal samples of alfalfa-fed horses. In all, fermentation parameters and bacterial abundances were impacted by hay type and sampling location in the hindgut.

Corporate Ownership Structure and Its Effect on Capital Structure: Evidence from BSE Listed Manufacturing Companies in India

2021 ◽  
pp. 227797522096830
Author(s):  
Palaniappan Gurusamy
Keyword(s):  
Capital Structure ◽  
Ownership Structure ◽  
Fixed Effects ◽  
Random Effect ◽  
Corporate Ownership ◽  
Manufacturing Companies ◽  
Hausman Test ◽  
Lm Test ◽  
Corporate Ownership Structure ◽  
The Capital Structure

The study aims to examine the relationship between corporate ownership structure and capital structure of BSE listed manufacturing firms in India. The study has included the sample of 357 companies which covers 16 major sectors during the period of 2006–2015. Considering the dynamic panel nature of the data relating to the capital structure and the ownership structure variables. The analysis undertakes a novel approach of examining the determinants both single equation and reduced equation models. In order to determine the most appropriate model, based on the F test, the Breusch Pagan LM test and finally the Hausman Test is conducted. The Hausman test result has been estimated by the fixed effect model is better than the other two models such as pooled OLS and random effect estimation. Based on the fixed effects results, size, risk and profitability have a highly significant relationship with leverage. Meanwhile, the growth opportunities and tangibility represent insignificant values. The study found that the explanatory variables of the promoters’ ownership and the institutional ownership have a negative impact on leverage, while the corporate ownership has a positive influence on the capital structure decision. The individual or public ownership has a negative and significantly related to the capital structure, whereas the effect of the foreign ownership inversely related to the firm’s leverage.

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