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AMPA receptor (AMPAR) auxiliary subunits are specialized, non-transient binding partners of AMPARs that modulate their ion channel gating properties and pharmacology, as well as their biogenesis and trafficking. The most well characterized families of auxiliary subunits are transmembrane AMPAR regulatory proteins (TARPs) and cornichon homologs (CNIHs) and the more recently discovered GSG1-L. These auxiliary subunits can promote or reduce surface expression of AMPARs in neurons, thereby impacting their functional role in membrane signaling. Here, we show that CNIH-2 enhances the tetramerization of wild type and mutant AMPARs, possibly by increasing the overall stability of the tetrameric complex, an effect that is mainly mediated by interactions with the transmembrane domain of the receptor. We also find CNIH-2 and CNIH-3 show receptor subunit-specific actions in this regard with CNIH-2 enhancing both GluA1 and GluA2 tetramerization whereas CNIH-3 only weakly enhances GluA1 tetramerization. These results are consistent with the proposed role of CNIHs as endoplasmic reticulum cargo transporters for AMPARs. In contrast, TARP γ-2, TARP γ-8, and GSG1-L have no or negligible effect on AMPAR tetramerization. On the other hand, TARP γ-2 can enhance receptor tetramerization but only when directly fused with the receptor at a maximal stoichiometry. Notably, surface expression of functional AMPARs was enhanced by CNIH-2 to a greater extent than TARP γ-2 suggesting that this distinction aids in maturation and membrane expression. These experiments define a functional distinction between CNIHs and other auxiliary subunits in the regulation of AMPAR biogenesis.

The global COVID-19 pandemic has created an urgent demand for large numbers of inexpensive, accurate, rapid, point-of-care diagnostic tests. Analyte-based assays are suitably inexpensive and can be rapidly mass-produced, but for sufficiently accurate performance they require highly optimized antibodies and assay conditions. We used an automated liquid handling system, customized to handle arrays of lateral flow immunoassay (LFA) tests in a high-throughput screen, to identify anti-nucleocapsid antibodies that will perform optimally in an LFA. We tested 1021 anti-nucleocapsid antibody pairs as LFA capture and detection reagents with the goal of highlighting pairs that have the greatest affinity for unique epitopes of the nucleocapsid protein of SARS-CoV-2 within the LFA format. In contrast to traditional antibody screening methods (e.g., ELISA, bio-layer interferometry), the method described here integrates real-time reaction kinetics with transport in, and immobilization directly onto, nitrocellulose. We have identified several candidate antibody pairs that are suitable for further development of an LFA for SARS-CoV-2.

Parvalbumin-expressing (PV) GABAergic interneurons regulate local circuit dynamics. In terms of the excitation driving PV interneuron activity, the N-methyl-d-aspartate receptor (NMDAR)-mediated component onto PV interneurons tends to be smaller than that onto pyramidal neurons but makes a significant contribution to their physiology and development. In the visual cortex, PV interneurons mature during the critical period. We hypothesize that during the critical period, the NMDAR-mediated signaling and functional properties of glutamatergic synapses onto PV interneurons are developmentally regulated. We therefore compared the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR)- and NMDAR-mediated synaptic responses before (postnatal days 15–20, P15–P20), during (P25–P40), and after (P50–P60) the visual critical period. AMPAR miniature excitatory postsynaptic currents (mEPSCs) showed a developmental decrease in frequency, whereas NMDAR mEPSCs were absent or showed extremely low frequencies throughout development. For evoked responses, we consistently saw a NMDAR-mediated component, suggesting pre- or postsynaptic differences between evoked and spontaneous neurotransmission. Evoked responses showed input-specific developmental changes. For intralaminar inputs, the NMDAR-mediated component significantly decreased with development. This resulted in adult intralaminar inputs almost exclusively mediated by AMPARs, suited for the computation of synaptic inputs with precise timing, and likely having NMDAR-independent forms of plasticity. In contrast, interlaminar inputs maintained a stable NMDAR-mediated component throughout development but had a shift in the AMPAR paired-pulse ratio from depression to facilitation. Adult interlaminar inputs with facilitating AMPAR responses and a substantial NMDAR component would favor temporal integration of synaptic responses and could be modulated by NMDAR-dependent forms of plasticity. NEW & NOTEWORTHY We show for the first time input-specific developmental changes in the N-methyl-d-aspartate receptor component and short-term plasticity of the excitatory drive onto layers 2/3 parvalbumin-expressing (PV) interneurons in the visual cortex during the critical period. These developmental changes would lead to functionally distinct adult intralaminar and interlaminar glutamatergic inputs that would engage PV interneuron-mediated inhibition differently.

GABA(A) receptors (GABA(A)R) are inhibitory ion channels ubiquitously expressed in the central nervous system and play critical roles in brain development and function. Benzodiazepines are positive allosteric modulators of GABA(A)R, by enhancing channel opening frequency when GABA is bound to the receptor. Midazolam is a commonly used benzodiazepine. It is frequently used for premature infants, but the long-term consequences of its use in this patient population are not well established. Here we studied the acute effects of midazolam on immature synapses. Using a rodent organotypic hippocampal slice preparation, we evaluated how midazolam affects inhibitory synaptic transmission onto CA1 pyramidal neurons. We find that 1 μM midazolam enhances evoked inhibitory post synaptic currents (eIPSCs) at a holding potential of −60 mV. Similarly, 1 μM midazolam enhances miniature IPSCs (mIPSCs) in CA1 pyramidal neurons at holding potentials of −60 mV and −30 mV. At depolarized holding potentials, however, midazolam no longer enhances mIPSCs. Depolarization of the postsynaptic cell by itself increases mIPSC decay, which apparently occludes the allosteric effects of midazolam. These results provide insight into how a benzodiazepine and membrane voltage may modulate GABA(A)R function in developing circuits.

Background The purpose of this study was to determine the impact of a formal surgical research program (leading to a postgraduate degree) during residency, on future research productivity. Methods We surveyed all North American graduates of the McGill University general surgery residency program between 1987 and 2005. The survey included questions on research involvement before, during, and after general surgery residency. This was combined with a literature search revealing all research publications of the participants. Outcomes were the yearly average of publications and awarded funding as faculty members. Results Seventy-five of 119 graduates (63%) responded. Staff physicians who had participated in formal research programs during residency (n = 35), compared with those who had not (n = 40), produced more publications per year (2.8 ± 2.3 vs 1.1 ± 1.2, P Conclusions Residents who had participated in formal research programs during residency were more likely to have greater academic success.

Patients with esophageal atresia/tracheoesophageal fistula (EA-TEF) can develop Barrett esophagus as a long-term consequence of their condition. Intestinal metaplasia (IM), a risk factor for developing adenocarcinoma of the esophagus, has not been well characterized in the pediatric population.Retrospective review of patients with EA-TEF followed at 3 academic pediatric centers between the years 1997 and 2014.Among 542 children and adolescents, 1.3% (7 patients, 5 girls) were diagnosed with IM based on endoscopy and pathology. Six of the patients had EA-TEF type C, whereas the last patient had a "long gap" type A atresia. Patients were diagnosed with gastric metaplasia either before the IM diagnosis in 4 patients or concomitantly in 3. The median (range) age of diagnosis for gastric metaplasia was 7.9 (range 2-17.2) and for IM 10.9 (2-17.2) years. Gastroesophageal reflux (GER) symptoms were nonspecific. Five patients were on proton pump inhibitor therapy for symptomatic GER at the time of diagnosis of IM. 2 of the 7 patients had previously undergone Nissen fundoplication. One patient, who had undergone a Nissen fundoplication, was restarted on proton pump inhibitor once the diagnosis of IM was made. All patients had repeated endoscopy and dysplasia was not observed with a median follow-up of 1.7 (range 1-4.9) years.IM occurs in patients with EA-TEF, some as young as 2 years. Therefore, early endoscopic surveillance should be considered in this GER-prone population.

Background Controversy persists about the need to admit patients after successful reduction of intussusception. Our hypothesis is that pediatric intussusception can be managed with discharge from the emergency department (ED) after reduction without increasing morbidity, yielding significant cost savings. Methods A chart review over 10years was performed at two Canadian institutions. Data abstracted included: demographics, length of stay (LOS), initial and recurrence management. Primary outcome was early recurrence and resultant management, including LOS and need for operative intervention. Costs were calculated using hospital-specific data. Results 584 patient records were assessed: 329 patients were managed with admission after reduction, 239 as outpatients. In the admission group, 28 patients had at least one recurrence (8.5%), with 8 after discharge. In the outpatient group, 21 patients had at least one recurrence (8.8%), with 19 after discharge. The difference post-discharge was significant (p=0.004). Outcomes of recurrence did not differ, with 2 patients in each group requiring operative intervention. Average LOS in the admission group was 90h, with additional average cost of $1771 per non-operated patient. Conclusions Pediatric intussusception can be safely managed as an outpatient with reliable follow up. Discharge from the ED reduces hospital charges without increasing morbidity. This approach should be considered in managing patients with intussusception.

Beta amyloid (Abeta), a peptide generated from the amyloid precursor protein (APP) by neurons, is widely believed to underlie the pathophysiology of Alzheimer's disease. Recent studies indicate that this peptide can drive loss of surface AMPA and NMDA type glutamate receptors. We now show that Abeta employs signaling pathways of long-term depression (LTD) to drive endocytosis of synaptic AMPA receptors. Synaptic removal of AMPA receptors is necessary and sufficient to produce loss of dendritic spines and synaptic NMDA responses. Our studies indicate the central role played by AMPA receptor trafficking in Abeta-induced modification of synaptic structure and function.

A large body of evidence has implicated Abeta peptides and other derivatives of the amyloid precursor protein (APP) as central to the pathogenesis of Alzheimer's disease (AD). However, the functional relationship of APP and its proteolytic derivatives to neuronal electrophysiology is not known. Here, we show that neuronal activity modulates the formation and secretion of Abeta peptides in hippocampal slice neurons that overexpress APP. In turn, Abeta selectively depresses excitatory synaptic transmission onto neurons that overexpress APP, as well as nearby neurons that do not. This depression depends on NMDA-R activity and can be reversed by blockade of neuronal activity. Synaptic depression from excessive Abeta could contribute to cognitive decline during early AD. In addition, we propose that activity-dependent modulation of endogenous Abeta production may normally participate in a negative feedback that could keep neuronal hyperactivity in check. Disruption of this feedback system could contribute to disease progression in AD.

Some centers advocate using antibiotics before enema reduction to prevent septic complications. Our objective was to determine whether using antibiotics before reduction provided any improvement in outcomes.With institutional review board approval, patients from 2 centers were compared: 1 where antibiotics were administered, and one where they were not. This retrospective cohort study from January 2005 to December 2010 evaluated demographic data, episodes of postreduction fever, hospital stay, and analgesia requirements.One hundred eighteen patients were identified: 83 males (70.3%) and 35 females (29.7%). The median age was 24 months (range, 1-180). Fifty-six patients (57.7%) received antibiotics, whereas 41 (42.7%) did not. Twenty-one patients (17.8%) had missing data and were excluded. The incidence of fever postreduction was not statistically different between groups: 12.8% for those who received antibiotics vs 17.9% for those who did not (P = .7367). No adverse antibiotic reactions were reported. Average time to oral feeds was 7.3 vs 10.6 hours (P = .06), and the length of stay was 1.7 vs 1.4 days (P = .07).Although antibiotics are administered routinely in some centers, they appear of little value. Financial costs and potential adverse reactions must be considered. Further prospective evaluation is being conducted using a larger sample size to confirm these results.

There is a keen interest in identifying the effects of Aβ on synapses. Here we review some of the published work on its effects on excitatory synaptic transmission and plasticity. We also provide new information indicating that activity-induced release of Aβ from either pre- or postsynaptic neurons can block structural plasticity.

The regulated trafficking of GluR1 contributes significantly to synaptic plasticity, but studies addressing the function of the GluR1 C-terminal PDZ-ligand domain in this process have produced conflicting results. Here, we resolve this conflict by showing that apparently similar C-terminal mutations of the GluR1 PDZ-ligand domain result in opposite physiological phenotypes during activity- and CamKII-induced synaptic plasticity.