bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bacterial metabolism of Ursodeoxycholic Acid is necessary for its protective actions in a mouse model of intestinal inflammation
Authors: Lajczak Natalia Katarzyna , Ward Joseph B , Goggins Bridie J , Keely Simon , Keely Stephen J 
Published: November 2023

BackgroundAlthough inflammatory bowel disease (IBD) represents a significant health and economic burden, current therapies are often ineffective. Altered intestinal epithelial barrier function has been well‐documented to contribute to IBD pathogenesis, with dysregulation of cytokine and antimicrobial protein (AMP) production, along with disrupted mucosal restitution being apparent. Although, the secondary bile acid, ursodeoxycholic acid (UDCA), has been well‐documented to have cytoprotective and anti‐inflammatory actions, its potential for treating IBD has not been well‐investigated.MethodsC57BL/6 mice were given dextran sodium sulphate (DSS, 2.5%) in drinking water for 5 days to induce intestinal inflammation, with severity being recorded as disease activity index (DAI). Mice received Na+‐UDCA, a non‐metabolisable analogue of UDCA, 6‐methyl‐UDCA (6‐MUDCA), or lithocholic acid (LCA) via IP injection each day. Cytokine and HβD release from cultured colonic epithelial cells was analysed by Meso Scale Discovery Assay or ELISA. Wound healing was assessed by scratch assay with wound closure being measured after 48 hrs.ResultsIn DSS‐treated mice, UDCA (30 mg/kg) significantly reduced DAI from 10.0 ± 0.3 in mice treated with DSS alone to 7.2 ± 0.7 in those co‐treated with UDCA (n = 6 – 12, p < 0.001). In cultured monolayers of T84 colonic epithelial cells, UDCA (50 – 150 μM) attenuated epithelial secretion of the proinflammatory AMP, HβD‐2, (n = 3, p < 0.001), while levels of TNF‐α, IL‐8 and Il‐1β were also significantly reduced (n = 4, p < 0.05). In wound healing studies in vitro, UDCA enhanced colonic epithelial migration and restitution, findings which were mirrored in an in vivo model of colonic mucosal healing in endoscopically wounded mice. Finally, further in vivo studies revealed that the metabolically stable UDCA analogue, 6‐MUDCA, was ineffective in preventing inflammation in the DSS model, while LCA (30 mg/kg), the primary bacterial metabolite of UDCA, was protective, reducing DAI to 5.2 ± 0.6 (n=5, p ≤ 0.001).Discussion/ConclusionTogether, our data demonstrate anti‐inflammatory and pro‐healing properties of UDCA in the colon, suggesting a potential role for the bile acid in treatment of IBD. However, in vivo, microbial metabolism to LCA appears to be important for the therapeutic actions of UDCA to be observed.
Thyroid hormone deficiency potentiates GABAergic inhibition of the brainstem respiratory network in newborn rat
Authors: Rousseau Jean‐Philippe , Tenorio Luana , Kinkead Richard 
Published: November 2023

Because thyroid hormones (THs) are present in the brainstem and are essential for both the differentiation of the presynaptic GABAergic neurons and the maturation of the postsynaptic components of the GABAergic system, we proposed that TH deficiency during gestation is sufficient to disrupt GABAergic modulation of the brainstem's respiratory network in newborn rats. Thyroid hormone deficiency in the foetus was recreated by administrating an antithyroid susbstance (Methimazole;MMI) in drinking water of the pregnant dam at concentration of 0,02% (weight per volume; w/v) from the first day of pregnancy (gestational day 1; GD1) to the day of experiment with the newborn. In‐vitro measurements were performed on Sprague Dawley rats aged of 4 days. Fictive breathing (in‐vitro) was measured by extracting the brainstem with a part of the spinal cord and placing it in a chamber where it was superfused with an artificial cerebrospinal fluid (aCSF). The output signal from the respiratory network was recorded by a suction electrode placed on the fourth ventral root representing the inspiratory signal sent to the diaphragm via the phrenic nerve. Compared to controls, pups from MMI treated dams showed 69% decreased phrenic burst frequency under baseline conditions (5.5 ± 0.4 vs 8.0 ± 0.4 bursts/min; treatment effect: P=0.0003). Moreover, they presented an increased dose‐dependent depression of fictive breathing following Muscimol application (GABAA receptor agonist) (dose 0.1μM: −27 ± 7.9 vs −7.8 ± 3.4 % change from baseline; treatment effect: P=0.0233) and increased elevation of phrenic burst frequency following Bicuculline exposure (GABAA receptor antagonist) (dose 8μM: 25.4 ± 5.3 vs 5.3 ± 3.9 % change from baseline; treatment effect P=0.0085). This treatment‐dependent augmentation of GABAergic tone did not affect burst amplitude, thus indicating that the role of TH on GABAergic modulation is selective. We conclude that TH deficiency results in an increased GABAergic inhibition in the core elements of the respiratory control circuit which could explain the reduced phrenic bursts frequency observed in the treated pups. These results provide new hypotheses regarding the origins of respiratory disorders of the newborn involving reduced respiratory drive such as apnea of prematurity.Support or Funding InformationSupported by NSERC.
5HT Depletion Blunts Arousal and Chemoreflex Responses Coupled with Breathing Instability and Cardiac Dysfunction in Mice
Authors: Komnenov Dragana , Pop Alexandru , Kuhn Donald , Mateika Jason 
Published: November 2023

PurposeThe present investigation was designed to examine if genetic depletion of serotonin (5HT) blunts the arousal response (AR) and chemoreflex sensitivity (CS) to hypercapnia and hypoxia leading to an increase in apnea frequency and duration. The study was also designed to determine if these modifications were coupled to coincident modulation of left ventricular (LV) function.MethodsTelemetry transmitters were surgically implanted in wild type mice (Tph2+/+) (n = 12) and tryptophan hydroxylase 2 knockout mice (Tph2−/−) (n = 12) to measure electroencephalography, diaphragmatic muscle activity, core body temperature and gross motor activity. Following recovery, a subset of Tph2+/+ (n = 4) and Tph2−/− (n = 5) mice were placed in whole body plethysmographs and exposed to episodes of 7 % carbon dioxide or 10 % oxygen to determine the AR and CS to hypercapnia and hypoxia during non‐rapid eye movement (NREM) sleep. Cardiac parameters were also measured using echocardiography (n = 4).ResultsThe AR and CS to hypercapnia and hypoxia were blunted in Tph2−/− compared to Tph2+/+ mice (AR hypercapnia − 31.3 ± 5.0 vs. 8.3 ± 4.4 s; hypoxia − 35.0 ± 1.6 vs. 18.6 ± 2.6 s; P < 0.05) (CS hypercapnia − 4.4 ± 0.6 vs. 6.9 ± 0.5; hypoxia − 1.8 ± 0.2 vs. 2.2 ± 0.2 ml/min/% CO2 or O2; P < 0.05). The frequency of apneic events was greater in Tph2−/− compared to Tph2+/+ mice during the light (8.6 ± 1.3 vs. 3.2 ± 1.0 events/hr; P < 0.05) and dark cycle (7.0 ± 1.5 events/hr vs. 1.8 ± 0.6 events/hr; P < 0.05). The duration index of apneic events was greater in Tph2−/− compared to Tph2+/+ mice during the light cycle (3.9 ± 0.3 vs. 2.8 ± 0.2; P < 0.05). The number of apneas terminated by arousal was reduced in the Tph2−/− compared to the Tph2+/+ mice (12.0 ± 1.9 vs.45.6 ± 8.5%; P < 0.05). LV diameter was smaller in Tph2−/− compared to Tph2+/+ mice (1.7 ± 0.1 vs. 2.4 ± 0.2 mm; P < 0.001), consistent with a higher ejection fraction (80.3 ± 1.5 vs. 63.3 ± 3.2 %; P < 0.005) and LV mass (143.4 ± 15.0 vs. 112.6 ± 8.2 mg; P = 0.07).ConclusionsGenetic depletion of 5HT in a spontaneously breathing non‐anesthetized sleeping mouse model results in blunting of the AR and CS to hypercapnia and hypoxia. These blunted responses were coupled to exacerbation of breathing events during NREM sleep. The modifications in LV function indicates that 5HT depletion may be responsible for coincident respiratory and cardiac dysfunction in individuals with central sleep apnea. Our results provide a viable mechanism to explain the increased incidence of coincident respiratory and cardiac dysfunction in individuals with spinal cord injury.
Contribution Of The Pontine Medial Parabrachial Nucleus (mPBN) To The Respiratory Depression From The Benzodiazepine Midazolam (MDZ)
Authors: Zuperku Edward J. , Stucke Astrid G. , Hopp Francis A. , Tomlinson Jack , Krolikowski John G. , Stuth Eckehard A. 
Published: November 2023

The risk of hypoventilation and apnea induced by systemic opioids appears to be greatly increased in the presence of sedatives such as MDZ. A subregion within the mPBN plays a key role in the control of expiratory duration (TE) and in addition, systemic opioid‐induced bradypnea can be reversed by naloxone microinjections in this subregion. We hypothesized that the enhanced depression of breathing may be due an enhanced GABAergic inhibition by MDZ in this subregion. The responses of phrenic nerve activity (PNA) to microinjections of MDZ (100 μM; 360 nl) and the mu‐opioid agonist [D‐Ala2, N‐MePhe4, Gly‐ol]‐enkephalin (DAMGO, 100 μM, 360 nl) into the mPBN subregion were compared in decerebrate, ventilated, vagotomized dogs. Responses to microinjected AMPA were used to identify the tachypneic subregion. Microinjections of MDZ had no effect on inspiratory duration (TI), TE, peak PNA, whereas DAMGO microinjections increased TE (by 85±48%; n=10), slightly increased TI and had no effect on peak PNA. Intravenous administration of MDZ produced a dose‐dependent reduction in TI (−18.5±4.5%) and peak PNA (−29.0±4.1%) with a small non‐significant increase in TE (n=13; peak dose: 238±10 μg/kg). Thus, the respiratory depressant effects of systemic MDZ on breathing do not appear to be mediated by the mPBN subregion where opioids induce bradypnea.Support or Funding InformationSupported by VA grant 2 I01BX000721‐06.
Glutamatergic excitation in the parabrachial nucleus contributes significantly to respiratory rate control in adult rabbits
Authors: Stucke Astrid G , Stuth Eckehard AE , Hopp Francis A , Zuperku Edward J 
Published: November 2023

We have previously identified a subarea of the parabrachial nucleus (PBN) in the adult, in vivo, decerebrate rabbit model where clinical doses of opioids significantly depressed respiratory rate. This study investigated the nature of glutamatergic excitatory drive to this area. The study was approved by the local Animal Care Committee and conformed to NIH standards. Adult New Zealand White rabbits (3–4 kg) were anesthetized, tracheotomized, ventilated, decerebrated and vagotomized. Nerve activity was recorded from the c5 rootlet of the phrenic nerve, time averaged and used to calculate inspiratory and expiratory durations. The PBN was functionally identified by stereotaxic coordinates and a tachypneic response to localized pressure injection of α‐Amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolepropionic acid (AMPA, 50 μM, 70 nl) utilizing a multibarrel glass pipette with a tip diameter of 20μm. The AMPA receptor antagonist 2,3‐ dihydroxy‐6‐nitro‐7‐sulfamoyl‐benzo[f]quinoxaline‐2,3‐dione (NBQX, 1mM, 350nl) and the NMDA receptor antagonist (2R)‐amino‐5‐ phosphonovaleric acid (AP5, 5mM, 350 nl) were injected into the bilateral “tachypneic area”. NBQX depressed respiratory rate by 39±7% (mean±SE, n=16, p<0.001). AP5 depressed respiratory rate by an additional 38±6% (p<0.001). The magnitude of respiratory rate depression was not different when antagonist order was reversed. Local injection of pharmacological concentrations of the clinically used NMDA receptor antagonist ketamine (4mM, 350nl, n=7) depressed respiratory rate by 22±2% (p<0.001). All rate changes were due to significant increases in inspiratory and expiratory duration with each drug (p<0.001). Peak phrenic activity, a measure of tidal volume, was minimally depressed (−8±2%, p<0.001). We conclude that glutamatergic excitation in the PBN that is mediated by AMPA and NMDA receptors contributes significantly to respiratory rate control.Support or Funding InformationSupported by NIH R01GM112960‐01A1 (Dr. Stucke) and VA merit grant I01BX000721 (Dr. Zuperku).
Promoting Respiratory Motor Plasticity After Spinal Cord Injury Through High Frequency Stimulation (HF‐SCS)
Authors: Alilain Warren J , Stoltz Daimen R , Ritter Kyle J , Hager Lydia E , Ghoweri Adam O , Dick Thomas E , DiMarco Anthony F , Kowalski Krzysztof E 
Published: November 2023

More than 50% of the spinal cord injury (SCI) population have injuries at the cervical level. Located at this level are the respiratory bulbospinal pathways which mediate breathing. Therefore, injuries at the cervical level can leave many of these patients unable to breath. One promising intervention to restore breathing is HF‐SCS (300Hz). In previous investigations, we demonstrated that HF‐SCS applied at the T2 level after an experimental complete C2 spinal cord section leads to evoked inspiratory diaphragmatic EMG activity that can enable survival of the animal. However, the extent to which HF‐SCS can promote spinal respiratory motor plasticity in order to promote restoration of breathing function is still unknown. To address this question, we performed a HF‐SCS at the T2 level in six anesthetized rats while recording bilateral diaphragmatic EMG activity one week after C2 hemisection. As expected, C2 hemisection abolished activity in the hemidiaphragm ipsilateral to the hemisection, while spontaneous activity contralateral to the C2 hemisection still remained. HF‐SCS resulted in robust inspiratory activity bilaterally in the diaphragm. Following discontinuation of HF‐SCS bilateral spontaneous activity persisted. Moreover, EMG activity on the hemisected side was synchronized with the contralateral side. Taken together, these results suggest that HF‐SCS after a C2 hemisection can enhance activity and promote plasticity of the crossed phrenic pathways which still remain. Further studies are planned to explore the mechanisms of these observations with the ultimate goal to restore function in patients following SCI.Support or Funding InformationFunded by University of Kentucky College of Medicine Funds & The MetroHeath Foundation.Disclosure: Dr. DiMarco has a significant financial interest in Synapse BioMedical, Inc, a manufacturer of diaphragm pacing systems.
Developmental nicotine exposure increases the response to muscimol in hypoglossal motoneurons.
Authors: Wollman Lila , Levine Richard B , Fregosi Ralph F 
Published: November 2023

Prenatal nicotine exposure with continued exposure through breast milk over the first week of life (developmental nicotine exposure, DNE) is known to cause complex changes to the brainstem respiratory circuit including increased sensitivity to inhibitory neurotransmitters and increased staining of GABAAR‐1a subunit in the hypoglossal nucleus. Here we test the hypothesis that DNE alters the response of hypoglossal motoneurons (XII MNs) to the GABAA receptor agonist Muscimol. We obtainedwhole cell patch clamp recordings from XII MNs in medullary slices (700 micron thick) from DNE pups and control pups. Cells were voltage clamped at −75mV. Using a cesium based intracellular solution, and in the presence of the AMPA receptor antagonists 6‐cyano‐7‐nitroquinoxaline‐2,3‐dione (CNQX), the NMDA receptor antagonist D(‐)‐2‐Amino‐5‐phosphonopentanoic acid (AP‐5), the glycine receptor antagonist Strychnine, and the voltage gated sodium channel blocker Tetrodotoxin, bath application of 0.5 mM Muscimol produces an inward current in these cells. We measured peak inward current from 10 control cells and 10 DNE cells. Our results show that DNE causes in an increased GABAA receptor mediated inward current (Control {n=10} −239.3±30.75 pA, DNE {n=10} −364.4±38.7 pA, P=0.02). This result is consistent with DNE causing increased GABAA receptor expression in XII MNs.Support or Funding InformationNIH RO1H071302 AHA 12GRXIT120S0354
Prenatal Nicotinic Exposure (PNE) Prolongs Superior Laryngeal C‐Fibers (SLCFs)‐mediated Apnea through Upregulating TRPV1 Receptor
Authors: Gao Xiuping , Zhao Lei , Zhuang Jianguo , Xu Fadi 
Published: November 2023

Maternal cigarette smoke is a critical factor in the pathogenesis of sudden infant death syndrome (SIDS). Simulation of SLCFs evokes an immediate apnea and cardiovascular instability, which are potentially life‐threatening and implicated in pathogenesis of SIDS. To date, the impact of PNE on SLCFs has not been explored. We tested hypothesis whether PNE could prolong the SLCF‐mediated apnea, and if so, whether this prolongation is associated with an upregulated expression of TRPV1 on nodose/jugular (N/J) ganglionic neurons retrogradely traced from the superior laryngeal nerve (SLN). To this end, we compared following outcomes between Ctrl and PNE rat pups (postnatal days 11–14): 1) the apneic response to intralaryngeal application of capsaicin (10 μg/kg, 50 μl) to stimulate local TRPV1 in anesthetized preparation; 2) immunoreactivity of TRPV1 in laryngeal sensory neurons of N/J ganglia retrogradely traced by DiI; and 3) TRPV1 currents recorded by whole‐cell patch clamp on cultured sensory laryngeal C‐neurons from N/J ganglia retrogradely traced by DiI. Our results showed that PNE: 1) markedly prolonged the SLCF‐mediated apnea; 2) significantly increased the expression TRPV1 receptors in N/J ganglionic C‐neurons; and 3) augmented the amplitudes of TRPV1 currents on these neurons. The results suggest that PNE is able to prolong the SLCF‐mediated apnea likely though upregulating TRPV1 receptor expression, which may contribute to SIDS.Support or Funding InformationSupported by HL‐107462 and HL‐119683
Lethal Avian Influenza A (H5N1) Virus Induces Ataxic Breathing with Reduced Neurokinin 1 Receptor Expression in the Pre‐Botzinger Complex in Mice
Authors: Zhuang Jianguo , Zang Na , Ye Chunyan , Xu Fadi 
Published: November 2023

The most common symptoms prior to death in patients infected by lethal influenza A (H5N1) are shortness of breath (tachypnea) and respiratory failure. Although the death has been observed in mice at 7 day postinfection, dynamic process of the ventilatory disorders leading to respiratory failure over the infection period and the underlying mechanisms has not been investigated. To this end, the mice were intranasally inoculated with vehicle (Ctrl), 100 PFU HK483 (lethal strain) or HK486 virus (nonlethal strain). We first measured ventilation and arterial blood pH and gases at 0 (before), 2, 4, and 6 days postinfection (dpi). Ctrl and HK486 mice showed no change over the infection period, while HK483 mice presented: 1) gradual body weight loss and hypothermia; 2) a remarkable tachypnea at 2–4 dpi and an ataxic breathing with appearance of long‐lasting apneas at 6 dpi; and 3) hypoxemia and hypercapnemia after 4 dpi that were worse at 6 dpi. Because lethal H5N1 virus is neurotropic and ataxic breathing (hypoxemia) has been reported in rats with an insufficient expression of neural neurokinin 1 receptor (NK1R) in the Pre‐Botzinger complex (PBC), we second asked if HK483 virus replicated in the PBC to induce apoptosis and reduce the population of neurons expressing NK1R. After euthanasia and fixation at 6 dpi, the medullary sections were processed to detect the nucleoprotein of H5N1 virus (NP) alone or coupled with immunoreactivity (IR) of NK1R or CASP3 (a marker for apoptosis). The results showed that HK483 but not HK486 replicated in PBC neurons, particularly local NK1R neurons and reduced the population of PBC NK1R neurons by 75%. CASP3‐IR was detectable in the PBC and NK1R neurons solely in HK483 mice. Our results suggest that lethal H5N1 virus replicates in the PBC to induce apoptosis and thereby reduce population of NK1R neurons, contributing to ataxic breathing and respiratory failure.Support or Funding InformationSupported by HL‐107462 and HL‐119683
Progeria: How much information do we know?
Authors: Glymph Kelly , Agazuma Keshia , Raynes Edilberto , Waller Lauren , Coker Karen , Michaels Natalie , Banting Imelda 
Published: November 2023

Hutchinson‐Gilford Progeria syndrome, also known as Progeria, is a rare genetic disorder, caused by LMNA gene mutation resulting in segmental aging syndrome. It affects one in 20 million people worldwide and has an estimated prevalence of one in four million. It has no sex predilection and affects all races. The syndrome does not manifest signs and symptoms until 9 to 12 months of life and the life expectancy is often only until age 12 to 16 years old (Mayo Clinic, 2016). The purpose of the study was to peruse the available research and to disseminate information to the public in order to increase awareness of the syndrome, and to rectify any misconceptions about the disorder. Using a systematic review of literature, the findings suggested that a multi‐disciplinary approach is needed to help the affected children increase their quality of life.Edilberto A. Raynes, MD, PhD; Kelly Glymph, SPT; Keshia Agazuma, SPT; Lauren Waller, SPT; Karen Coker, PT, DPT, CWS, C/NDT, FACCWS; Natalie Michaels, PT, EdD, GCS Emeritus, and Imelda Banting, PT, MD
NF‐kB, but not HIF‐1a, Inhibition Gene‐specifically Blocks Hypoxia‐induced Microglial Priming
Authors: Ewald Andrea C , Kiernan Elizabeth A , Janke Anna C , Watters Jyoti J 
Published: November 2023

The innate immune system has the capacity for “memory,” the ability to change future cellular responses based on prior experiences. Previous studies in our lab have shown that chronic intermittent hypoxia (IH), a hallmark of sleep‐disordered breathing, can induce cellular memory in both adult and neonatal microglia, CNS resident immune cells. When the immune system is challenged with lipopolysaccharide (LPS) the day following the last IH exposure, LPS‐induced microglial gene expression is augmented, indicating that IH pre‐exposure primes the microglial immune response. Hypoxia‐induced priming of microglial inflammatory gene responses are associated with upregulation of histone 3 lysine 4 trimethylation (H3K4me3) at gene promoters/enhancers, supporting an epigenetic role in microglial memory following hypoxia exposure. To begin to address the signaling mechanisms underlying IH‐induced priming, and the subsequent changes in H3K4me3, we developed an in vitro model of hypoxia which mirrors the microglial responses to IH observed in vivo. Using this model, we tested the hypothesis that hypoxia‐induced potentiation of inflammatory gene expression in microglia requires the activation of the hypoxia‐responsive transcription factors HIF‐1a and NF‐kB, key modulators of inflammatory gene expression. Immortalized N9 microglia were treated overnight with echinomycin (HIF‐1a inhibitor, 1 nM) or BOT‐64 (NF‐kB inhibitor, 3 μM) during the hypoxia exposure period (1.5% O2 for 16 hrs), after which time the cells were washed and stimulated with LPS (100 ng/mL; 3 hrs). We used qRT‐PCR to assess the gene expression of two inflammatory molecules that are potentiated by hypoxia pre‐exposure: inducible nitrogen oxide synthase (iNOS) and interleukin‐1 beta (IL‐1B). We found that while HIF‐1a inhibition did not attenuate the hypoxia‐induced potentiation of iNOS nor IL‐1B, NF‐kB inhibition had gene‐specific effects. Specifically, BOT‐64 blocked the potentiation of iNOS, but not IL‐1B. These results suggest that hypoxia‐induced priming of microglia involves the activation of NF‐kB, as well as at least one other unidentified pathway, to influence microglial gene expression. Ongoing studies are examining if NF‐kB inhibition also attenuates upregulation of H3K4me3 in inflammatory gene regulatory regions to provide insights into the mechanism whereby NF‐kB may regulate hypoxia‐induced microglial priming. Because this form of cellular memory augments the microglial inflammatory response, it may be associated with exacerbated CNS damage during sleep disordered breathing.Support or Funding InformationThis work was supported by NIH R01 NS085226.