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Osteoarthritis is characterized by enzymatic breakdown of the articular cartilage via the disruption of chondrocyte homeostasis, ultimately resulting in the destruction of the articular surface. Decades of research have highlighted the importance of inflammation in osteoarthritis progression, with inflammatory cytokines shifting resident chondrocytes into a pro-catabolic state. Inflammation can result in poor outcomes for cells implanted for cartilage regeneration. Therefore, a method to promote the growth of new cartilage and protect the implanted cells from the pro-inflammatory cytokines found in the joint space is required. In this study, we fabricate two gel types: polymer network hydrogels composed of chondroitin sulfate and hyaluronic acid, glycosaminoglycans (GAGs) known for their anti-inflammatory and prochondrogenic activity, and interpenetrating networks of GAGs and collagen I. Compared to a collagen-only hydrogel, which does not provide an anti-inflammatory stimulus, chondrocytes in GAG hydrogels result in reduced production of pro-inflammatory cytokines and enzymes as well as preservation of collagen II and aggrecan expression. Overall, GAG-based hydrogels have the potential to promote cartilage regeneration under pro-inflammatory conditions. Further, the data have implications for the use of GAGs to generally support tissue engineering in pro-inflammatory environments.

BackgroundWith the high prevalence of diabetic retinopathy and its significant visual consequences if untreated, timely identification and management of diabetic retinopathy is essential. Teleophthalmology programs have assisted in screening a large number of individuals at risk for vision loss from diabetic retinopathy. Training nonophthalmological readers to assess remote fundus images for diabetic retinopathy may further improve the efficiency of such programs. ObjectiveThis study aimed to evaluate the performance, safety implications, and progress of 2 ophthalmology nurses trained to read and assess diabetic retinopathy fundus images within a hospital diabetic retinopathy telescreening program. MethodsIn this retrospective interobserver study, 2 ophthalmology nurses followed a specific training program within a hospital diabetic retinopathy telescreening program and were trained to assess diabetic retinopathy images at 2 levels of intervention: detection of diabetic retinopathy (level 1) and identification of referable disease (level 2). The reliability of the assessment by level 1−trained readers in 266 patients and of the identification of patients at risk of vision loss from diabetic retinopathy by level 2−trained readers in 559 more patients were measured. The learning curve, sensitivity, and specificity of the readings were evaluated using a group consensus gold standard. ResultsAn almost perfect agreement was measured in identifying the presence of diabetic retinopathy in both level 1 readers (κ=0.86 and 0.80) and in identifying referable diabetic retinopathy by level 2 readers (κ=0.80 and 0.83). At least substantial agreement was measured in the level 2 readers for macular edema (κ=0.79 and 0.88) for all eyes. Good screening threshold sensitivities and specificities were obtained for all level readers, with sensitivities of 90.6% and 96.9% and specificities of 95.1% and 85.1% for level 1 readers (readers A and B) and with sensitivities of 86.8% and 91.2% and specificities of 91.7% and 97.0% for level 2 readers (readers A and B). This performance was achieved immediately after training and remained stable throughout the study. ConclusionsNotwithstanding the small number of trained readers, this study validates the screening performance of level 1 and level 2 diabetic retinopathy readers within this training program, emphasizing practical experience, and allows the establishment of an ongoing assessment clinic. This highlights the importance of supervised, hands-on experience and may help set parameters to further calibrate the training of diabetic retinopathy readers for safe screening programs.

RNA origami is a method for designing RNA nanostructures that can self-assemble through co-transcriptional folding with applications in nanomedicine and synthetic biology. However, to advance the method further, an improved understanding of RNA structural properties and folding principles is required. Here we use cryogenic electron microscopy to study RNA origami sheets and bundles at sub-nanometre resolution revealing structural parameters of kissing-loop and crossover motifs, which are used to improve designs. In RNA bundle designs, we discover a kinetic folding trap that forms during folding and is only released after 10 h. Exploration of the conformational landscape of several RNA designs reveal the flexibility of helices and structural motifs. Finally, sheets and bundles are combined to construct a multidomain satellite shape, which is characterized by individual-particle cryo-electron tomography to reveal the domain flexibility. Together, the study provides a structural basis for future improvements to the design cycle of genetically encoded RNA nanodevices.

Many endothelial complications, whether from surgical or pathological origins, can result in the denudation of the endothelial layer and the exposure of collagen. Exposure of collagen results in the activation of platelets, leading to thrombotic and inflammatory cascades that ultimately result in vessel stenosis. We have previously reported the use of peptide-GAG compounds to target exposed collagen following endothelial injury. In this paper we optimize the spacer sequence of our collagen binding peptide to increase its conjugation to GAG backbones and increase the peptide-GAG collagen binding affinity by increasing peptide C-terminal cationic charge. Furthermore, we demonstrate the use of these molecules to inhibit platelet activation through collagen blocking, as well as their localization to exposed vascular collagen following systemic delivery. Altogether, optimization of peptide sequence and linkage chemistry can allow for increased conjugation and function, having implications for glycoconjugate use in other clinical applications.

Although severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) initially infects the respiratory tract, it also directly or indirectly affects other organs, including the brain. However, little is known about the relative neurotropism of SARS-CoV-2 variants of concern (VOCs), including Omicron (B.1.1.529), which emerged in November 2021 and has remained the dominant pathogenic lineage since then. To address this gap, we examined the relative ability of Omicron, Beta (B.1.351), and Delta (B.1.617.2) to infect the brain in the context of a functional human immune system by using human angiotensin-converting enzyme 2 (hACE2) knock-in triple-immunodeficient NGC mice with or without reconstitution with human CD34+ stem cells. Intranasal inoculation of huCD34+-hACE2-NCG mice with Beta and Delta resulted in productive infection of the nasal cavity, lungs, and brain on day 3 post-infection, but Omicron was surprisingly unique in its failure to infect either the nasal tissue or brain. Moreover, the same infection pattern was observed in hACE2-NCG mice, indicating that antiviral immunity was not responsible for the lack of Omicron neurotropism. In independent experiments, we demonstrate that nasal inoculation with Beta or with D614G, an ancestral SARS-CoV-2 with undetectable replication in huCD34+-hACE2-NCG mice, resulted in a robust response by human innate immune cells, T cells, and B cells, confirming that exposure to SARS-CoV-2, even without detectable infection, is sufficient to induce an antiviral immune response. Collectively, these results suggest that modeling of the neurologic and immunologic sequelae of SARS-CoV-2 infection requires careful selection of the appropriate SARS-CoV-2 strain in the context of a specific mouse model.

We evaluated the association between implementation of state-mandated pulse oximetry screening (POS) and rates of emergency hospitalizations among infants with Critical Congenital Heart Disease (CCHD) and assessed differences in that association across race/ethnicity. We hypothesized that emergency hospitalizations among infants with CCHD decreased after implementation of mandated POS and that the reduction was larger among racial and ethnic minorities compared to non-Hispanic Whites. We utilized statewide inpatient databases from Arizona, California, Kentucky, New Jersey, New York, and Washington State (2010-2014). A difference-in-differences model with negative binomial regression was used. We identified patients with CCHD whose hospitalizations between three days and three months of life were coded as emergency or urgent or occurred through the emergency department. Numbers of emergency hospitalizations aggregated by month and state were used as outcomes. The intervention variable was an implementation of state-mandated POS. Difference in association across race/ethnicity was evaluated with interaction terms between the binary variable indicating the mandatory policy period and each race/ethnicity group. The model was adjusted for state-specific variables, such as percent of female infants and percent of private insurance. We identified 9,147 CCHD emergency hospitalizations. Among non-Hispanic Whites, there was a 22% (Confidence Interval [CI] 6%-36%) decline in CCHD emergency hospitalizations after implementation of mandated POS, on average. This decline was 65% less among non-Hispanic Blacks compared to non-Hispanic Whites. Our study detected an attenuated association with decreased number of emergency hospitalizations among Black compared to White infants. Further research is needed to clarify this disparity.

The tumor microenvironment (TME) plays an essential role in the development, proliferation, and survival of leukemic blasts in acute myeloid leukemia (AML). Within the bone marrow and peripheral blood, various phenotypically and functionally altered cells in the TME provide critical signals to suppress the anti-tumor immune response, allowing tumor cells to evade elimination. Thus, unraveling the complex interplay between AML and its microenvironment may have important clinical implications and are essential to directing the development of novel targeted therapies. This review summarizes recent advancements in our understanding of the AML TME and its ramifications on current immunotherapeutic strategies. We further review the role of natural products in modulating the TME to enhance response to immunotherapy.

The emergence of Zika virus (ZIKV) as a global health threat has highlighted the unmet need for ZIKV-specific vaccines and antiviral treatments. ZIKV infects dendritic cells (DC), which have pivotal functions in activating innate and adaptive antiviral responses; however, the mechanisms by which DC function is subverted to establish ZIKV infection are unclear. Here we develop a genomics profiling method that enables discrete analysis of ZIKV-infected versus neighboring, uninfected primary human DCs to increase the sensitivity and specificity with which ZIKV-modulated pathways can be identified. The results show that ZIKV infection specifically increases the expression of genes enriched for lipid metabolism-related functions. ZIKV infection also increases the recruitment of sterol regulatory element-binding protein (SREBP) transcription factors to lipid gene promoters, while pharmacologic inhibition or genetic silencing of SREBP2 suppresses ZIKV infection of DCs. Our data thus identify SREBP2-activated transcription as a mechanism for promoting ZIKV infection amenable to therapeutic targeting.

Learning Objectives: We wanted to assess whether emergency department (ED) patients presenting with chest pain with a high sensitivity troponin under the 99th percentile drawn at 6 hours or greater after symptom onset could safely be discharged from the ED.Background: High sensitivity troponin (hsT) assays have become widespread for emergency department (ED) evaluation of acute chest pain. Several studies have demonstrated safety of a “rapid rule-out” strategy, evaluating initial hsT with repeat testing at 1-2 hours. A small number of patients can be discharged using this strategy while the most patients have a detectable hsT level and require a prolonged workup.Objective: We assessed if a hsT under the 99th percentile drawn at 6 hours or greater from symptom onset could safely rule out patients.Methods: We conducted a multicenter retrospective study examining ED patients with chest pain who did not meet rapid-rule out criteria and were admitted for further evaluation. Among these admitted patients, we assessed the rate of clinically relevant acute cardiac events (CRACE) and NSTEMI in patients with hsT less than 99th percentile (34 ng/mL in females, 53 ng/mL in males) obtained after at least 6 hours of chest pain. CRACE was defined as death, cardiac arrest, STEMI, or life-threatening arrhythmia. A manual chart review was conducted with 10% of randomly selected charts to estimate the number of patients admitted with nonischemic ECG and no other compelling reason for admission (unstable vitals or additional diagnoses).Results: Out of 1189 patients admitted, we found 30 CRACE, all of which occurred in patients admitted for another compelling reason or ischemic ECG. 36 patients had an NSTEMI, of which 33 were identified with hsT above 99th percentile within 6 hours of chest pain onset. This left 0 CRACE and 3 NSTEMI among the 430 patients with a negative hsT at 6 hours and nonischemic ECG and no other compelling reason for admission.Conclusion: Patients who have hsT values under the 99th percentile after 6 hours of chest pain have a low rate of CRACE and NSTEMI. Future prospective studies to evaluate the safety of outpatient management are warranted.

Glycosaminoglycans (GAGs), such as hyaluronic acid (HA) and chondroitin sulfate (CS), have seen widespread adoption as components of tissue engineering scaffolds because of their potent bioactive properties and ease of chemical modification. However, modification of the biopolymers will impair biological recognition of the GAG and reduce the bioactive properties of the material. In this work, we studied how the degree of thiolation of HA and CS, along with other key hydrogel design parameters, affected the physical and bioactive properties of the bulk hydrogel. Although properties, such as the HA molecular weight, did not have a major effect, increasing the degree of thiolation of both HA and CS decreased their biorecognition in experimental analogues for cell/matrix remodeling and binding. Furthermore, combining HA and CS into dual polymer network hydrogels also modulated the physical and bioactive properties, as seen with differences in gel stiffness, degradation rate, and encapsulated cell viability.

Hydrogels have been widely investigated in biomedical fields due to their similar physical and biochemical properties to the extracellular matrix (ECM). Collagen and hyaluronic acid (HA) are the main components of the ECM in many tissues. As a result, hydrogels prepared from collagen and HA hold inherent advantages in mimicking the structure and function of the native ECM. Numerous studies have focused on the development of collagen and HA hydrogels and their biomedical applications. In this extensive review, we provide a summary and analysis of the sources, features, and modifications of collagen and HA. Specifically, we highlight the fabrication, properties, and potential biomedical applications as well as promising commercialization of hydrogels based on these two natural polymers.

The majority of fracture research has been conducted using long bone fracture models, with significantly less research into the mechanisms driving craniofacial repair. However, craniofacial bones differ from long bones in both their developmental mechanism and embryonic origin. Thus, it is possible that their healing mechanisms could differ. In this study we utilize stabilized and unstabilized mandible fracture models to investigate the pathways regulating repair. Whereas fully stable trephine defects in the ramus form bone directly, mechanical motion within a transverse fracture across the same anatomical location promoted robust cartilage formation before boney remodeling. Literature investigating long bone fractures show chondrocytes are a direct precursor of osteoblasts during endochondral repair. Lineage tracing with Aggrecan-CreERT2 ::Ai9 tdTomato mice demonstrated that mandibular callus chondrocytes also directly contribute to the formation of new bone. Furthermore, immunohistochemistry revealed that chondrocytes located at the chondro-osseous junction expressed Sox2, suggesting that plasticity of these chondrocytes may facilitate this chondrocyte-to-osteoblast transformation. Based on the direct role chondrocytes play in bone repair, we tested the efficacy of cartilage grafts in healing critical-sized mandibular defects. Whereas empty defects remained unbridged and filled with fibrous tissue, cartilage engraftment produced bony-bridging and robust marrow cavity formation, indicating healthy vascularization of the newly formed bone. Engrafted cartilage directly contributed to new bone formation since a significant portion of the newly formed bone was graft/donor-derived. Taken together these data demonstrate the important role of chondrocyte-to-osteoblast transformation during mandibular endochondral repair and the therapeutic promise of using cartilage as a tissue graft to heal craniofacial defects.

PurposeAlthough commercial optical coherence tomography angiography (OCTA) machines quantitate retinal vascular density (VD) by dividing the vasculature into superficial and deep capillary plexus (SCP, DCP), histology reveals three distinct plexus layers. This study tested the hypothesis that the VD measurement of three distinct retinal plexus layers obtained using custom segmentation has high repeatability comparable to that of automatically segmented SCP and DCP layers.Materials and methodsForty-four participants (86 eyes) were enrolled - 54 eyes with retinal vasculopathy and 25 eyes with macular edema. Macular OCTA images (3x3 mm and 6x6 mm) were obtained twice within 30 minutes by the same personnel using the same instrument (AngioVue, Optovue, version 2018.0.0.18). The intraclass correlation coefficient (ICC) was calculated to access repeatability.ResultsThe repeatability of VD for SCP and DCP was good-to-moderate (ICC=0.65-0.85) and minimally affected by image quality, retinal vasculopathy, or macular edema. The repeatability of the VD of the custom-segmented intermediate and deep plexus layers (cICP and cDCP) was poor/moderate (ICC=0.40-0.74) but better in the subset without macular edema using 3x3 mm scans with good images quality (ICC=0.58-0.93). Repeatability of cICP and cDCP VD measurement for 6x6 mm scans was poor (ICC≤0.5) in eyes with retinal vasculopathy and/or macular edema.ConclusionAlthough repeatability of the VD measurement is high for the automatically segmented SCP and DCP, repeatability of VD is poor for the cICP and cDCP using larger scans in eyes with retinal vasculopathy and/or macular edema.

Background: Numerous studies in the clinical literature have explored the link between nutrition and skin physiology. However, it is unclear whether patients visit their dermatologists with knowledge of these studies, and unknown where they obtain their skin health information. We characterized patient perceptions surrounding nutrition and skin, including what patients identified as aggravating and alleviating foods and their information sources. Methods: We administered a questionnaire to 409 participants attending University of California (UC) Davis Dermatology and Pacific Skin Institute in Sacramento. This survey assessed their perception on the influence of nutrition. We stratified responses by diseases. Results: Of the 409 respondents, 83% believed that nutrition affects skin health. Respondents with healthy skin were not more likely to agree than those with skin conditions in general (P=0.34). Those with skin conditions also more likely received their information from reputable sources, defined as physicians and scientific journals (P=0.02). Additionally, respondents who disagreed were more likely informed by reputable sources (P=0.002), but when online blogs were included as reputable, this relationship was less significant (P=0.046). Conclusions: As online resources become more accessible, it is important for providers to know about changing patient perspectives. Our findings may help improve how dermatologists counsel patients about nutrition.