bluuebunny/crossref_metadata_2025_split huggingface dataset:
Aging‐Related Changes in Motoneuron Autophagy
Authors: Gransee Heather M. , Gonzalez Maria A. , Sieck Gary C. , Mantilla Carlos B. 
Published: November 2023

Autophagy is a series of catabolic processes that involves degradation of cytoplasmic components through lysosomal pathways. There is an important balance that must be met, with impaired autophagy contributing to cell dysfunction and excessive autophagy leading to cell death likely via apoptosis. Indeed autophagy is a dynamic multi‐step process that is modulated positively and negatively at several steps. The role of autophagy in aging‐related motoneuron dysfunction or death is not known. Therefore, it is important to differentiate between the accumulation of autophagosomes due to increased induction of autophagy during conditions of cell stress common across aging‐related conditions, and the accumulation of autophagosomes due to inefficient clearance of damaged organelles and other sequestered cargoes, which reflects impairments in autophagy that would lead to cell dysfunction. We hypothesized that with aging, there is autophagy imbalance causing accumulation of autophagosomes and ultimately neuromuscular dysfunction. Male and female mice at 6 and 24 months of age were used to assess markers of autophagy in the spinal cord. Protein expression of autophagy‐related genes LC3A and LC3B increased in the cervical and lumbar spinal cord of old compared to young mice, whereas protein expression of Atg5, Atg7, and Bcn1 did not change with age. Quantitative real‐time RT‐PCR of microdissected phrenic motoneurons showed an increase in LC3 mRNA expression with age. Overall autophagic flux, which assesses inclusion (or exclusion) of cargo within autophagosomes, delivery of cargo to lysosomes, and subsequent breakdown and release of macromolecules back into the cytosol was evaluated using an mCherry‐GFP‐LC3 sensor. This genetic sensor is designed to monitor LC3 flux through autophagy pathways since the GFP signal is sensitive to the acidic/proteolytic conditions of the lysosome lumen, whereas mCherry fluorescence persists under these environments. We used motoneuron‐like NSC‐34 cells transfected with mCherry‐GFP‐LC3 plasmid to detect changes in the autophagic degradation rate in cells treated with tunicamycin (which leads to cell stress via induction of the unfolded protein response). We observed an increase in yellow vesicles indicating an accumulation of autophagosomes due to inefficient clearance of sequestered cargoes. This genetic sensor indicates impaired autophagy flux in motoneurons in conditions of elevated stress likely present in old age. Taken together, these results suggest impaired autophagy in motoneurons, including phrenic motoneurons, with an associated increase in markers of early autophagosome formation (LC3).Support or Funding InformationSupported by R01‐AG044615.
Effects of C2 Chronic Hemisection on Inspired Volume Generation During High Frequency Spinal Cord Stimulation (HF‐SCS)
Authors: Kowalski Krzysztof E , Dick Thomas E , DiMarco Anthony F , Alilain Warren J 
Published: November 2023

ObjectiveHF‐SCS (300Hz) applied on the ventral epidural surface of the spinal cord results in activation of inspiratory motoneurons via stimulation of spinal cord pathways. The specific pathways by which inspiratory motoneurons are activated by this method however are unknown. The main objective of the present study was to assess the potential role of bulbospinal axons on the activation of phrenic motoneurons during HF‐SCS.MethodsDuring an initial procedure, six rats were hemisected at the C2 spinal level and maintained for 7 days to allow degeneration of the ipsilateral long descending bulbospinal inspiratory axons. HF‐SCS was then applied at the T2 spinal level during spontaneous breathing and following complete C2 spinal section while ipsilateral (EMGipsi), contralateral (EMGcontra) diaphragm EMG, and inspiratory volume were monitored.ResultsAs expected, degeneration of spinal tracts ipsilateral to the hemisection, resulted in minimal EMGipsi, while rhythmic discharge was recorded in the intact, contralateral side (EMGcontra). HF‐SCS however resulted in bilateral rhythmic diaphragm EMG activity. Moreover, the inspired volume achieved during HF‐SCS was similar to that recorded during spontaneous activity (1.44 ± 0.12ml vs. 1.40 ± 0.06ml, respectively). Following complete C2 spinal section, mean inspired volume achieved during HF‐SCS was 1.39 ± 0.08 ml which was not significantly different to that observed before section (NS). In addition, mean maximum inspired volume (3.16 ± 0.15ml) was similar to values previously reported.SummaryIn chronically hemisected rats, following which time cut bulbo‐spinal pathways would have degenerated, the effects of HF‐SCS on inspired volume generation remained unchanged.ConclusionHF‐SCS results in stimulation of pathways located on the ventral surface of the upper thoracic spinal cord, which synapse with sub‐medullary spinal circuits to activate the phrenic motoneuron pools. This technique may be a useful method to support ventilation in ventilator‐dependent tetraplegic patients.Support or Funding InformationSupport: University of Kentucky College of Medicine Funds, MetroHeath Foundation,Disclosure: Dr. DiMarco has a significant financial interest in Synapse BioMedical, Inc, a manufacturer of diaphragm pacing systems.
Respiratory motor deficit in children with spinal cord injury
Authors: Singh Goutam , Trimble Shelley , Aslan Sevda , Behrman Andrea , Ovechkin Alexander 
Published: November 2023

ObjectiveHigh cervical and thoracic injuries leads to paralysis or weakness of muscles of respiration, thereby increases the work load of breathing, which results in low lung volumes and airway pressures. Ineffective cough due to muscle weakness causes difficulty in clearing secretions, which in turn cause mucus retention, pneumonia and other respiratory related complications. Therefore the aim of this study is to compare respiratory functional measures in children with spinal cord injury to children who are neurologically intact (NI) by using a respirator multi‐muscle surface electromyography (sEMG) assessed during standard spirometry and maximal airway pressure efforts. We hypothesized that pulmonary function measures are significantly reduced in children with SCI and associated sEMG activation patterns are significantly different when compared to children who are neurologically intact.Design/Methods14 children with cervical or thoracic SCI were recruited from Frazier rehabilitation Institute and 14 neurologically intact (NI) children were recruited from community. sEMG signals from upper trapezius (UT), pectoralis (PEC), 6intercostal (INT), rectus abdominus (RA), external oblique (OB) thoracic paraspinal (PST) and lumbar paraspinal (PSL) muscles were recorded during maximal inspiratory and expiratory efforts. Outcome measures included Spirometry, sEMG amplitude, PEmax and PImax airway pressures.ResultsChildren with SCI showed significantly lower values of FVC, FEV1, PEmax and PImax compared to NI children. Children with SCI also showed significantly lower activation of rectus abdominis and external oblique muscles during PEmax maneuver. However, no significant difference was observed for muscle activations during PImax maneuver.ConclusionOur study demonstrated the differences in respiratory motor control in children with SCI when compared to NI children. Injury at cervical or high thoracic spinal cord levels resulted in low lung volumes & weakness or paralysis of muscles involved in active expiration & coughing such as rectus abdominus and external oblique thereby leading to compensatory increased activation of accessory muscles, such as upper trapezius and pectoralis. Resultantly, children with SCI exhibited lower values for FVC, PEmax and PImax, compared to NI children.Support or Funding InformationKosair Charities, the Kosair Charities Center for Pediatric NeuroRecovery and The Leona M. and Harry B. Helmsley Charitable Trust.
Spinal Cord Injury Leads to Reductions in Central Nervous System 5HT Coupled with Blunting of Arousal and Genioglossus Muscle Responses to Hypercapnia in Mice
Authors: Komnenov Dragana , Kuhn Donald , Mateika Jason 
Published: November 2023

PurposeThe present investigation was designed to examine if spinal cord injury (SCI) leads to reductions in central nervous system serotonin (5HT). The investigation was also designed to investigate if this reduction was coupled to blunting of arousal responses (AR) and genioglossus muscle sensitivity (GS) to hypercapnia.MethodsTelemetry transmitters were surgically implanted in wild type mice (Tph2+/+) (n = 4) and tryptophan hydroxylase 2 knockout mice (Tph2−/−) (n = 4) to measure electroencephalography, genioglossus muscle activity, core body temperature and gross motor activity. Following recovery, the Tph2+/+ and Tph2−/− mice were placed in whole body plethysmographs and exposed to episodes of 7 % carbon dioxide to determine the AR and GS to hypercapnia during non‐rapid eye movement (NREM) sleep. Following these measures a C2 hemisection of the spinal cord was completed and AR and GS were measured subsequently. In addition, high‐performance liquid chromatography was performed to measure 5HT levels in three brainstem sections (i.e. dorsal respiratory group and hypoglossal nucleus; raphe magnus, obscurus and pallidus; raphe median and paramedian) obtained from 4 intact TPH2+/+ mice and 4 TPH2−/− mice fourteen days after SCI.ResultsTotal 5HT levels in the brainstem were reduced following SCI (3.2 ± 0.1 vs. 1.5 ± 0.3 ng/mg; P < 0.001). In particular, the levels of 5HT in the dorsal respiratory group and hypoglossal nucleus (1.2 ± 0.2 vs. 0.4 ± 0.1 ng/mg; P < 0.01) and in the raphe median and paramedian (1.3 ± 0.2 vs. 0.8 ± 0.1 ng/mg; P < 0.08) were reduced following SCI. In conjunction with the reduction in 5HT the AR (Before SCI: 8.3 ± 4.4 vs. After SCI: 33.8 ± 8.7 s; P < 0.01) and the GS (Before SCI: 180 ± 58 vs. After SCI: 33 ± 10 microvolts; P < 0.02) to hypercapnia was blunted following SCI in the Tph2+/+ but not the Tph2−/− mice.ConclusionsSCI in a spontaneously breathing non‐anesthetized sleeping mouse model was accompanied by a reduction in central nervous system 5HT. This reduction could be responsible for the blunted AR and GS to hypercapnia during NREM sleep. Ultimately, depletion of 5HT could result in an increase in apnea frequency and blunting of the AR and GS could lead to increases in apnea duration following SCI.
Contribution of Expiratory Abdominal Muscle Recruitment in the Perinatal Period Across Sleep Wake Cycles
Authors: Saini Jasmeen , Pagliardini Silvia 
Published: November 2023

Breathing and sleeping are homeostatically regulated processes that are necessary for survival. During sleep, specifically rapid eye movement sleep, breathing is more frequently prone to irregularities in both humans and rodents, especially in preterm and full term newborns. Previous work in our laboratory has demonstrated the occurrence of frequent recruitment of abdominal muscle activity in adult rats during REM sleep, despite REM induced postural muscle atonia. This recruitment was also associated with increased tidal volume and increased respiratory stabilityLittle is known about occurrence of expiratory activity in perinatal rats, specifically across sleep states, and how this recruitment contributes to ventilation. In this study our objective is to investigate the occurrence and the significance of expiratory modulated abdominal muscle recruitment across sleep wake cycles in the postnatal period (postnatal day, P0 to P14) of rats. We hypothesize that in the postnatal period, expiratory muscle activity is also recruited across sleep states and its recruitment contributes to stabilize ventilation, specifically during irregular breathing.We instrumented newborn and juvenile rats with EMG electrodes in neck, intercostal and abdominal muscles and recorded breathing parameters and overt behavior inside a whole body plethysmograph.Our results suggest that neonatal rats experience frequent abdominal muscle recruitment events, which occur in both active and quiet sleep. Our results further indicate that respiratory rate is less variable with onset of abdominal muscle recruitment in active sleep. We conclude that occurrence of expiratory activity is associated with stabilization and potentiation of ventilation during sleep in the postnatal period.Support or Funding InformationNeuroscience and Mental Health Institute, Women and Childrens Health Research Institute, NSERC, CIHR
SEX DIFFERENCES AND PROTEOMIC PROFILING OF DIAPHRAGM WEAKNESS IN CHRONIC HEART FAILURE
Authors: Kelley Rachel C , McDonagh Brian , Hanna Steven , Ferreira Leonardo F 
Published: November 2023

Inspiratory dysfunction occurs in patients with chronic heart failure (CHF). The diaphragm is the primary inspiratory muscle, and diaphragm abnormalities likely contribute to the dyspnea and exercise intolerance that these patients experience. Animal models show that CHF causes diaphragm weakness, but it remains unclear whether disease effects and mechanisms of weakness are sex‐specific. We conducted the current study to test whether CHF effects on diaphragm function and morphology are sex‐specific and to explore putative mechanisms for diaphragm abnormalities via proteomics. We performed myocardial infarction or sham surgery on Sprague Dawley rats. We focused our efforts on animals with severe CHF, determined by 1) transmural infarct ≥ 35% of left ventricle + septal area and 2) right ventricle hypertrophy. We assessed diaphragm isometric contractile function in vitro, fiber type and cross sectional area, and global label free proteomics with mass spectrometry. CHF decreased diaphragm maximal tetanic isometric specific force (N/cm2) by ~20% in both males and females (n = 5–8 per group; P < 0.05). However, the effects on isometric twitch specific force were sex‐specific. CHF decreased twitch specific force (N/cm2) by ~30% (P < 0.05) in males, with no effect in females. There were no effects of disease on fiber type distribution or cross‐sectional area in either sex. Our preliminary proteomic results did not reveal any obvious changes in protein abundance that could explain the decrease in maximal diaphragm force in CHF. For instance, CHF (males) increased the relative quantity of myosin binding protein C fast‐type and troponin T slow isoform and decreased myosin light chain kinase‐2 and phosphorylase b kinase (P < 0.01, false‐discovery rate 1%). In females, our proteomics showed no changes in relative protein quantity with CHF. Overall, our data show that CHF effects on the diaphragm are generally similar between sexes, except for twitch specific force. Our preliminary findings from proteomics suggest that post‐translational modifications, rather than changes in relative quantity, are the main mechanisms underlying diaphragm weakness in CHF.Support or Funding InformationFunding support from NIH R01 HL130318
Seasonal Metabotypes in Small Birds
Authors: Wone Bernard W. M. , Kinchen Jason M. , Swanson David L. 
Published: November 2023

Seasonal changes present challenges to free living birds, such as alterations to food availability and type, as well as metabolic adjustments to cold conditions. To better understand the mechanistic basis of this metabolic flexibility, we conducted a large‐scale metabolic profiling of pectoralis muscle in black‐capped chickadees (BCCH) and American goldfinches (AMGO) during summer and winter seasons. These muscle samples were analyzed using non‐biased, global metabolomics profiling technology based on UHLC/MS/MS2 and GC/MS platforms. A total of 582 metabolites were characterized for summer and winter seasons. Comparison of global biochemical profiles in avian muscle revealed several metabolomic differences. Notably, BCCH showed greater than 2‐fold enrichment in advanced glycation end‐product, ceramides, creatine, branched fatty acid, ketone, and purine and pyrimidine metabolic pathways, whereas AMGO showed greater than 2‐fold enrichment in advanced glycation end‐product, ceramides, disaccharides and oligosaccharides, ascorbate and alderate, glutamate, lysine, and alanine and aspartate metabolic pathways. Declined levels in amino acids might reflect decreasing dietary protein intake and/or protein sparing to conserve muscle for thermogenesis in both bird species during winter. Concomitant decreased abundances in TCA cycle metabolites suggest faster cycling of the oxidative phosphorylation pathway to meet the metabolic demands of thermogenesis during winter. Accordingly, BCCH displayed shifts toward lipid oxidation with seasonal change, whereas AMGO showed declines in ketone bodies suggesting increased energy demands or subtle changes in substrate availability with seasonal change. Interestingly, increased levels of tryptophan metabolites, such as serotonin and tryptophan betaine, were observed for both species during winter season. Collectively, our results provide an unprecedented view into the complex biochemical regulatory events orchestrating seasonal metabolic phenotypes.Support or Funding InformationThis material is based upon work supported by the University of South Dakota start up funds.
Oxygen Consumption of Desert Pupfish at Ecologically‐Relevant Temperatures Suggests a Significant Role for Anaerobic Metabolism
Authors: Hillyard Stanley , van Breukelen Frank 
Published: November 2023

Oxygen consumption is oftentimes used as a proxy for metabolic rate. Routine oxygen consumption (RVO2) of a refuge population of Cyprinodon diabolis acclimated to ecologically relevant temperatures of 28 °C and 33 °C was evaluated at assay temperatures between 25 °C and 38 °C. Different interpretations of the data are available depending on normalization. For instance, RVO2 of smaller fish, measured per fish, was remarkably stable over a wide range of assay temperatures and was not different between acclimation groups. Measured on a mass‐specific basis, RVO2 in larger fish increased more predictably as temperature increased. RVO2 of refuge fish and the closely related pupfish, C. nevadensis mionectes, measured near their respective acclimation temperatures of either 28 °C or 33 °C were essentially identical. However, RVO2 of 28 °C acclimated fish of both species, when measured at 33 °C, was greater than that of the 33 °C acclimated fish measured at 28 °C. We suggest this observed ‘efficiency’ may result from significant anaerobic metabolism use. Experiments investigating metabolic scope (MaxVO2/RVO2) yielded values less than 1 in 33 °C acclimated fish. These values indicate a substantial contribution of anaerobic metabolism to energy utilization by these fish. However, muscle lactate levels are not elevated in exercising fish‐ a result that is consistent with paradoxical anaerobism use.Support or Funding InformationSupported by grants from the US Fish and Wildlife Service and Nevada Department of Wildlife
Effects of altering activity of sensory systems, motor output, skeletal muscle and neurons containing ACH, dopamine, 5‐HT and GABA in Drosophila melanogaster
Authors: Cooper Robin L , Malloy Cole , Majeed Zana R. , Titlow Josh , Mahmood Dlovan D. , Somasundaram Eashwar , Omar Aya , Hermanns Christina , Higgins Jake , Hall Kaylee 
Published: November 2023

The goal of this research is to increase the understanding of how altered neural activity in various modulatory circuits and defined circuits can influence changes in the structure and function of the central and peripheral nervous systems. This is being addressed by the use of, pharmacological agents, optogenetics and thermal control. Some of the genetic approaches involve inserting particular genes which are transgenetically introduced into the genome. Optogenetic regulation allows rapid control of cells to be excited or inhibited. Larvae are reared in varied lighting and thermal control to elicit different motor neuron responses indicative of behavioral changes. Locomotion behavior, response to sensory stimuli and eating responses are being used to measure behavioral assays. The assays will be performed for first, second and third instar larva during the various conditioning paradigms. The degree of synaptic transmission with electrophysiological measures of the synaptic output of the motor neurons is currently being addressed. The hypothesis being tested is that altering defined neural activity during larval development from 1st to 3rd instar will result in structural and functional changes in the synapse; however, they may be able to compensate in novel ways to maintain normal behaviors and physiological control when returned to non‐manipulated conditions. This research is significant because it addresses the possibility of underlying factors sculpting the development of synaptic contacts, as well as factors helping to maintain synaptic contacts after they are established. This research has further implications in the use of optogenetics in driving neural activity, stimulating neurons for regeneration and repair as well as potentially how to offset deconditioning situations, such as zero gravity conditions in aerospace science.Support or Funding InformationKentucky Science and Engineering Foundation (KSEF) at the Kentucky Science and Technology Corporation (RLC), Robert Wood Johnson Foundation (JH) & personal funds (RLC)