Rifaximin plus lactulose versus lactulose alone for reducing the risk of HE recurrence.

BACKGROUND: The aim was to examine rifaximin plus lactulose efficacy in patients with cirrhosis at a risk of developing overt HE who were stratified by important baseline characteristics such as comorbid ascites or diabetes. METHODS: Pooled post hoc subgroup analysis of adults receiving rifaximin 550 mg twice daily plus lactulose or lactulose alone for 6 months in a phase 3 randomized, double-blind trial and a phase 4 open-label trial was conducted. RESULTS AND CONCLUSION: Rifaximin plus lactulose was more efficacious than lactulose alone for reducing the risk of overt HE recurrence and HE-related hospitalization in adults grouped by select baseline disease characteristics.

Plecanatide Improves Abdominal Bloating and Bowel Symptoms of Irritable Bowel Syndrome with Constipation.

BACKGROUND: Bloating is a bothersome symptom in irritable bowel syndrome with constipation (IBS-C). AIM: To evaluate plecanatide efficacy in patients with IBS-C stratified by bloating intensity. METHODS: Pooled phase 3 data (2 randomized, controlled IBS-C trials) from adults treated with plecanatide 3 mg or placebo for 12 weeks were analyzed. Patients were stratified post-hoc by baseline bloating severity (11-point scale: mild [≤ 5] and moderate-to-severe [> 5]). Assessments included change from baseline in bloating, abdominal pain, and complete spontaneous bowel movement (CSBM) frequency. Abdominal pain and bloating composite responders were defined as patients with ≥ 30% improvement from baseline in both bloating and abdominal pain at Week 12. RESULTS: At baseline, 1104/1436 patients with IBS-C (76.9%) reported moderate-to-severe bloating. In the moderate-to-severe bloating subgroup, plecanatide significantly reduced bloating severity versus placebo (least-squares mean change [LSMC]: - 1.7 vs - 1.3; P = 0.002), reduced abdominal pain (- 1.7 vs - 1.3; P = 0.006), and increased CSBM frequency (1.4 vs 0.8; P < 0.0001). In the mild bloating subgroup, significant improvements were observed with plecanatide versus placebo for abdominal pain (LSMC: - 1.3 vs - 1.0; P = 0.046) and CSBM frequency (2.0 vs 1.2; P = 0.003) but not bloating (- 0.9 vs - 0.8; P = 0.28). A significantly greater percentage of patients were abdominal pain and bloating composite responders with plecanatide versus placebo (moderate-to-severe bloating: 33.6% vs 26.8% [P = 0.02]; mild bloating: 38.4% vs 27.2% [P = 0.03]). CONCLUSION: Plecanatide treatment improved IBS-C abdominal and bowel symptoms, including in those who present with moderate-to-severe bloating.

Sulfur-Tuned Main-Group Sb-N-C Catalysts for Selective 2-Electron and 4-Electron Oxygen Reduction.

The selective oxygen reduction reaction (ORR) is important for various energy conversion processes such as the fuel cells and metal-air batteries for the 4e- pathway and hydrogen peroxide (H2O2) electrosynthesis for the 2e- pathway. However, it remains a challenge to tune the ORR selectivity of a catalyst in a controllable manner. Herein, an efficient strategy for introducing sulfur dopants to regulate the ORR selectivity of main-group Sb-N-C single-atom catalysts  is reported. Significantly, Sb-N-C with the highest sulfur content follows a 2e- pathway with high H2O2 selectivity (96.8%) and remarkable mass activity (96.1 A g-1 at 0.65 V), while the sister catalyst with the lowest sulfur content directs a 4e- pathway with a half-wave potential (E1/2 = 0.89 V) that is more positive than commercial Pt/C. In addition, practical applications for these two 2e-/4e- ORR catalysts are demonstrated by bulk H2O2 electrosynthesis for the degradation of organic pollutants and a high-power zinc-air battery, respectively. Combined experimental and theoretical studies reveal that the excellent selectivity for the sulfurized Sb-N-Cs is attributed to the optimal adsorption-desorption of the ORR intermediates realized through the electronic structure modulation by the sulfur dopants.

Ultrasmall and Highly Dispersed Pt Entities Deposited on Mesoporous N-doped Carbon Nanospheres by Pulsed CVD for Improved HER.

Vapor-based deposition techniques are emerging approaches for the design of carbon-supported metal powder electrocatalysts with tailored catalyst entities, sizes, and dispersions. Herein, a pulsed CVD (Pt-pCVD) approach is employed to deposit different Pt entities on mesoporous N-doped carbon (MPNC) nanospheres to design high-performance hydrogen evolution reaction (HER) electrocatalysts. The influence of consecutive precursor pulse number (50-250) and deposition temperature (225-300 °C) are investigated. The Pt-pCVD process results in highly dispersed ultrasmall Pt clusters (≈1 nm in size) and Pt single atoms, while under certain conditions few larger Pt nanoparticles are formed. The best MPNC-Pt-pCVD electrocatalyst prepared in this work (250 pulses, 250 °C) reveals a Pt HER mass activity of 22.2 ± 1.2 A mg-1 Pt at -50 mV versus the reversible hydrogen electrode (RHE), thereby outperforming a commercially available Pt/C electrocatalyst by 40% as a result of the increased Pt utilization. Remarkably, after optimization of the Pt electrode loading, an ultrahigh Pt mass activity of 56 ± 2 A mg-1 Pt at -50 mV versus RHE is found, which is among the highest Pt mass activities of Pt single atom and cluster-based electrocatalysts reported so far.

Controlled Biocatalytic Synthesis of a Metal Nanoparticle-Enzyme Hybrid: Demonstration for Catalytic H2-driven NADH Recycling.

Here we demonstrate the preparation of enzyme-metal biohybrids of NAD+ reductase with biocatalytically-synthesised small gold nanoparticles (NPs, <10 nm) and core-shell gold-platinum NPs for tandem catalysis. Despite the variety of methods available for NP synthesis, there remains a need for more sustainable strategies which also give precise control over the shape and size of the metal NPs for applications in catalysis, biomedical devices, and electronics. We demonstrate facile biosynthesis of spherical, highly uniform, gold NPs under mild conditions using an isolated enzyme moiety, an NAD+ reductase, to reduce metal salts while oxidising a nicotinamide-containing cofactor. By subsequently introducing platinum salts, we show that core-shell Au@Pt NPs can then be formed. Catalytic function of these enzyme-Au@Pt NP hybrids was demonstrated for H2-driven NADH recycling to support enantioselective ketone reduction by an NADH-dependent alcohol dehydrogenase.

Serum Ammonia Levels Do Not Correlate With Overt Hepatic Encephalopathy Severity in Hospitalized Patients With Cirrhosis.

Although ammonia is involved in the pathophysiology of hepatic encephalopathy (HE), the use of ammonia levels in clinical practice is problematic.1-3 For example, in a study of 551 patients with overt HE (OHE) receiving lactulose who had ammonia levels tested, only 60% had an increased ammonia level (defined as >72 µmol/L).2 Overall, there was no correlation observed between lactulose dose and whether ammonia levels were obtained (ie, presence/absence of increased ammonia level did not guide therapy), or between time to OHE resolution and ammonia levels.2 Additionally, there is substantial interlaboratory variability in sample handling and processing, which may affect ammonia measurements.4.

A novel bioinformatic method for the identification of antimicrobial peptides in metagenomes.

AIMS: This study aimed to develop a new bioinformatic approach for the identification of novel antimicrobial peptides (AMPs), which did not depend on sequence similarity to known AMPs held within databases, but on structural mimicry of another antimicrobial compound, in this case an ultrashort, synthetic, cationic lipopeptide (C12-OOWW-NH2). METHODS AND RESULTS: When applied to a collection of metagenomic datasets, our outlined bioinformatic method successfully identified several short (8-10aa) functional AMPs, the activity of which was verified via disk diffusion and minimum inhibitory concentration assays against a panel of 12 bacterial strains. Some peptides had activity comparable to, or in some cases, greater than, those from published studies that identified AMPs using more conventional methods. We also explored the effects of modifications, including extension of the peptides, observing an activity peak at 9-12aa. Additionally, the inclusion of a C-terminal amide enhanced activity in most cases. Our most promising candidate (named PB2-10aa-NH2) was thermally stable, lipid-soluble, and possessed synergistic activity with ethanol but not with a conventional antibiotic (streptomycin). CONCLUSIONS: While several bioinformatic methods exist to predict AMPs, the approach outlined here is much simpler and can be used to quickly scan huge datasets. Searching for peptide sequences bearing structural similarity to other antimicrobial compounds may present a further opportunity to identify novel AMPs with clinical relevance, and provide a meaningful contribution to the pressing global issue of AMR.

Designer Small-Molecule Control System Based on Minocycline-Induced Disruption of Protein-Protein Interaction.

A versatile, safe, and effective small-molecule control system is highly desirable for clinical cell therapy applications. Therefore, we developed a two-component small-molecule control system based on the disruption of protein-protein interactions using minocycline, an FDA-approved antibiotic with wide availability, excellent biodistribution, and low toxicity. The system comprises an anti-minocycline single-domain antibody (sdAb) and a minocycline-displaceable cyclic peptide. Here, we show how this versatile system can be applied to OFF-switch split CAR systems (MinoCAR) and universal CAR adaptors (MinoUniCAR) with reversible, transient, and dose-dependent suppression; to a tunable T cell activation module based on MyD88/CD40 signaling; to a controllable cellular payload secretion system based on IL12 KDEL retention; and as a cell/cell inducible junction. This work represents an important step forward in the development of a remote-controlled system to precisely control the timing, intensity, and safety of therapeutic interventions.

Xylitol for the prevention of acute otitis media episodes in children aged 1-5 years: a randomised controlled trial.

OBJECTIVE: To investigate the regular use of xylitol, compared with sorbitol, to prevent acute otitis media (AOM), upper respiratory tract infections (URTIs) and dental caries. DESIGN: Blinded randomised controlled trial with a 6-month study period. SETTING: Enrolment took place at 11 primary care practices in Ontario, Canada. PATIENTS: Children aged 1-5 years who did not use xylitol or sorbitol at enrolment. INTERVENTIONS: Children were randomly assigned to use a placebo syrup with sorbitol or xylitol syrup two times per day for 6 months. MAIN OUTCOME MEASURES: Primary outcome was the number of clinician-diagnosed AOM episodes over 6 months. Secondary outcomes were caregiver-reported URTIs and dental caries. RESULTS: Among the 250 randomised children, the mean (SD) age was 38±14 months and there were 124 girls (50%). There were three clinician-diagnosed AOM episodes in the 125 placebo group participants and six in the 125 xylitol group participants (OR 2.04; 95% CI 0.43, 12.92; p=0.50). There was no difference in number of caregiver-reported URTI episodes (rate ratio (RR) 0.88; 95% CI 0.70, 1.11) between the placebo (4.2 per participant over 6 months; 95% CI 3.6, 5.0) and xylitol (3.7; 95% CI 3.2, 4.4) groups. Dental caries were reported for four participants in the placebo group and two in the xylitol group (OR 0.42; 95% CI 0.04, 3.05; p=0.42). In a post-hoc analysis of URTIs during the COVID-19 pandemic, the rate among the 59 participants receiving placebo was 2.3 per participant over 6 months (95% CI 1.8, 3.0) and for the 55 receiving xylitol, 1.3 over 6 months (95% CI 0.92, 1.82; RR 0.56; 95% CI 0.36, 0.87). The most common adverse event was diarrhoea (28% with placebo; 34% with xylitol). CONCLUSIONS: Regular use of xylitol did not prevent AOM, URTIs or dental caries in a trial with limited statistical power. A post-hoc analysis indicated that URTIs were less common with xylitol exposure during the COVID-19 pandemic, but this finding could be spurious. TRIAL REGISTRATION NUMBER: NCT03055091.

Tailoring C─N Containing Compounds into Carbon Nanomaterials with Tunable Morphologies for Electrocatalytic Applications.

Carbon materials with unique sp2 -hybridization are extensively researched for catalytic applications due to their excellent conductivity and tunable physicochemical properties. However, the development of economic approaches to tailoring carbon materials into desired morphologies remains a challenge. Herein, a convenient "bottom-up" strategy by pyrolysis of graphitic carbon nitride (g-C3 N4 ) (or other carbon/nitrogen (C, N)-enriched compounds) together with selected metal salts and molecules is reported for the construction of different carbon-based catalysts with tunable morphologies, including carbon nano-balls, carbon nanotubes, nitrogen/sulfur (S, N) doped-carbon nanosheets, and single-atom catalysts, supported by carbon layers. The catalysts are systematically investigated through various microscopic, spectroscopic, and diffraction methods and they demonstrate promising and broad applications in electrocatalysis such as in the oxygen reduction reaction and water splitting. Mechanistic monitoring of the synthesis process through online thermogravimetric-gas chromatography-mass spectrometry measurements indicates that the release of C─N-related moieties, such as dicyan, plays a key role in the growth of carbon products. This enables to successfully predict other widely available precursor compounds beyond g-C3 N4 such as caffeine, melamine, and urea. This work develops a novel and economic strategy to generate morphologically diverse carbon-based catalysts and provides new, essential insights into the growth mechanism of carbon nanomaterials syntheses.

Parents' Understanding About Children's Bullying: Fall ConsumerStyles Survey, United States, 2017, 2018, and 2019.

The purpose of this study was to explore U.S. parents' and caregivers' understanding about children's bullying-what bullying is and how to address it. We analyzed 2017, 2018, and 2019 Fall ConsumerStyles online panel survey data from U.S. parents/caregivers of children ages 10 to 17 years (N = 1,516), including 20 items representing statements consistent or inconsistent with the bullying prevention evidence and best practices. Percentage of endorsement for each item and a summary measure of understanding about bullying were calculated. The association between low overall understanding about bullying and sociodemographic characteristics was explored. Most parents identified bullying as harmful (77%), repetitive (63%), and involving power imbalance (51%). At least half of parents answered 13 or more items (20 total) consistent with the bullying prevention evidence or best practices. Being male, non-Hispanic Black or Hispanic, having high school or less education, and small household size were associated with higher odds of low overall understanding about bullying. Awareness of parents' understanding about bullying and how to appropriately address it is vital for bullying prevention. Findings can inform the strategic development of bullying prevention health messages for parents.

Perceived Effectiveness of COVID-19 Preventive Practices and Behavioral Intention: Survey of a Representative Adult Sample in the United States.

BACKGROUND: Using existing models of behavioral health promotion, specifically the Extended Parallel Process Model, previous research has identified factors that may impact engagement in preventive health behaviors during the COVID-19 pandemic such as perceived threat, perceived susceptibility to the threat, perceived severity, and perceived efficacy. OBJECTIVE: This study aims to examine the role of perceived effectiveness of COVID-19 preventive behaviors, perceived susceptibility, perceived threat, and perceived severity of COVID-19 in participants' intentions to engage in Centers for Disease Control (CDC)-recommended individual health behaviors in the first year of the pandemic. METHODS: In October 2020, a representative sample of 506 US adults completed a web-based survey through the RAND American Life Panel. RESULTS: The study primarily found that participants who perceived that CDC-recommended health practices were effective had stronger intentions to engage in those practices. The second strongest correlate was participants' perceived severity of COVID-19 across the United States. Perceived effectiveness of recommended practices accounted for the largest variance in behavioral intention. However, analysis of individual behaviors indicated a mismatch in the behaviors perceived to be the most effective (avoiding sick people and mask-wearing) and those participants indicated intention to engage in (throwing away used tissues, avoiding sick people, and coughing into their elbows) in the next 30 days. CONCLUSIONS: The authors recommend tailoring public health messaging to address the perceived threat of COVID-19 and self-efficacy. Thus, health promotion efforts should emphasize the effectiveness of CDC-recommended practices while highlighting the pandemic's severity. Additionally, rebuilding trust in public health messaging and messengers is necessary to increase perceived self-efficacy. As the COVID-19 pandemic continues, health messaging must continue to promote and build trust in CDC-recommended health practices and educate regarding the efficacy of vaccination and other preventive behaviors.

Large-scale manufacturing of base-edited chimeric antigen receptor T cells.

Base editing is a revolutionary gene-editing technique enabling the introduction of point mutations into the genome without generating detrimental DNA double-stranded breaks. Base-editing enzymes are commonly delivered in the form of modified linear messenger RNA (mRNA) that is costly to produce. Here, we address this problem by developing a simple protocol for manufacturing base-edited cells using circular RNA (circRNA), which is less expensive to synthesize. Compared with linear mRNA, higher editing efficiencies were achieved with circRNA, enabling an 8-fold reduction in the amount of RNA required. We used this protocol to manufacture a clinical dose (1 × 108 cells) of base-edited chimeric antigen receptor (CAR) T cells lacking expression of the inhibitory receptor, PD-1. Editing efficiencies of up to 86% were obtained using 0.25 µg circRNA/1 × 106 cells. Increased editing efficiencies with circRNA were attributed to more efficient translation. These results suggest that circRNA, which is less expensive to produce than linear mRNA, is a viable option for reducing the cost of manufacturing base-edited cells at scale.

An Unusual Cause of Fever, Neck Pain, and Neck Stiffness: Acute Calcific Tendinitis of the Longus Colli Muscle.

BACKGROUND: Acute calcific tendinitis (ACT) of the longus colli muscle (LCM) is an inflammatory response due to deposition of calcium hydroxyapatite crystals. It is typically correlated with whiplash and overuse injuries. A common presentation of this inflammatory response is acute but progressive neck pain. It is a rare but important cause of neck pain that should be considered on a differential diagnosis when distinguishing between life-threatening conditions and non-life-threatening causes of neck pain. CASE REPORT: A 51-year-old woman presented to the emergency department (ED) reporting a mild sore throat that progressed to acute neck pain and stiffness. She also reported fatigue, fever, myalgias, and nausea. In the ED, the patient was tachycardic, hypertensive, and mildly febrile with normal oxygen saturation. Examination revealed meningismus and was negative for lymphadenopathy, oropharyngeal findings, and neurologic deficits. Laboratory studies were significant for leukocytosis. Computed tomography (CT) neck was obtained and was notable for calcification of the superior left longus colli muscle with prevertebral and retropharyngeal space edema along the muscle body. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: ACT of the LCM is a benign, self-limited condition that can present with features overlapping emergent causes of acute neck pain. Correct diagnosis relies on characteristic radiographic findings on CT. Fortunately, patients may be discharged home with a short course of anti-inflammatories and corticosteroids with near-complete resolution of symptoms. Emergency physicians, therefore, can rule out life-threatening causes of neck pain, while also making a definitive diagnosis and initiating effective management for this pathology.

Measurement of Atomic Modulation Direction Using the Azimuthal Variation of First-Order Laue Zone Electron Diffraction.

We show that diffraction intensity into the first-order Laue zone (FOLZ) of a crystal can have a strong azimuthal dependence, where this FOLZ ring appears solely because of unidirectional atom position modulation. Such a modulation was already known to cause the appearance of elliptical columns in atom-resolution images, but we show that measurement of the angle via four-dimensional scanning transmission electron microscopy (4DSTEM) is far more reliable and allows the measurement of the modulation direction with a precision of about 1° and an accuracy of about 3°. This method could be very powerful in characterizing atomic structures in three dimensions by 4DSTEM, especially in cases where the structure is found only in nanoscale regions or crystals.

Mapping Nanoscale Electrostatic Field Fluctuations around Graphene Dislocation Cores Using Four-Dimensional Scanning Transmission Electron Microscopy (4D-STEM).

Defects in crystalline lattices cause modulation of the atomic density, and this leads to variations in the associated electrostatics at the nanoscale. Mapping these spatially varying charge fluctuations using transmission electron microscopy has typically been challenging due to complicated contrast transfer inherent to conventional phase contrast imaging. To overcome this, we used four-dimensional scanning transmission electron microscopy (4D-STEM) to measure electrostatic fields near point dislocations in a monolayer. The asymmetry of the atomic density in a (1,0) edge dislocation core in graphene yields a local enhancement of the electric field in part of the dislocation core. Through experiment and simulation, the increased electric field magnitude is shown to arise from "long-range" interactions from beyond the nearest atomic neighbor. These results provide insights into the use of 4D-STEM to quantify electrostatics in thin materials and map out the lateral potential variations that are important for molecular and atomic bonding through Coulombic interactions.

Enhancing CAR T-cell Therapy Using Fab-Based Constitutively Heterodimeric Cytokine Receptors.

Adoptive T-cell therapy aims to achieve lasting tumor clearance, requiring enhanced engraftment and survival of the immune cells. Cytokines are paramount modulators of T-cell survival and proliferation. Cytokine receptors signal via ligand-induced dimerization, and this principle has been hijacked utilizing nonnative dimerization domains. A major limitation of current technologies resides in the absence of a module that recapitulates the natural cytokine receptor heterodimeric pairing. To circumvent this, we created a new engineered cytokine receptor able to constitutively recreate receptor-heterodimer utilizing the heterodimerization domain derived from the IgG1 antibody (dFab_CCR). We found that the signal delivered by the dFab_CCR-IL2 proficiently mimicked the cytokine receptor heterodimerization, with transcriptomic signatures like those obtained by activation of the native IL2 receptor. Moreover, we found that this dimerization structure was agnostic, efficiently activating signaling through four cytokine receptor families. Using a combination of in vivo and in vitro screening approaches, we characterized a library of 18 dFab_CCRs coexpressed with a clinically relevant solid tumor-specific GD2-specific chimeric antigen receptor (CAR). Based on this characterization, we suggest that the coexpression of either the common ß-chain GMCSF or the IL18 dFab_CCRs is optimal to improve CAR T-cell expansion, engraftment, and efficacy. Our results demonstrate how Fab dimerization is efficient and versatile in recapitulating a cytokine receptor heterodimerization signal. This module could be applied for the enhancement of adoptive T-cell therapies, as well as therapies based on other immune cell types. Furthermore, these results provide a choice of cytokine signal to incorporate with adoptive T-cell therapies.

Novel Fas-TNFR chimeras that prevent Fas ligand-mediated kill and signal synergistically to enhance CAR T cell efficacy.

The hostile tumor microenvironment limits the efficacy of adoptive cell therapies. Activation of the Fas death receptor initiates apoptosis and disrupting these receptors could be key to increasing CAR T cell efficacy. We screened a library of Fas-TNFR proteins identifying several novel chimeras that not only prevented Fas ligand-mediated kill, but also enhanced CAR T cell efficacy by signaling synergistically with the CAR. Upon binding Fas ligand, Fas-CD40 activated the NF-κB pathway, inducing greatest proliferation and IFN-γ release out of all Fas-TNFRs tested. Fas-CD40 induced profound transcriptional modifications, particularly genes relating to the cell cycle, metabolism, and chemokine signaling. Co-expression of Fas-CD40 with either 4-1BB- or CD28-containing CARs increased in vitro efficacy by augmenting CAR T cell proliferation and cancer target cytotoxicity, and enhanced tumor killing and overall mouse survival in vivo. Functional activity of the Fas-TNFRs were dependent on the co-stimulatory domain within the CAR, highlighting crosstalk between signaling pathways. Furthermore, we show that a major source for Fas-TNFR activation derives from CAR T cells themselves via activation-induced Fas ligand upregulation, highlighting a universal role of Fas-TNFRs in augmenting CAR T cell responses. We have identified Fas-CD40 as the optimal chimera for overcoming Fas ligand-mediated kill and enhancing CAR T cell efficacy.

Joint British Societies' position statement on bullying, harassment and discrimination in cardiology.

Inappropriate behaviour is an umbrella term including discrimination, harassment and bullying. This includes both actions and language and can affect any member of the cardiovascular workforce/team. Evidence has suggested that such behaviour is regularly experienced within UK cardiology departments, where inappropriate behaviour may represent longstanding cultural and practice issues within the unit. Inappropriate behaviour has negative effects on the workforce community as a whole, including impacts on recruitment and retention of staff and patient care. While only some members of the cardiology team may be directly impacted by inappropriate behaviour in individual departments, a wider group are significantly impacted as bystanders. As such, improving the culture and professional behaviours within UK cardiology departments is of paramount importance. As a negative workplace culture is felt to be a major driver of inappropriate behaviour, all members of the cardiovascular team have a role to play in ensuring a positive workplace culture is developed. Episodes of inappropriate behaviour should be challenged by cardiovascular team members. Informal feedback may be appropriate where 'one-off' episodes of inappropriate behaviour occur, but serious events or repeated behaviour should be escalated following formal human resources protocols.

School Connectedness and Risk Behaviors and Experiences Among High School Students - Youth Risk Behavior Survey, United States, 2021.

School connectedness, defined as students' belief that adults and peers in their school care about their learning as well as about them as persons, has been linked to positive educational, behavioral, and health outcomes in adolescence and into adulthood. Data from the 2021 nationally representative Youth Risk Behavior Survey, conducted during the COVID-19 pandemic, were used to estimate prevalence of students' perception of school connectedness and examine associations between school connectedness and seven risk behaviors and experiences: poor mental health, marijuana use, prescription opioid misuse, sexual intercourse, unprotected sex, experiencing forced sex, and missing school because of feeling unsafe. Prevalence estimates were generated and pairwise t-tests were used to detect differences among student subpopulations by sex, grade, race and ethnicity, and sexual identity; Wald chi-square tests were used to detect differences in risk behaviors by level of connectedness within a subpopulation. Logistic regression models were used to estimate prevalence ratios comparing the prevalence of risk behaviors and experiences of students with high connectedness with students with low connectedness, stratified by demographics. During 2021, 61.5% of U.S. high school students reported feeling connected to others at school. In addition, school connectedness was associated with lower prevalence of every risk behavior and experience examined in this study, although certain associations differed by race and ethnicity and sexual identity (e.g., school connectedness was associated with better mental health outcomes for youths with heterosexual, bisexual, and questioning or other sexual identities, but not for youths who identified as lesbian or gay). These findings can guide public health interventions that promote youth well-being by creating school environments where all youths have a sense of belonging and feel they are cared for and supported.