Notch signaling without the APH-2/Nicastrin subunit of Gamma Secretase in C. elegans germline stem cells.

The final step in Notch signaling activation is the transmembrane cleavage of Notch receptor by γ secretase. Thus far, genetic and biochemical evidence indicate that four subunits are essential for γ secretase activity in vivo: presenilin (the catalytic core), APH-1, PEN-2, and APH-2/Nicastrin. Although some γ secretase activity has been detected in APH-2/Nicastrin-deficient mammalian cell lines, the lack of biological relevance for this activity has left the quaternary γ secretase model unchallenged. Here we provide the first example of in vivo Notch signal transduction without APH-2/Nicastrin. The surprising dispensability of APH-2/Nicastrin is observed in C. elegans germline stem cells (GSCs), and contrasts with its essential role in previously described C. elegans Notch signaling events. Depletion of GLP-1/Notch, presenilin, APH-1, or PEN-2 causes a striking loss of GSCs. In contrast, aph-2/Nicastrin mutants maintain GSCs, and exhibit robust and localized expression of the downstream Notch target sygl-1. Interestingly, APH-2/Nicastrin is present in GSCs and becomes essential under conditions of compromised Notch function. Further insight is provided by reconstituting the C. elegans γ secretase complex in yeast, where we find that APH-2/Nicastrin increases, but is not essential for γ secretase activity. Together, our results are most consistent with a revised model of γ secretase in which the APH-2/Nicastrin subunit has a modulatory, rather than obligatory role. We propose that a trimeric presenilin-APH-1-PEN-2 γ secretase complex can provide a low level of γ secretase activity, and that cellular context determines whether or not APH-2/Nicastrin is essential for effective Notch signal transduction.

An HPLC-ESI-QTOF method to analyze polar heteroatomic species in aviation turbine fuel via hydrophilic interaction chromatography.

Aviation turbine fuel is a complex mixture of thousands of compounds. An analytical method using hydrophilic interaction liquid chromatography (HILIC) coupled with electrospray ionization and quadrupole time-of-flight mass spectrometry (ESI-QTOF) was developed for the identification of heteroatomic, polar compounds in aviation turbine fuel. Although compounds containing oxygen, nitrogen, and sulfur functional groups are each found at low levels (<0.1 % by mass) in fuels, their presence can generate significant effects on fuel properties. The HILIC-ESI-QTOF method is a combined separation and detection technique that possesses many advantages including a fast and simple sample preparation-requiring no extraction step therefore ensuring no loss of compounds of interest-and the ability to acquire high-fidelity compound data for chemometric analysis of heteroatomic species in aviation turbine fuel. In the development of the method, it was found that the chromatographic conditions and nature of the injection sample had a significant effect on separation efficiency and repeatability. For a sample dataset optimized using a singular aviation turbine fuel, retention time shift was able to be reduced from 0.4 min to 2.0 % relative standard deviation (RSD) to approximately 0.1 min with RSD of 0.4 % using the newly developed method. In addition, a high number of untargeted molecular features (944) and targeted amines (121) were able to be identified when utilizing optimal method conditions. The specific benefits and limitations of utilizing HILIC techniques with HPLC-ESI-QTOF are also discussed herein. This new method is currently being expanded to include analysis of all heteroatoms and is being applied to real fuel sets. The results of these studies are forthcoming.

High burden of clinically significant adverse events associated with contemporary therapy for pediatric T-cell acute lymphoblastic leukemia/lymphoma.

BACKGROUND: Despite improvements in survival for children with T-cell acute lymphoblastic leukemia and lymphoma (T-ALL/LLy), morbidity remains high. However, data are lacking regarding comprehensive descriptions of clinically relevant adverse events (AEs) experienced during early intensive chemotherapy. PROCEDURE: This single-institution retrospective study evaluated children aged 1-21 years with T-ALL/T-LLy diagnosed from 2010 to 2020. Physician chart abstraction identified and graded 20 clinically relevant AEs. AE rates were analyzed by T-ALL or LLy, minimal residual disease status, induction steroid, and use of antimicrobial prophylaxis. Statistical comparisons used the Kruskal-Wallis test (continuous variables) and Chi-square or Fisher's exact test (categorical variables). RESULTS: The cohort included 120 patients (T-ALL: 88; T-LLy: 32). Most patients experienced AEs during induction (85 out of 120; 70.8%) and consolidation (89 out of 111; 80.2%). Nonsepsis infection was common in induction (26 out of 120; 21.7%) and consolidation (35 out of 111; 31.5%). Patients treated with dexamethasone during induction had significantly higher rates of nonsepsis infection and/or sepsis during consolidation than those who received prednisone (p < .01). CONCLUSIONS: Clinically significant AEs are extremely common during induction and consolidation therapy for patients with T-ALL/LLy. Infectious AEs are particularly prevalent. These results can inform conversations with patients and families and aid in the development of toxicity-related aims in the next generation of, prospective clinical trials in T-ALL/LLy.

Successful Medical-Surgical Management of Intracardiac Thrombosis and Pulmonary Pseudoaneurysms in an Adolescent With Hughes-Stovin Syndrome.

We present an adolescent male with a single intracardiac mass and pulmonary emboli, complicated by peripheral venous thrombosis and subsequent development of pulmonary pseudoaneurysms, leading to diagnosis of Hughes-Stovin syndrome. Remission was achieved with cyclophosphamide, corticosteroids, and pseudoaneurysm resection and maintained with infliximab and methotrexate.

Comparison of Multisystem Inflammatory Syndrome in Children-Related Myocarditis, Classic Viral Myocarditis, and COVID-19 Vaccine-Related Myocarditis in Children.

Background Although rare, classic viral myocarditis in the pediatric population is a disease that carries significant morbidity and mortality. Since 2020, myocarditis has been a common component of multisystem inflammatory syndrome in children (MIS-C) following SARS-CoV-2 infection. In 2021, myocarditis related to mRNA COVID-19 vaccines was recognized as a rare adverse event. This study aims to compare classic, MIS-C, and COVID-19 vaccine-related myocarditis with regard to clinical presentation, course, and outcomes. Methods and Results In this retrospective cohort study, we compared patients aged <21 years hospitalized at our institution with classic viral myocarditis from 2015 to 2019, MIS-C myocarditis from March 2020 to February 2021, and vaccine-related myocarditis from May 2021 to June 2021. Of 201 total participants, 43 patients had classic myocarditis, 149 had MIS-C myocarditis, and 9 had vaccine-related myocarditis. At presentation, ejection fraction was lowest for those with classic myocarditis, with ejection fraction <55% present in 58% of patients. Nearly all patients with MIS-C myocarditis (n=139, 93%) and all patients with vaccine-related myocarditis (n=9, 100%) had normal left ventricular ejection fraction at the time of discharge compared with 70% (n=30) of the classic myocarditis group (P<0.001). At 3 months after discharge, of the 21 children discharged with depressed ejection fraction, none of the 10 children with MIS-C myocarditis had residual dysfunction compared with 3 of the 11 (27%) patients in the classic myocarditis group. Conclusions Compared with classic myocarditis, those with MIS-C myocarditis had better clinical outcomes, including rapid recovery of cardiac function. Patients with vaccine-related myocarditis had prompt resolution of symptoms and improvement of cardiac function.

Transient Global Ventricular Hypertrophy in a Patient With Multisystem Inflammatory Syndrome in Children (MIS-C) Correlated With High-Dose Glucocorticoid Treatment: A Case Report.

Multisystem inflammatory syndrome in children (MIS-C) following SARS-CoV-2 infection has been shown to lead to depressed cardiac function. Standard treatment includes high-dose glucocorticoids (GC). We present the unusual case of a teenager who developed transient echocardiographic global ventricular hypertrophy following GC administration during his treatment for MIS-C, with the resolution of the hypertrophy after cessation of GC.

Quantifying the difference in risk of adverse events by induction treatment regimen in pediatric acute lymphoblastic leukemia.

The differences in overall morbidity by induction treatment regimen for pediatric acute lymphoblastic leukemia (ALL) are unknown. We examined a cohort of children with ALL who received induction chemotherapy between January 2010 and May 2018. We evaluated 20 clinically relevant adverse events (AEs) and readmission and ICU admission rates. Outcomes were compared between standard 3- and 4-drug treatment regimens in multivariate analyses using Cox proportional hazard ratios. Among 486 eligible patients, the risks of sepsis (HR = 2.16, 95% CI = 1.11-4.19), hypoxia (HR = 2.08, 95% CI = 1.03-4.18), hyperbilirubinemia (HR = 2.48, 95% CI = 1.07-5.74), hyperglycemia (HR = 2.65, 95% CI = 1.29-5.42), thromboembolic event (HR = 4.50, 95% CI = 1.30-15.6), and hyponatremia (HR = 7.88, 95% CI = 1.26-49.4) were significantly higher during 4-drug induction. Despite no differences in readmission or ICU admission rates, 4-drug induction patients had greater total inpatient days (12 vs. 4 days; p<.0001). In conclusion, pediatric patients receiving 4-drug induction for ALL experience higher morbidity. These results inform care practices and patient guidance during induction therapy.

Quantification of elemental and total carbon in combustion particulate matter using thermal-oxidative analysis.

The use of a two-step thermal-oxidative analysis (TOA) technique for quantification of the mass of total carbon (TC) and elemental carbon (EC) of turbine engine-borne particulate matter (PM) has been evaluated. This approach could be used in lieu of analysis methods which were developed to characterize diluted PM. This effort is of particular interest as turbine engine PM emissions typically have a higher EC content than ambient aerosols, and filter sample mass loadings can be significantly greater than recommended for existing analysis techniques. Analyses were performed under a pure oxygen environment using a two-step temperature profile; reference carbon and actual PM samples were used to identify appropriate analysis conditions. Thermal gravimetric analysis (TGA) methods were used to provide guidance on the nature of the carbon in several of the materials. This was necessary as a standard reference material does not exist for determination of the EC fraction in PM. The TGA also assisted in identifying an appropriate temperature range for the first-stage of the TOA method. Quantification of TC and EC for turbine engine PM samples using TOA was compared to results obtained using the NIOSH 5040 thermal-optical method. For first-stage TOA temperatures of 350°C and 400°C, excellent agreement between the techniques was observed in both the quantified TC and EC, supporting the viability for using TOA for analysis of turbine engine PM samples. A primary benefit of using TOA for these types of PM samples is that filters with relatively high PM mass loadings (sampled at the emission source) can be readily analyzed. In addition, an entire filter sample can be evaluated, as compared to the use of a filter punch sample for the NIOSH technique. While the feasibility of using a TOA method for engine PM samples has been demonstrated, future studies to estimate potential OC charring and oxidation of EC-type material may provide additional data to assess its impact on the OC/EC fractions for other carbon-type measurements. Implications: This work presents results and procedures of an analytical method for the determination of total and elemental carbon, i.e., TC and EC present in combustion source particulate matter samples. In general, it is shown that the LECO TOA methodology is as reliable and comprehensive as NIOSH 5040 for determining TC and EC carbon types in particulate matter present in turbine emission sources, and should be considered as an alternative. Principles of the methodology, differences, and corresponding agreement with the standard NIOSH 5040 method and TGA analysis are discussed.

RHOA G17V Induces T Follicular Helper Cell Specification and Promotes Lymphomagenesis.

Angioimmunoblastic T cell lymphoma (AITL) is an aggressive tumor derived from malignant transformation of T follicular helper (Tfh) cells. AITL is characterized by loss-of-function mutations in Ten-Eleven Translocation 2 (TET2) epigenetic tumor suppressor and a highly recurrent mutation (p.Gly17Val) in the RHOA small GTPase. Yet, the specific role of RHOA G17V in AITL remains unknown. Expression of Rhoa G17V in CD4+ T cells induces Tfh cell specification; increased proliferation associated with inducible co-stimulator (ICOS) upregulation and increased phosphoinositide 3-kinase (PI3K) and mitogen-activated protein kinase signaling. Moreover, RHOA G17V expression together with Tet2 loss resulted in development of AITL in mice. Importantly, Tet2-/-RHOA G17V tumor proliferation in vivo can be inhibited by ICOS/PI3K-specific blockade, supporting a driving role for ICOS signaling in Tfh cell transformation.

Exopolysaccharide microchannels direct bacterial motility and organize multicellular behavior.

The myxobacteria are a family of soil bacteria that form biofilms of complex architecture, aligned multilayered swarms or fruiting body structures that are simple or branched aggregates containing myxospores. Here, we examined the structural role of matrix exopolysaccharide (EPS) in the organization of these surface-dwelling bacterial cells. Using time-lapse light and fluorescence microscopy, as well as transmission electron microscopy and focused ion beam/scanning electron microscopy (FIB/SEM) electron microscopy, we found that Myxococcus xanthus cell organization in biofilms is dependent on the formation of EPS microchannels. Cells are highly organized within the three-dimensional structure of EPS microchannels that are required for cell alignment and advancement on surfaces. Mutants lacking EPS showed a lack of cell orientation and poor colony migration. Purified, cell-free EPS retains a channel-like structure, and can complement EPS- mutant motility defects. In addition, EPS provides the cooperative structure for fruiting body formation in both the simple mounds of M. xanthus and the complex, tree-like structures of Chondromyces crocatus. We furthermore investigated the possibility that EPS impacts community structure as a shared resource facilitating cooperative migration among closely related isolates of M. xanthus.