The trace amines (TAs), tryptamine, tyramine, and β-phenylethylamine, are synthesized from precursor amino acids via aromatic-L-amino acid decarboxylase (AADC). We explored their role in the ...neuromodulation of neonatal rat spinal cord motor circuits. We first showed that the spinal cord contains the substrates for TA biosynthesis (AADC) and for receptor-mediated actions via trace amine-associated receptors (TAARs) 1 and 4. We next examined the actions of the TAs on motor activity using the in vitro isolated neonatal rat spinal cord. Tyramine and tryptamine most consistently increased motor activity with prominent direct actions on motoneurons. In the presence of N-methyl-D-aspartate, all applied TAs supported expression of a locomotor-like activity (LLA) that was indistinguishable from that ordinarily observed with serotonin, suggesting that the TAs act on common central pattern generating neurons. The TAs also generated distinctive complex rhythms characterized by episodic bouts of LLA. TA actions on locomotor circuits did not require interaction with descending monoaminergic projections since evoked LLA was maintained following block of all Na(+)-dependent monoamine transporters or the vesicular monoamine transporter. Instead, TA (tryptamine and tyramine) actions depended on intracellular uptake via pentamidine-sensitive Na(+)-independent membrane transporters. Requirement for intracellular transport is consistent with the TAs having much slower LLA onset than serotonin and for activation of intracellular TAARs. To test for endogenous actions following biosynthesis, we increased intracellular amino acid levels with cycloheximide. LLA emerged and included distinctive TA-like episodic bouts. In summary, we provided anatomical and functional evidence of the TAs as an intrinsic spinal monoaminergic modulatory system capable of promoting recruitment of locomotor circuits independent of the descending monoamines. These actions support their known sympathomimetic function.
The neonatal rodent spinal cord maintained in vitro is a powerful model system to understand the central properties of spinal circuits generating mammalian locomotion. We describe three enabling ...approaches that incorporate afferent input and attached hindlimbs. (i) Sacral dorsal column stimulation recruits and strengthens ongoing locomotor-like activity, and implementation of a closed positive-feedback paradigm is shown to support its stimulation as an untapped therapeutic site for locomotor modulation. (ii) The spinal cord hindlimbs-restrained preparation allows suction electrode electromyographic recordings from many muscles. Inducible complex motor patterns resemble natural locomotion, and insights into circuit organization are demonstrated during spontaneous motor burst 'deletions', or following sensory stimuli such as tail and paw pinch. (iii) The spinal cord hindlimbs-pendant preparation produces unrestrained hindlimb stepping. It incorporates mechanical limb perturbations, kinematic analyses, ground reaction force monitoring, and the use of treadmills to study spinal circuit operation with movement-related patterns of sensory feedback while providing for stable whole-cell recordings from spinal neurons. Such techniques promise to provide important additional insights into locomotor circuit organization.
Objective: To determine whether minimal snoring is benign in children. Procedure: 22 rarely snoring children (mean age = 6.9 years, 11 females) and age- and sex-matched controls participated in an ...auditory oddball task wearing 128-electrode nets. Parents completed the Conners Parent Rating Scales-Revised Long (CPRS-R:L). Results: Snorers scored significantly higher on four CPRS-R:L subscales. Stepwise regression indicated that two ERP variables from a region of the ERP that peaked at 844 msec post-stimulus onset predicted CPRS-R:L Attention Deficit Hyperactivity Disorder (ADHD) Index scores. Conclusions: Occasional snorers, according to parental report, do exhibit ADHD-like behaviors. Basic sensory processing is longer than in controls, suggesting that delayed frontal activation requires more effort in snorers.
Abstract
This study was aimed to evaluate the yearly incidence of pediatric narcolepsy prior to and following the 2009 H1N1 pandemic and to evaluate seasonal patterns of narcolepsy onset and ...associations with H1N1 influenza infection in the United States. This was a multicenter retrospective study with prospective follow-up. Participants were recruited from members of the Pediatric Working Group of the Sleep Research Network including 22 sites across the United States. The main outcomes were monthly and yearly incident cases of childhood narcolepsy in the United States, and its relationship to historical H1N1 influenza data. A total of 950 participants were included in the analysis; 487 participants were male (51.3%). The mean age at onset of excessive daytime sleepiness (EDS) was 9.6 ± 3.9 years. Significant trend changes in pediatric narcolepsy incidence based on EDS onset (p < .0001) occurred over the 1998–2016 period, peaking in 2010, reflecting a 1.6-fold increase in narcolepsy incidence. In addition, there was significant seasonal variation in narcolepsy incident cases, with increased cases in spring (p < .05). Cross-correlation analysis demonstrated a significant correlation between monthly H1N1 infection and monthly narcolepsy incident cases (p = .397, p < .0001) with a lag time of 8 months. We conclude that there is a significant increase in pediatric narcolepsy incidence after the 2009 H1N1 pandemic in the United States. However, the magnitude of increase is lower than reported in European countries and in China. The temporal correlation between monthly H1N1 infection and monthly narcolepsy incidence, suggests that H1N1 infection may be a contributing factor to the increased pediatric narcolepsy incidence after the 2009 H1N1 pandemics.
Trace amines (TAs), tryptamine, tyramine, octopamine, and β-phenylethylamine, named for their low endogenous concentrations in mammals, are related to the classical monoamine transmitters, but have ...been understudied and thought of as false transmitters. They share structural, physiological, pharmacological, and metabolic similarities with the monoamines, including synthesis by the aromatic-L-amino acid decarboxylase (AADC) enzyme. In 2001, a new class of receptors preferentially activated by the TAs, termed trace amine-associated receptors (TAARs), was discovered establishing a mechanism for TA actions independent of classic monoaminergic mechanisms. While the TAs and some of their receptors are present in the mammalian central nervous system (CNS), their physiologic role remains uncertain. I hypothesized that the TAs are found intrinsically in the spinal cord, and that they are able to modulate spinal neural networks. Using immunohistochemistry, numerous spinal neurons were identified that express AADC, the TAs (octopamine, tryptamine, and tyramine), and TAARs (TAAR1 and TAAR4). Similar results were seen for AADC and TAAR1 with in situ hybridization. The most consistent observation was for labeling D cells associated with the central canal and in motoneurons. Overall, these results provided evidence for the presence of an anatomical substrate onto which the TAs could have intrinsic biological actions in the spinal cord. Using exogenous application of the TAs in the isolated spinal cord in vitro, and in vivo in the mid-thoracic chronically spinalized, I showed that the TAs could induce rhythmic locomotor-like activity. TA injection-induced hindlimb motor rhythms observed in chronic spinalized animals, supports TA spinal actions independent of the descending monoaminergic systems. In the presence of NMDA, TA applications recruited a variety of rhythmic motor patterns in the isolated spinal cord. This ranged from locomotor activity indistinguishable from 5-HT/NMDA induced locomotion to complex patterns including, an episodic form of locomotion where there were locomotor bouts with intervening quiescent periods. TA actions of pattern generating circuits: (i) had slower kinetics of activation than 5-HT and NA, (ii) were attenuated in the presence of monoamine transport inhibitors, and (iii) had increased intracellular labeling even when incubated in a nominally Na+-free solution. Together these results suggest that the TAs required transport into neurons to exert their actions, and that transport occurred by Na+-dependent monoamine transporters as well as additional Na+-independent transporters. Finally, I used the in vitro isolated spinal cord with attached hindlimbs to record electromyographic (EMG) activity from various hindlimb muscles: (i) to compare the relationship between the TAs and serotonin (5-HT) evoked motor coordination, and (ii) to examine the ability of the TAs to modulate ongoing 5-HT and NMDA locomotor-like activity. The TAs produced both the continuous and episodic patterns on muscles as observed in ventral root recordings, but EMG recordings provided more detailed insight into specific muscle actions. The TAs also generally increased both frequency and amplitude of ongoing 5-HT locomotor frequency, with tyramine and octopamine also particularly able to alter 5-HT motor coordination patterns.
To develop and present consensus findings of the National Sleep Foundation sleep timing and variability panel regarding the impact of sleep timing variability on health and performance.
The National ...Sleep Foundation assembled a panel of sleep and circadian experts to evaluate the scientific evidence and conduct a formal consensus and voting procedure. A systematic literature review was conducted using the NIH National Library of Medicine PubMed database, and panelists voted on the appropriateness of 3 questions using a modified Delphi RAND/UCLA Appropriateness Method with 2 rounds of voting.
The literature search and panel review identified 63 full text publications to inform consensus voting. Panelists achieved consensus on each question: (1) is daily regularity in sleep timing important for (a) health or (b) performance? and (2) when sleep is of insufficient duration during the week (or work days), is catch-up sleep on weekends (or non-work days) important for health? Based on the evidence currently available, panelists agreed to an affirmative response to all 3 questions.
Consistency of sleep onset and offset timing is important for health, safety, and performance. Nonetheless, when insufficient sleep is obtained during the week/work days, weekend/non-work day catch-up sleep may be beneficial.
Clinical trials evaluating the safety and effectiveness of sedative medication use in critically ill adults undergoing mechanical ventilation differ considerably in their methodological approach. ...This heterogeneity impedes the ability to compare results across studies. The Sedation Consortium on Endpoints and Procedures for Treatment, Education, and Research Recommendations convened a meeting of multidisciplinary experts to develop recommendations for key methodologic elements of sedation trials in the ICU to help guide academic and industry clinical investigators.
A 2-day in-person meeting was held in Washington, DC, on March 28-29, 2019, followed by a three-round, online modified Delphi consensus process.
Thirty-six participants from academia, industry, and the Food and Drug Administration with expertise in relevant content areas, including two former ICU patients attended the in-person meeting, and the majority completed an online follow-up survey and participated in the modified Delphi process.
The final recommendations were iteratively refined based on the survey results, participants' reactions to those results, summaries written by panel moderators, and a review of the meeting transcripts made from audio recordings. Fifteen recommendations were developed for study design and conduct, subject enrollment, outcomes, and measurement instruments. Consensus recommendations included obtaining input from ICU survivors and/or their families, ensuring adequate training for personnel using validated instruments for assessments of sedation, pain, and delirium in the ICU environment, and the need for methodological standardization.
These recommendations are intended to assist researchers in the design, conduct, selection of endpoints, and reporting of clinical trials involving sedative medications and/or sedation protocols for adult ICU patients who require mechanical ventilation. These recommendations should be viewed as a starting point to improve clinical trials and help reduce methodological heterogeneity in future clinical trials.
Introduction: Acute Chest Syndrome (ACS) is the leading cause of death among children with sickle cell disease (SCD). While the phenotypic variability of ACS is incompletely understood, aberrant ...cell-cell interactions involving the endothelium are central to the pathophysiology. Recent studies suggest that circulating cell-derived extracellular vesicles, termed exosomes, can regulate endothelial integrity. We and others recently demonstrated that exosomes from SCD patients differentially affect endothelial integrity in vitro, but the relationship to specific complications of SCD, such as ACS, are unknown. Given the critical role of the endothelium in ACS, we hypothesized that exosomes from patients with a history of ACS induce increased endothelial damage compared to those without a previous ACS episodes.
Methods: Plasma was isolated from 33 patients with SCD. Patients were >4 weeks since transfusion and had no new health-related complaints. Control plasma samples were from children without SCD or known medical problems, who had a BMI < 95%ile. Exosomes were isolated from plasma using established methodologies. The cellular origin of exosomes was determined using Image Stream flow cytometry. To determine the effects on endothelium, exosomes were added to cultures of human microvascular endothelial cells (HMVEC-D). Intercellular junctions were visualized by immunofluorescent microscopy for VE-cadherin. To quantify effects on endothelial barrier integrity, HMVEC-D endothelial cells were grown to confluence on an Electric Cell-substrate Impedance Sensing (ECIS) array, treated with exosomes and then continuously monitored for 36 hours. Endothelial Nitric Oxide Synthase (eNOS) mRNA expression was assessed in HMVEC-D cells 24 hours post-exposure by qRT-PCR.
Results/Discussion: Flow cytometry demonstrated that the absolute exosome number was greatly increased in patients with SCD compared with controls. In contrast, no significant differences in total exosome numbers emerged between SCD patients based on ACS history. The origin of theexosomes was mainly erythroid (controls:9,661 ± 3,195 /100 uL vs. SCD: 31,338 ± 5,323 /100 uL, p<0.007), but significantly increased numbers of endothelial-, CD34+, lymphocyte-, and monocyte- derived exosomes were also detected. Although a minor population, ACS(+) patients had significantly more monocyte-derived exosomes than ACS(-) patients (monocyte exosomes ACS(-):45.89 ± 22.41 /100 uL vs. ACS(+): 477.4 ± 173.7 /100 uL, p=0.0218); exosomes from other sources did not differ. Immunolocalization of VE-cadherin showed that exosomes from SCD patients (especially ACS(+)) led to the formation of increased gaps between HMVECs as compared to untreated cells or cells treated with exosomes from control patients. ECIS recordings showed that samples from ACS(-) patients differed minimally from control patients, but exosomes from ACS(+)-patients greatly decreased monolayer resistance (relative resistance: ACS(+): 0.981±0.055 vs. ACS(-): 1.124±0.042; p = 0.006). Given its role in pulmonary endothelial dysfunction in ACS, we evaluated the ability of exosomes to induce eNOS expression. ACS(-) samples induced a ~50% increase in eNOS expression when compared to controls (controls;1.01± 0.00 versus ACS(-); 1.61 ± 0.06; p = 0.01) while ACS(+)-derived exosomes failed to induce any significant changes (ACS(+): 0.99 ± 0.05; p < 0.0001 vs. ACS(-)).
Conclusions: The results confirm and expand on our prior observations that circulating exosomes are increased in patients with SCD and contribute to the maintenance of endothelial integrity. Exosomes from ACS(+) patients disrupt the endothelial monolayer in vitro (unlike exosomes from SCD patients who never experienced ACS). We speculate that the increased exosomes contribute to the vascular pathology in all SCD patients. However, some SCD patients are protected by specific exosome cargoes, as in the ACS(-) patients whose exosomes induced eNOS expression by the cultured endothelial cells in vitro, which plays a critical role in endothelial health. Together, the current findings suggest that exosomes are differentially generated based on ACS history, and that their function/cargo (as opposed to their number), modulates endothelial function. Thus, SCD exosomes that induce endothelial dysfunction likely contribute to the pathophysiology of ACS, and may serve as risk-related biomarkers.
No relevant conflicts of interest to declare.
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