Dynamic Changes in Chromatin Accessibility Occur in CD8+ T Cells Responding to Viral Infection.

In response to acute infection, naive CD8+ T cells expand, differentiate into effector cells, and then contract to a long-lived pool of memory cells after pathogen clearance. During chronic infections or in tumors, CD8+ T cells acquire an "exhausted" phenotype. Here we present genome-wide comparisons of chromatin accessibility and gene expression from endogenous CD8+ T cells responding to acute and chronic viral infection using ATAC-seq and RNA-seq techniques. Acquisition of effector, memory, or exhausted phenotypes was associated with stable changes in chromatin accessibility away from the naive T cell state. Regions differentially accessible between functional subsets in vivo were enriched for binding sites of transcription factors known to regulate these subsets, including E2A, BATF, IRF4, T-bet, and TCF1. Exhaustion-specific accessible regions were enriched for consensus binding sites for NFAT and Nr4a family members, indicating that chronic stimulation confers a unique accessibility profile on exhausted cells.

Break Wave Lithotripsy for Urolithiasis: Results of the First-in-Human International Multi-Institutional Clinical Trial.

PURPOSE: This study reports on a prospective, multicenter, single-arm, clinical trial utilizing the SonoMotion (San Mateo, California) Break Wave lithotripsy (BWL) device to fragment urinary stones. MATERIALS AND METHODS: Patients with a urinary stone underwent a single treatment of 30 minutes and peak negative pressure of 4.5 to 8 MPa. Subjects were contacted and outcomes assessed at 7, 14, and 35 days after treatment, with clinical follow-up and CT imaging 70 ± 14 days postprocedure. The primary objectives were to assess the safety (hematomas, complications, etc) and effectiveness of BWL (any fragmentation, residual fragments ≤4 mm or ≤2 mm, and completely stone-free rate) as assessed via noncontrast CT-kidneys, ureters, and bladder. RESULTS: Forty-four patients with a ureteral (43%) or renal (57%) stone were treated across 5 centers. Stone fragmentation occurred in 88% of cases; 70% had fragments ≤ 4 and 51% ≤ 2 mm, while 49% were completely stone free on CT; no serious adverse events were reported. Eighty-six percent of patients received either no analgesic medication at all (50%) or minor analgesia (36%). After determining optimal therapy settings, 36 patients were treated and the effectiveness improved exhibiting fragmentation in 92% (33/36), residual fragments ≤ 4 mm in 75% and 58% with fragments ≤ 2 mm with 58% completely stone free. Effectiveness was less in subjects with lower pole stones with 81% fragmentation, 71% having fragments ≤ 4 mm, 29% with fragments ≤ 2 mm, and 29% completely stone free; of distal ureteral stone patients, 89% were completely stone free. CONCLUSIONS: BWL offered safe and effective noninvasive stone therapy requiring little to no anesthesia and was carried out successfully in nonoperative environments. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT03811171.

Retrospective first-in-human use of the LithoVue™ Elite ureteroscope to measure intrarenal pressure.

OBJECTIVE: To report on our first-in-human experience using the LithoVue Elite™ ureteroscope (Boston Scientific Corp., Marlborough, MA, USA) to measure intrarenal pressure (IRP) during flexible ureteroscopy. PATIENTS AND METHODS: A single-arm retrospective observational analysis was performed in 50 consecutive patients undergoing ureteroscopic lithotripsy using the LithoVue Elite™ system with pressure sensing capability between April 2022 and February 2023 at two centres. A pressure bag set at 150 mmHg or hand irrigation with a 60-mL syringe was used for irrigation and a ureteric access sheath (UAS) was placed at the physician's discretion. Median and maximum IRPs, and relative cumulative time exceeding 20, 40, 60, 80, 100, 120, 140, 160, and 200 mmHg per total procedure time were analysed. The two-sample Mann-Whitney U-test was used, with statistical significance set at P < 0.05. RESULTS: The median (interquartile range [IQR]) patient age and body mass index (BMI) was 62.5 (46.7-68.2) years and 27.6 (23.3-32.1) kg/m2 , respectively. During the median (IQR) total procedure time of 31.9 (17.4-44.9) min, the median and maximum IRPs were 28.5 (20.0-47.5) and 174.0 (133.5-266.0) mmHg, respectively. IRP remained at <60 mmHg during 92% of the procedure times. Patients with Asian ethnicity, and those without pre-stenting or UAS use exhibited longer cumulative/total durations exceeding pre-defined IRP cut-off values. The smaller 10/12-F UAS did not lower pressures as much as the 11/13-F or 12/14-F UAS (P < 0.001). Age, diabetes, hypertension, preoperative α-blockade, stone size, and BMI did not show any statistically significant associations with IRP. CONCLUSIONS: The IRP can now be routinely measured during ureteroscopy. Patients had a median IRP of 28.5 mmHg and a maximum of 174 mmHg. Using a smaller UAS (10/12 F), Asian ethnicity, and tight ureters were found to have higher IRPs.

Preoperative patient optimization for endourological procedures: the current best clinical practice.

PURPOSE OF REVIEW: Despite technological advancements in endourological surgery, there is room for improvement in preoperative patient optimization strategies. This review updates recent best clinical practices that can be implemented for optimal surgical outcomes. RECENT FINDINGS: Outcome and complication predictions using novel scoring systems and techniques have shown to assist clinical decision-making and patient counseling. Innovative preoperative simulation and localization methods for percutaneous nephrolithotomy have been evaluated to minimize puncture-associated adverse events. Novel antibiotic prophylaxis strategies and further recognition of risk factors that attribute to postoperative infections have shown the potential to minimize perioperative morbidity. Accumulating data on the roles of preoperative stenting and selective oral alpha-blockers adds evidence to the current paradigm of preventive measures for ureteral injury. SUMMARY: Ample tools and technologies exist that can be utilized preoperatively to improve surgical outcomes. The combination of these innovations, along with validation in larger-scale studies, presents the cornerstone of future urolithiasis management.

Cardiovascular toxicities with pediatric tyrosine kinase inhibitor therapy: An analysis of adverse events reported to the Food and Drug Administration.

We sought to examine cardiovascular toxicities associated with tyrosine kinase inhibitors in pediatrics. We examined 1624 pediatric adverse events with imatinib, dasatinib, sorafenib, pazopanib, crizotinib, and ruxolitinib reported to the Food and Drug Administration between January 1, 2015, and August 14, 2020. There were 102 cardiovascular event reports. Hypertension was the most commonly reported cardiovascular event and was most frequently associated with sorafenib and pazopanib. The presence of infection increased the reporting odds of cardiovascular events overall and specifically cardiac arrest, heart failure, and hypertension. These data provide early insight into cardiovascular toxicities with tyrosine kinase inhibitor use in pediatrics.

An anchor-tether 'hindered' HCN1 inhibitor is antihyperalgesic in a rat spared nerve injury neuropathic pain model.

BACKGROUND: Neuropathic pain impairs quality of life, is widely prevalent, and incurs significant costs. Current pharmacological therapies have poor/no efficacy and significant adverse effects; safe and effective alternatives are needed. Hyperpolarisation-activated cyclic nucleotide-regulated (HCN) channels are causally implicated in some forms of peripherally mediated neuropathic pain. Whilst 2,6-substituted phenols, such as 2,6-di-tert-butylphenol (26DTB-P), selectively inhibit HCN1 gating and are antihyperalgesic, the development of therapeutically tolerable, HCN-selective antihyperalgesics based on their inverse agonist activity requires that such drugs spare the cardiac isoforms and do not cross the blood-brain barrier. METHODS: In silico molecular dynamics simulation, in vitro electrophysiology, and in vivo rat spared nerve injury methods were used to test whether 'hindered' variants of 26DTB-P (wherein a hydrophilic 'anchor' is attached in the para-position of 26DTB-P via an acyl chain 'tether') had the desired properties. RESULTS: Molecular dynamics simulation showed that membrane penetration of hindered 26DTB-Ps is controlled by a tethered diol anchor without elimination of head group rotational freedom. In vitro and in vivo analysis showed that BP4L-18:1:1, a variant wherein a diol anchor is attached to 26DTB-P via an 18-carbon tether, is an HCN1 inverse agonist and an orally available antihyperalgesic. With a CNS multiparameter optimisation score of 2.25, a >100-fold lower drug load in the brain vs blood, and an absence of adverse cardiovascular or CNS effects, BP4L-18:1:1 was shown to be poorly CNS penetrant and cardiac sparing. CONCLUSIONS: These findings provide a proof-of-concept demonstration that anchor-tethered drugs are a new chemotype for treatment of disorders involving membrane targets.

TNF stimulation primarily modulates transcriptional burst size of NF-κB-regulated genes.

Cell-to-cell heterogeneity is a feature of the tumor necrosis factor (TNF)-stimulated inflammatory response mediated by the transcription factor NF-κB, motivating an exploration of the underlying sources of this noise. Here, we combined single-transcript measurements with computational models to study transcriptional noise at six NF-κB-regulated inflammatory genes. In the basal state, NF-κB-target genes displayed an inverse correlation between mean and noise characteristic of transcriptional bursting. By analyzing transcript distributions with a bursting model, we found that TNF primarily activated transcription by increasing burst size while maintaining burst frequency for gene promoters with relatively high basal histone 3 acetylation (AcH3) that marks open chromatin environments. For promoters with lower basal AcH3 or when AcH3 was decreased with a small molecule drug, the contribution of burst frequency to TNF activation increased. Finally, we used a mathematical model to show that TNF positive feedback amplified gene expression noise resulting from burst size-mediated transcription, leading to a subset of cells with high TNF protein expression. Our results reveal potential sources of noise underlying intercellular heterogeneity in the TNF-mediated inflammatory response.

Predictors of rapidly progressive interstitial lung disease and mortality in patients with autoantibodies against melanoma differentiation-associated protein 5 dermatomyositis.

OBJECTIVE: Anti-melanoma differentiation-associated protein 5 (MDA5)-positive DM is associated with rapidly progressive interstitial lung disease (RP-ILD) and high mortality. This multicentre retrospective study aimed to identify predictors of mortality and RP-ILD. METHODS: Anti-MDA5-positive DM patients were identified from the Hong Kong Myositis Registry and the Clinical Data Analysis and Reporting System. Clinical characteristics were reviewed. Risk factors for mortality and RP-ILD were identified. RESULTS: Among the 116 recruited patients, 100 (86.2%) had ILD, 47 (40.5%) had RP-ILD and 44 (37.9%) patients died. Cox regression analysis revealed RP-ILD [hazard ratio (HR) 9.735 (95% CI 3.905, 24.272)], age >52 years [HR 4.750 (95% CI 1.692, 13.333)], ferritin level >2800 pmol/l [HR 3.042 (95% CI 1.323, 6.997)] and lactate dehydrogenase (LDH) >400 IU/l [HR 2.290 (95% CI 1.009, 5.198)] were independent predictors of mortality. With regard to RP-ILD, analyses showed that potential predictors at baseline included age >50 years [HR 2.640 (95% CI 1.277, 5.455)], LDH >300 IU/l [HR 3.189 (95% CI 1.469, 6.918)], fever [HR 1.903 (95% CI 0.956, 3.790)] and neutrophil:lymphocyte ratio >7.0 [HR 1.967 (95% CI 0.942, 4.107)]. We proposed a prediction model based on fever, LDH, age and white cell count (FLAW) to stratify the risk of development of RP-ILD. The probability of RP-ILD in a patient with a score of 4 was 100%. A small internal validation cohort showed the odds of RP-ILD with FLAW scores of 0, 1, 2 and 3 were 0%, 0%, 42.9% and 75%, respectively. CONCLUSIONS: Anti-MDA5-associated RP-ILD is significantly associated with poor survival rates. The FLAW model maybe useful to predict the development of RP-ILD.

Prospective randomized trial of 2 versus 12-weeks of postoperative antibiotics after percutaneous nephrolithotomy in complex patients with infection-related kidney stones.

PURPOSE: Treatment of struvite kidney stones requires complete surgical stone removal combined with antibiotic therapy to eliminate urinary tract infections and preventive measures to reduce stone recurrence. The optimal duration of antibiotic therapy is unknown. We sought to determine if 2- or 12-weeks of antibiotics post percutaneous nephrolithotomy (PNL) for infection stones resulted in better outcomes for stone recurrence and positive urine cultures. MATERIAL AND METHODS: This multi-center, prospective randomized trial evaluated patients with the clinical diagnosis of infection stones. Patients were randomized to 2- or 12-weeks of postoperative oral antibiotics (nitrofurantoin or culture-specific antibiotic) and included if residual fragments were ≤4 mm on computed tomography imaging after PNL. Imaging and urine analyses were performed at 3-, 6-, and 12-months post-procedure. RESULTS: Thirty-eight patients were enrolled and randomized to either 2-weeks (n = 20) or 12-weeks (n = 18) of antibiotic therapy post-PNL. Eleven patients were excluded due to residual fragments >4 mm, and 3 patients were lost to follow-up. The primary outcome was the stone-free rate (SFR) at 6 months post-PNL. At 3-, 6-, and 12-months follow-up, SFRs were 72.7% versus 80.0%, 70.0% versus 57.1%, 80.0% versus 57.1% (p = ns), between 2- and 12-week-groups, respectively. At 3-, 6-, and 12-months follow-up, positive urine cultures were 50.0% versus 37.5%, 50.0% versus 83.3%, and 37.5% versus 100% between 2- and 12-week groups, respectively (p = ns). CONCLUSIONS: For patients with stone removal following PNL, neither 2-weeks nor 12-weeks of postoperative oral antibiotics is superior to prevent stones and recurrent positive urine cultures.

Myositis-specific autoantibodies and their clinical associations in idiopathic inflammatory myopathies.

BACKGROUND: Myositis-specific autoantibodies (MSAs) have been found to be present predominantly in patients with idiopathic inflammatory myopathies (IIMs). This study aimed to investigate the prevalence of MSAs and their associated complications in a cohort of patients with IIMs. METHODS: This was a multicentered prospective study. Consecutive adult Chinese patients with IIMs in the regional hospitals in Hong Kong were followed up from July 2016 to January 2018. Clinical characteristics, treatment history, and disease complications were documented. A commercially available immunoblot assay was used to detect the MSAs. RESULTS: Out of the 201 patients studied, at least one MSA was found in 63.2% of patients. The most common among the identified MSAs were the anti-melanoma differentiation-associated gene 5 antibody (anti-MDA5 Ab) and the anti-transcriptional intermediary factor 1-gamma antibody (anti-TIF1-γ Ab) (both 13.9%), followed by anti-Jo-1 antibody (12.4%). Anti-MDA5 was present exclusively in dermatomyositis (DM) and was strongly associated with digital ulcers, amyopathy, and rapidly progressive interstitial lung disease (RP-ILD). Anti-TIF1γ was strongly associated with refractory rash and malignancy. Independent risk factors of RP-ILD included anti-MDA5 (OR 14.5), clinically amyopathic DM (OR 13.9), and history of pulmonary tuberculosis (OR 12.2). Cox regression analysis showed that anti-TIF1γ (HR 3.55), DM (HR 3.82), and family history of cancer (HR 3.40) were independent predictors of malignancy. CONCLUSIONS: MSA testing enables dividing of patients with IIMs into phenotypically homogeneous subgroups and prediction of potentially life-threatening complications.

The Application of Next-generation Sequencing Tumor Molecular Profiling in the Diagnosis and Management of a Case of Acute Myelogenous Leukemia With MLL-PTD in a Pediatric Heart Transplant Recipient.

A 6-year-old girl with a history of heart transplantation was diagnosed with myelodysplastic syndrome, which progressed to acute myelogenous leukemia. Comprehensive genomic profiling of her tumor discovered an MLL-PTD (partial tandem duplication) and she received chemotherapy and a hematopoietic stem cell transplant (HSCT). She subsequently relapsed and tumor molecular profiling was repeated, revealing 2 new potentially targetable mutations (FLT3 and IDH2). A novel treatment regimen targeting these mutations with sorafenib and azacitidine without using cytotoxic chemotherapy produced remission and she subsequently pursued a second HSCT. She remains disease-free 17 months after HSCT. This case report demonstrates how repeated tumor molecular profiling provided novel actionable information for the diagnosis and management at 2 timepoints.

Diagnostic and Treatment Challenges for Acquired Hemophilia A in Pediatrics: Report of 2 Cases.

Acquired hemophilia A (AHA) occurs rarely in children. We report 2 cases of adolescent females with AHA. The first case underwent bone marrow aspiration/biopsy during workup, which was complicated by bleeding. Bleeding resolved after initiation of therapy with cyclophosphamide and glucocorticoid, but despite the addition of rituximab, she did not achieve complete remission until treatment with intravenous immunoglobulin. In the second case, we observed that a mixing study without incubation will not detect an acquired factor VIII inhibitor, but further workup based on suspicion for AHA led to the correct diagnosis. Both had significant medication toxicity which required treatment modification.

TRIM25 promotes Capicua degradation independently of ERK in the absence of ATXN1L.

BACKGROUND: Aberrations in Capicua (CIC) have recently been implicated as a negative prognostic factor in a multitude of cancer types through the derepression of targets downstream of the mitogen-activated protein kinase (MAPK) signaling cascade, such as oncogenic E26 transformation-specific (ETS) transcription factors. The Ataxin-family protein ATXN1L has previously been reported to interact with CIC in both developmental and disease contexts to facilitate the repression of CIC target genes and promote the post-translational stability of CIC. However, little is known about the mechanisms at the base of ATXN1L-mediated CIC post-translational stability. RESULTS: Functional in vitro studies utilizing ATXN1LKO human cell lines revealed that loss of ATXN1L leads to the accumulation of polyubiquitinated CIC protein, promoting its degradation through the proteasome. Although transcriptomic signatures of ATXN1LKO cell lines indicated upregulation of the mitogen-activated protein kinase pathway, ERK activity was found to contribute to CIC function but not stability. Degradation of CIC protein following loss of ATXN1L was instead observed to be mediated by the E3 ubiquitin ligase TRIM25 which was further validated using glioma-derived cell lines and the TCGA breast carcinoma and liver hepatocellular carcinoma cohorts. CONCLUSIONS: The post-translational regulation of CIC through ATXN1L and TRIM25 independent of ERK activity suggests that the regulation of CIC stability and function is more intricate than previously appreciated and involves several independent pathways. As CIC status has become a prognostic factor in several cancer types, further knowledge into the mechanisms which govern CIC stability and function may prove useful for future therapeutic approaches.

Pediatric Acute Lymphoblastic Leukemia, Version 2.2020, NCCN Clinical Practice Guidelines in Oncology.

Acute lymphoblastic leukemia (ALL) is the most common pediatric malignancy. Advancements in technology that enhance our understanding of the biology of the disease, risk-adapted therapy, and enhanced supportive care have contributed to improved survival rates. However, additional clinical management is needed to improve outcomes for patients classified as high risk at presentation (eg, T-ALL, infant ALL) and who experience relapse. The NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) for pediatric ALL provide recommendations on the workup, diagnostic evaluation, and treatment of the disease, including guidance on supportive care, hematopoietic stem cell transplantation, and pharmacogenomics. This portion of the NCCN Guidelines focuses on the frontline and relapsed/refractory management of pediatric ALL.

Ureteral stents: the good the bad and the ugly.

PURPOSE OF REVIEW: Ureteral stents are necessary in the routine practice of an urologist. Choosing the correct stent and being aware of the options available will allow urologists to provide the best possible care for patients and value to the healthcare system. This review seeks to educate urologists regarding improvements in stent technology currently available or in development. RECENT FINDINGS: Research from around the world is underway to discover an ideal stent - one that is comfortable for patients, resists infection and encrustation and is affordable for hospital systems. Stent design alterations and stent coatings are revealing reductions in encrustation and bacterial colonization. Biodegradable stents and magnetic stents are being tested to prevent the discomfort of cystoscopic removal. Intraureteral stents are proving efficacious while eliminating an irritating coil from the bladder and the symptoms associated with it. SUMMARY: The studies highlighted in this review provide encouraging results in the pursuit of the ideal stent while opening discussion around new concepts and further areas of research.

Acute Pancreatitis Associated With Cytarabine During the Treatment of Pediatric Acute Myeloid Leukemia.

Pancreatitis is a common complication of many pediatric oncology drugs - most commonly asparaginase, followed by pentamidine, mercaptopurine, corticosteroids, and trimethoprim-sulfamethoxazole. Cytarabine-associated pancreatitis is not often mentioned in the pediatric oncology literature. We report the case of a 10-year-old female with acute myeloid leukemia who developed cytarabine-associated pancreatitis.

Exhaustion-associated regulatory regions in CD8+ tumor-infiltrating T cells.

T-cell exhaustion is a progressive loss of effector function and memory potential due to persistent antigen exposure, which occurs in chronic viral infections and cancer. Here we investigate the relation between gene expression and chromatin accessibility in CD8+ tumor-infiltrating lymphocytes (TILs) that recognize a model tumor antigen and have features of both activation and functional exhaustion. By filtering out accessible regions observed in bystander, nonexhausted TILs and in acutely restimulated CD8+ T cells, we define a pattern of chromatin accessibility specific for T-cell exhaustion, characterized by enrichment for consensus binding motifs for Nr4a and NFAT transcription factors. Anti-PD-L1 treatment of tumor-bearing mice results in cessation of tumor growth and partial rescue of cytokine production by the dysfunctional TILs, with only limited changes in gene expression and chromatin accessibility. Our studies provide a valuable resource for the molecular understanding of T-cell exhaustion in cancer and other inflammatory settings.

Fold-Change Detection of NF-κB at Target Genes with Different Transcript Outputs.

The transcription factor nuclear factor (NF)-κB promotes inflammatory and stress-responsive gene transcription across a range of cell types in response to the cytokine tumor necrosis factor (TNF). Although NF-κB signaling exhibits significant variability across single cells, some target genes supporting high levels of TNF-inducible transcription exhibit fold-change detection of NF-κB, which may buffer against stochastic variation in signaling molecules. It is unknown whether fold-change detection is maintained at NF-κB target genes with low levels of TNF-inducible transcription, for which stochastic promoter events may be more pronounced. Here, we used a microfluidic cell-trapping device to measure how TNF-induced activation of NF-κB controls transcription in single Jurkat T cells at the promoters of integrated HIV and the endogenous cytokine gene IL6, which produce only a few transcripts per cell. We tracked TNF-stimulated NF-κB RelA nuclear translocation by live-cell imaging and then quantified transcript number by RNA FISH in the same cell. We found that TNF-induced transcript abundance at 2 h for low- and high-abundance target genes correlates with similar strength with the fold change in nuclear NF-κB. A computational model of TNF-NF-κB signaling, which implements fold-change detection from competition for binding to κB motifs, could reproduce fold-change detection across the experimentally measured range of transcript outputs. However, multiple model parameters affecting transcription had to be simultaneously varied across promoters to maintain fold-change detection while also matching other trends in the single-cell data for low-abundance transcripts. Our results suggest that cells use multiple biological mechanisms to tune transcriptional output while maintaining robustness of NF-κB fold-change detection.

A Supramolecular Strategy toward an Efficient and Selective Capture of Platinum(II) Complexes.

Recovering heavy and precious metals from wastewater is both economically and environmentally attractive. However, a challenge still remains in how to realize the highly selective removal and recovery of a particular metal of interest, such as platinum. Here we experimentally demonstrate a two-dimensional (2D) supramolecular polymer that can serve as a host for the highly selective capture of anionic platinum(II) (PtII) species including its metal-organic complexes and water-soluble ions. This host polymer possesses a 2D honeycomb-like nanostructure noncovalently bridged by cationic alkynylplatinum(II) terpyridine dimers. Anionic PtII guests readily bind to the dimeric PtII building blocks of the internal cavities via electrostatic and specific PtII···PtII interactions. Such unique host-guest interactions have endowed thin membranes comprising highly oriented supramolecular polymers with a versatile ability to selectively recognize and adsorb anionic PtII species over other metal ions in water upon simple filtration.

Semaphorin 3A induces acute changes in membrane excitability in spiral ganglion neurons in vitro.

The development and survival of spiral ganglion neurons (SGNs) are dependent on multiple trophic factors as well as membrane electrical activity. Semaphorins (Sema) constitute a family of membrane-associated and secreted proteins that have garnered significant attention as a potential SGN "navigator" during cochlea development. Previous studies using mutant mice demonstrated that Sema3A plays a role in the SGN pathfinding. The mechanisms, however, by which Sema3A shapes SGNs firing behavior are not known. In these studies, we found that Sema3A plays a novel role in regulating SGN resting membrane potential and excitability. Using dissociated SGN from pre-hearing (P3-P5) and post-hearing mice (P12-P15), we recorded membrane potentials using whole-cell patch clamp recording techniques in apical and basal SGN populations. Recombinant Sema3A was applied to examine the effects on intrinsic membrane properties and action potentials evoked by current injections. Apical and basal SGNs from newborn mice treated with recombinant Sema3A (100 ng/ml) displayed a higher resting membrane potential, higher threshold, decreased amplitude, and prolonged latency and duration of spikes. Although a similar phenomenon was observed in SGNs from post-hearing mice, the resting membrane potential was essentially indistinguishable before and after Sema3A exposure. Sema3A-mediated changes in membrane excitability were associated with a significant decrease in K+ and Ca2+ currents. Sema3A acts through linopirdine-sensitive K+ channels in apical, but not in the basal SGNs. Therefore, Sema3A induces differential effects in SGN membrane excitability that are dependent on age and location, and constitutes an additional early and novel effect of Sema3A SGNs in vitro.