Internal Catalysis in Dynamic Hydrogels with Associative Thioester Cross-Links.

Thioesters are an essential functional group in biosynthetic pathways, which has motivated their development as reactive handles in probes and peptide assembly. Thioester exchange is typically accelerated by catalysts or elevated pH. Here, we report the use of bifunctional aromatic thioesters as dynamic covalent cross-links in hydrogels, demonstrating that at physiologic pH in aqueous conditions, transthioesterification facilitates stress relaxation on the time scale of hundreds of seconds. We show that intramolecular hydrogen bonding is responsible for accelerated exchange, evident in both molecular kinetics and macromolecular stress relaxation. Drawing from concepts in the vitrimer literature, this system exemplifies how dynamic cross-links that exchange through an associative mechanism enable tunable stress relaxation without altering stiffness.

Caregiver reactions to babbling organize turn-taking interactions: Facilitative effects of vocal versus non-vocal responses.

Turn-taking interactions are foundational to the development of social, communicative, and cognitive skills. In infants, vocal turn-taking experience is predictive of infants' socioemotional and language development. However, different forms of turn-taking interactions may have different effects on infant vocalizing. It is presently unknown how caregiver vocal, non-vocal and multimodal responses to infant vocalizations compare in extending caregiver-infant vocal turn-taking bouts. In bouts that begin with an infant vocalization, responses that maintain versus change the communicative modality may differentially affect the likelihood of further infant vocalizing. No studies have examined how caregiver response modalities that either matched or differed from the infant acoustic (vocal) modality might affect the temporal structure of vocal turn-taking beyond the initial serve-and-return exchanges. We video-recorded free-play sessions of 51 caregivers with their 9-month-old infants. Caregivers responded to babbling most often with vocalizations. In turn, caregiver vocal responses were significantly more likely to elicit subsequent infant babbling. Bouts following an initial caregiver vocal response contained significantly more turns than those following a non-vocal or multimodal response. Thus prelinguistic turn-taking is sensitive to the modality of caregivers' responses. Future research should investigate if such sensitivity is grounded in attentional constraints, which may influence the structure of turn-taking interactions.

Developmental cascades of vocal turn-taking connect prelinguistic vocalizing with early language.

Conversational turn-taking is ubiquitously found in caregiver-infant interactions, and robustly predictive of infant communicative development. Over the first year, infants take quick adult-like vocal turns with caregivers. Many studies have documented the consistency of caregiver responsiveness and its influence on infant rapid language growth. However, few have examined how caregiver responsiveness facilitates extended vocal turn-taking in real-time with infants over the first year. The influence of prelinguistic vocal turn-taking on the emergence of language has also been under-investigated. We analyzed free-play sessions of 30 caregivers and their infants at both 5 and 10 months, and obtained infant language outcomes at 18 months. We examined the developmental consistency (group-level continuity and dyad-order stability) and change of infant volubility, caregiver responses to babbling in vocal, non-vocal and multimodal modalities, and the influence of modality on caregiver-infant vocal turn-taking. Caregiver contingent responsiveness to infant babbling at 5 months predicted vocal turn-taking at 10 months. Developmental increases in prelinguistic vocalizing and vocal turn-taking from 5 to 10 months predicted infant language outcomes at 18 months. At both 5 and 10 months, caregiver vocal responses were more effective in extending turn-taking than non-vocal or multimodal responses. In summary, prelinguistic vocal turn-taking, facilitated by caregiver vocal responsiveness, is positively related to the emergence of early language.

The distributional and embodied contexts of verbs in caregiver-infant interactions.

The process by which infants learn verbs through daily social interactions is not well-understood. This study investigated caregivers' use of verbs, which have highly abstract meanings, during unscripted toy-play. We examined how verbs co-occurred with distributional and embodied factors including pronouns, caregivers' manual actions, and infants' locomotion, gaze, and object-touching. Object-action verbs were used significantly more often during caregiver-infant joint attention interactions. Movement and cognition verbs showed distinct co-occurrences with different contexts. Cognition and volition verbs were differentiated by pronouns. These findings provide evidence for how verb acquisition may be supported by the distributional and embodied contexts in caregiver-infant interactions.

Tailoring Dynamic Hydrogels by Controlling Associative Exchange Rates.

Dithioalkylidenes are a newly-developed class of conjugate acceptors that undergo thiol exchange via an associative mechanism, enabling decoupling of key material properties for sustainability, biomedical, and sensing applications. Here, we show that the exchange rate is highly sensitive to the structure of the acceptor and tunable over four orders of magnitude in aqueous environments. Cyclic acceptors exchange rapidly, from 0.95 to 15.6 M-1s-1, while acyclic acceptors exchange between 3.77x10-3 and 2.17x10-2 M-1s-1. Computational, spectroscopic, and structural data suggest that cyclic acceptors are more reactive than their acyclic counterparts because of resonance stabilization of the tetrahedral exchange intermediate. We parametrize molecular reactivity with respect to computed descriptors of the electrophilic site and leverage this insight to design a compound with intermediate characteristics. Lastly, we incorporate this dynamic bond into hydrogels and demonstrate that the characteristic stress relaxation time (τ) is directly proportional to molecular kex.

Definitive Treatment of Brain Metastases From a Neuroendocrine Tumor With Peptide Receptor Radionuclide Therapy With 177Lutetium DOTATATE: A Case Report.

Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) are rare malignancies that arise from secretory endocrine cells of the gastroenteropancreatic system. Clinical outcomes have improved for patients with GEP-NETs due to the development and recent FDA approval of 177Lutetium DOTATATE. However, the response of brain metastases from GEP-NETs from 177Lutetium DOTATATE is unreported. We present the case of an 81-year-old man with low-grade small bowel GEP-NET with liver and brain metastases treated with a total of six cycles of 177Lutetium DOTATATE. With over three years of follow-up from his initial treatment, his brain metastases have had complete or partial responses, with no need for brain radiotherapy or radiosurgery.

Systematic Review of Radiology Residency Artificial Intelligence Curricula: Preparing Future Radiologists for the Artificial Intelligence Era.

OBJECTIVE: Although educating radiology trainees about artificial intelligence (AI) has become increasingly emphasized, the types of AI educational curricula are not well understood. We performed a systematic review of original studies describing curricula used to teach AI concepts and practical applications for radiology residents and fellows. MATERIALS AND METHODS: We performed a PubMed search for original studies published as of July 22, 2022, describing AI curricula geared toward radiology residents or fellows. Studies meeting inclusion criteria were evaluated for curricula design, implementation details, and outcomes. Descriptive statistics were used to summarize these curricula. RESULTS: Five studies were included describing an AI curriculum, all geared toward radiology residents. All five curricula were led by radiologists, mostly by individual academic radiology departments (4; 80%) with one led by the ACR Resident and Fellow Section. Curricula design included didactic sessions (5; 100%), assigned readings (4; 80%), hands-on learning (3; 60%), and journal clubs (3; 60%); only one had individualized learning plans. All four studies that evaluated the impact of the curricula on participants' knowledge or attitudes showed positive effects. DISCUSSION: Amid increasing recognition of the importance of AI education for radiologists-in-training, several AI curricula for radiology residents have been implemented. Although curricula designs varied and it is unclear if one type is superior, they have had a positive impact on residents' knowledge and attitudes toward AI. As AI becomes increasingly adopted in radiology, these curricula serve as models for other departments and programs to develop AI educational initiatives to prepare the next generation of radiologists for the AI era.

Candida albicans-specific Th17 cell-mediated response contributes to alcohol-associated liver disease.

Alcohol-associated liver disease is accompanied by intestinal mycobiome dysbiosis, yet the impacts on liver disease are unclear. We demonstrate that Candida albicans-specific T helper 17 (Th17) cells are increased in circulation and present in the liver of patients with alcohol-associated liver disease. Chronic ethanol administration in mice causes migration of Candida albicans (C. albicans)-reactive Th17 cells from the intestine to the liver. The antifungal agent nystatin decreased C. albicans-specific Th17 cells in the liver and reduced ethanol-induced liver disease in mice. Transgenic mice expressing T cell receptors (TCRs) reactive to Candida antigens developed more severe ethanol-induced liver disease than transgene-negative littermates. Adoptively transferring Candida-specific TCR transgenic T cells or polyclonal C. albicans-primed T cells exacerbated ethanol-induced liver disease in wild-type mice. Interleukin-17 (IL-17) receptor A signaling in Kupffer cells was required for the effects of polyclonal C. albicans-primed T cells. Our findings indicate that ethanol increases C. albicans-specific Th17 cells, which contribute to alcohol-associated liver disease.

Islet-specific CD8+ T cells gain effector function in the gut lymphoid tissues via bystander activation not molecular mimicry.

Type 1 diabetes (T1D) is caused by aberrant activation of autoreactive T cells specific for the islet beta cells. How islet-specific T cells evade tolerance to become effector T cells is unknown, but it is believed that an altered gut microbiota plays a role. Possible mechanisms include bystander activation of autoreactive T cells in the gut or "molecular mimicry" from cross-reactivity between gut microbiota-derived peptides and islet-derived epitopes. To investigate these mechanisms, we use two islet-specific CD8+ T cell clones and the non-obese diabetic mouse model of type 1 diabetes. Both insulin-specific G9C8 cells and IGRP-specific 8.3 cells underwent early activation and proliferation in the pancreatic draining lymph nodes but not in the Peyer's patches or mesenteric lymph nodes. Mutation of the endogenous epitope for G9C8 cells abolished their CD69 upregulation and proliferation, ruling out G9C8 cell activation by a gut microbiota derived peptide and molecular mimicry. However, previously activated islet-specific effector memory cells but not naïve cells migrated into the Peyer's patches where they increased their cytotoxic function. Oral delivery of butyrate, a microbiota derived anti-inflammatory metabolite, reduced IGRP-specific cytotoxic function. Thus, while initial activation of islet-specific CD8+ T cells occurred in the pancreatic lymph nodes, activated cells trafficked through the gut lymphoid tissues where they gained additional effector function via non-specific bystander activation influenced by the gut microbiota.

Structure-Reactivity-Property Relationships in Covalent Adaptable Networks.

Polymer networks built out of dynamic covalent bonds offer the potential to translate the control and tunability of chemical reactions to macroscopic physical properties. Under conditions at which these reactions occur, the topology of covalent adaptable networks (CANs) can rearrange, meaning that they can flow, self-heal, be remolded, and respond to stimuli. Materials with these properties are necessary to fields ranging from sustainability to tissue engineering; thus the conditions and time scale of network rearrangement must be compatible with the intended use. The mechanical properties of CANs are based on the thermodynamics and kinetics of their constituent bonds. Therefore, strategies are needed that connect the molecular and macroscopic worlds. In this Perspective, we analyze structure-reactivity-property relationships for several classes of CANs, illustrating both general design principles and the predictive potential of linear free energy relationships (LFERs) applied to CANs. We discuss opportunities in the field to develop quantitative structure-reactivity-property relationships and open challenges.

Metabolic Injury of Hepatocytes Promotes Progression of NAFLD and AALD.

Nonalcoholic liver disease is a component of metabolic syndrome associated with obesity, insulin resistance, and hyperlipidemia. Excessive alcohol consumption may accelerate the progression of steatosis, steatohepatitis, and fibrosis. While simple steatosis is considered a benign condition, nonalcoholic steatohepatitis with inflammation and fibrosis may progress to cirrhosis, liver failure, and hepatocellular cancer. Studies in rodent experimental models and primary cell cultures have demonstrated several common cellular and molecular mechanisms in the pathogenesis and regression of liver fibrosis. Chronic injury and death of hepatocytes cause the recruitment of myeloid cells, secretion of inflammatory and fibrogenic cytokines, and activation of myofibroblasts, resulting in liver fibrosis. In this review, we discuss the role of metabolically injured hepatocytes in the pathogenesis of nonalcoholic steatohepatitis and alcohol-associated liver disease. Specifically, the role of chemokine production and de novo lipogenesis in the development of steatotic hepatocytes and the pathways of steatosis regulation are discussed.

The Field of Cell Competition Comes of Age: Semantics and Technological Synergy.

Stem cells experience many selective pressures which shape their cellular populations, potentially pushing them to skew towards dominance of a few break-through clones. An evolutionarily conserved answer to curb these aberrant selective pressures is cell competition, the elimination of a subset of cells by their neighbours in a seemingly homogenous population. Cell competition in mammalian systems is a relatively recent discovery that has now been observed across many tissue systems, such as embryonic, haematopoietic, intestinal, and epithelial compartments. With this rapidly growing field, there is a need to revisit and standardize the terminology used, much of which has been co-opted from evolutionary biology. Further, the implications of cell competition across biological scales in organisms have been difficult to capture. In this review, we make three key points. One, we propose new nomenclature to standardize concepts across dispersed studies of different types of competition, each of which currently use the same terminology to describe different phenomena. Second, we highlight the challenges in capturing information flow across biological scales. Third, we challenge the field to incorporate next generation technologies into the cell competition toolkit to bridge these gaps. As the field of cell competition matures, synergy between cutting edge tools will help elucidate the molecular events which shape cellular growth and death dynamics, allowing a deeper examination of this evolutionarily conserved mechanism at the core of multicellularity.

Epigenetic maintenance strategies after allogeneic stem cell transplantation in acute myeloid leukemia.

Acute myeloid leukemia (AML) is an aggressive blood malignancy characterized by the accumulation of immature blood cells that can severely impede the normal functions of the hematopoietic system. AML still has a poor 5-year survival rate of around 30%, and efforts to develop novel targeted therapies have been met with challenges. Allogeneic hematopoietic stem cell transplantation represents a potentially curative treatment for many AML patients. Donor immune cells, namely, T cells and NK cells, can help eliminate residual leukemia cells through the beneficial graft-versus-leukemia (GVL) effect. Nevertheless, malignant cells can still escape allogeneic immune surveillance and lead to disease relapse. Recent studies have provided insights into AML-specific immune evasion mechanisms, many of which are driven by epigenetic changes. This article describes epigenetic regulators as promising therapeutic targets for designing posttransplant maintenance therapies. Therefore, this review aims to summarize AML immune evasion mechanisms with a focus on the allogeneic immune environment. We discuss the roles of epigenetic regulators in driving immune escape and propose targeted strategies for preventing leukemia relapse. We then discuss the diverse immunomodulatory effects of epigenetic inhibitors and their potential to enhance the GVL effect. The current landscape of maintenance therapy trials with epigenetic inhibitors and their clinical prospects is also assessed.

Tolerance induction by liposomes targeting a single CD8 epitope IGRP206-214 in a model of type 1 diabetes is impeded by co-targeting a CD4+ islet epitope.

The autoimmune disease type 1 diabetes is predominantly mediated by CD8+ cytotoxic T-cell destruction of islet beta cells, of which islet-specific glucose-6-phosphatase catalytic subunit-related protein (IGRP)206-214 is a dominant target antigen specificity. Previously, we found that a liposome-based antigen-specific immunotherapy encapsulating the CD4+ T-cell islet epitope 2.5mim together with the nuclear factor-κB inhibitor calcitriol induced regulatory T cells and protected from diabetes in NOD mice. Here we investigated whether the same system delivering IGRP206-214 could induce antigen-specific CD8+ T-cell-targeted immune regulation and delay diabetes. Subcutaneous administration of IGRP206-214 /calcitriol liposomes transiently activated and expanded IGRP-specific T-cell receptor transgenic 8.3 CD8+ T cells. Liposomal co-delivery of calcitriol was required to optimally suppress endogenous IGRP-specific CD8+ T-cell interferon-γ production and cytotoxicity. Concordantly, a short course of IGRP206-214 /calcitriol liposomes delayed diabetes progression and reduced insulitis. However, when IGRP206-214 /calcitriol liposomes were delivered together with 2.5mim /calcitriol liposomes, disease protection was not observed and the regulatory effect of 2.5mim /calcitriol liposomes was abrogated. Thus, tolerogenic liposomes that target either a dominant CD8+ or a CD4+ T-cell islet epitope can delay diabetes progression but combining multiple epitopes does not enhance protection.

The role of Mesothelin signaling in Portal Fibroblasts in the pathogenesis of cholestatic liver fibrosis.

Liver fibrosis develops in response to chronic toxic or cholestatic injury, and is characterized by apoptosis of damaged hepatocytes, development of inflammatory responses, and activation of Collagen Type I producing myofibroblasts that make liver fibrotic. Two major cell types, Hepatic Stellate Cells (HSCs) and Portal Fibroblasts (PFs) are the major source of hepatic myofibroblasts. Hepatotoxic liver injury activates Hepatic Stellate Cells (aHSCs) to become myofibroblasts, while cholestatic liver injury activates both aHSCs and Portal Fibroblasts (aPFs). aPFs comprise the major population of myofibroblasts at the onset of cholestatic injury, while aHSCs are increasingly activated with fibrosis progression. Here we summarize our current understanding of the role of aPFs in the pathogenesis of cholestatic fibrosis, their unique features, and outline the potential mechanism of targeting aPFs in fibrotic liver.

HMGB1 amplifies ILC2-induced type-2 inflammation and airway smooth muscle remodelling.

Type-2 immunity elicits tissue repair and homeostasis, however dysregulated type-2 responses cause aberrant tissue remodelling, as observed in asthma. Severe respiratory viral infections in infancy predispose to later asthma, however, the processes that mediate tissue damage-induced type-2 inflammation and the origins of airway remodelling remain ill-defined. Here, using a preclinical mouse model of viral bronchiolitis, we find that increased epithelial and mesenchymal high-mobility group box 1 (HMGB1) expression is associated with increased numbers of IL-13-producing type-2 innate lymphoid cell (ILC2s) and the expansion of the airway smooth muscle (ASM) layer. Anti-HMGB1 ablated lung ILC2 numbers and ASM growth in vivo, and inhibited ILC2-mediated ASM cell proliferation in a co-culture model. Furthermore, we identified that HMGB1/RAGE (receptor for advanced glycation endproducts) signalling mediates an ILC2-intrinsic IL-13 auto-amplification loop. In summary, therapeutic targeting of the HMGB1/RAGE signalling axis may act as a novel asthma preventative by dampening ILC2-mediated type-2 inflammation and associated ASM remodelling.

Discovery of ethyl ketone-based HDACs 1, 2, and 3 selective inhibitors for HIV latency reactivation.

A novel series of ethyl ketone based HDACs 1, 2, and 3 selective inhibitors have been identified with good enzymatic and cellular activity and high selectivity over HDACs 6 and 8. These inhibitors contain a spirobicyclic group in the amide region. Compound 13 stands out as a lead due to its good potency, high selectivity, and reasonable rat and dog PK. Compounds 33 and 34 show good potency and rat PK profiles as well.

Respiratory Syncytial Virus Infection Promotes Necroptosis and HMGB1 Release by Airway Epithelial Cells.

Rationale: Respiratory syncytial virus (RSV) bronchiolitis causes significant infant mortality. Bronchiolitis is characterized by airway epithelial cell (AEC) death; however, the mode of death remains unknown.Objectives: To determine whether necroptosis contributes to RSV bronchiolitis pathogenesis via HMGB1 (high mobility group box 1) release.Methods: Nasopharyngeal samples were collected from children presenting to the hospital with acute respiratory infection. Primary human AECs and neonatal mice were inoculated with RSV and murine Pneumovirus, respectively. Necroptosis was determined via viability assays and immunohistochemistry for RIPK1 (receptor-interacting protein kinase-1), MLKL (mixed lineage kinase domain-like pseudokinase) protein, and caspase-3. Necroptosis was blocked using pharmacological inhibitors and RIPK1 kinase-dead knockin mice.Measurements and Main Results: HMGB1 levels were elevated in nasopharyngeal samples of children with acute RSV infection. RSV-induced epithelial cell death was associated with increased phosphorylated RIPK1 and phosphorylated MLKL but not active caspase-3 expression. Inhibition of RIPK1 or MLKL attenuated RSV-induced HMGB1 translocation and release, and lowered viral load. MLKL inhibition increased active caspase-3 expression in a caspase-8/9-dependent manner. In susceptible mice, Pneumovirus infection upregulated RIPK1 and MLKL expression in the airway epithelium at 8 to 10 days after infection, coinciding with AEC sloughing, HMGB1 release, and neutrophilic inflammation. Genetic or pharmacological inhibition of RIPK1 or MLKL attenuated these pathologies, lowered viral load, and prevented type 2 inflammation and airway remodeling. Necroptosis inhibition in early life ameliorated asthma progression induced by viral or allergen challenge in later life.Conclusions: Pneumovirus infection induces AEC necroptosis. Inhibition of necroptosis may be a viable strategy to limit the severity of viral bronchiolitis and break its nexus with asthma.

Long-lived regulatory T cells generated during severe bronchiolitis in infancy influence later progression to asthma.

The type-2 inflammatory response that promotes asthma pathophysiology occurs in the absence of sufficient immunoregulation. Impaired regulatory T cell (Treg) function also predisposes to severe viral bronchiolitis in infancy, a major risk factor for asthma. Hence, we hypothesized that long-lived, aberrantly programmed Tregs causally link viral bronchiolitis with later asthma. Here we found that transient plasmacytoid dendritic cell (pDC) depletion during viral infection in early-life, which causes the expansion of aberrant Tregs, predisposes to allergen-induced or virus-induced asthma in later-life, and is associated with altered airway epithelial cell (AEC) responses and the expansion of impaired, long-lived Tregs. Critically, the adoptive transfer of aberrant Tregs (unlike healthy Tregs) to asthma-susceptible mice failed to prevent the development of viral-induced or allergen-induced asthma. Lack of protection was associated with increased airway epithelial cytoplasmic-HMGB1 (high-mobility group box 1), a pro-type-2 inflammatory alarmin, and granulocytic inflammation. Aberrant Tregs expressed lower levels of CD39, an ectonucleotidase that hydrolyzes extracellular ATP, a known inducer of alarmin release. Using cultured mouse AECs, we identify that healthy Tregs suppress allergen-induced HMGB1 translocation whereas this ability is markedly impaired in aberrant Tregs. Thus, defective Treg programming in infancy has durable consequences that underlie the association between bronchiolitis and subsequent asthma.

A randomized trial to assess the immediate impact of acupuncture on quantitative sensory testing, pain, and functional status.

In this randomized clinical trial, we examined whether the effect of true acupuncture can be differentiated from sham acupuncture (pain and functionality) by analyzing quantitative sensory testing (QST) profiles in chronic pain participants. We recruited 254 healthy or chronic back and neck pain participants. Healthy subjects were included to control for a possible effect of acupuncture on baseline QST changes. Study participants received 6 sessions (twice weekly) of true acupuncture, sham acupuncture, or no acupuncture treatment (routine care). Quantitative sensory testing profiles, pain scores, and functionality profile were obtained at baseline (visit 1) and after 3 (visit 4) or 6 sessions (visit 7). A total of 204 participants were analyzed. We found no QST profile changes among 3 groups (P = 0.533 and P = 0.549, likelihood ratio tests) in either healthy or chronic pain participants. In chronic back and neck pain participants, true acupuncture reduced pain (visit 4: difference in mean [DIM] = -0.8, 95% confidence interval [CI]: -1.4 to -0.1, adjusted P = 0.168; visit 7: DIM = -1.0, 95% CI: -1.7 to -0.3, adjusted P = 0.021) and improved functional status including physical functioning (DIM = 14.21, 95% CI: 5.84-22.58, adjusted P = 0.003) and energy/fatigue (DIM = 12.28, 95% CI: 3.46-21.11, adjusted P = 0.021) as compared to routine care. Our results indicate that QST was not helpful to differentiate between true acupuncture and sham acupuncture (primary outcome) in this study, although true acupuncture reduced pain and improved functionality (secondary outcomes) when compared with routine care.