H3K27ac is well recognized as a marker for active enhancers and a great indicator of enhancer activity. However, its functional impact on transcription has not been characterized. By substituting lysine 27 in histone variant H3.3 with arginine in mouse embryonic stem cells, we diminish the vast majority of H3K27ac at enhancers. However, the transcriptome is largely undisturbed in these mutant cells, likely because the other enhancer features remain largely unchanged, including chromatin accessibility, H3K4me1, and histone acetylation at other lysine residues. Our results clearly reveal that H3K27ac alone is not capable of functionally determining enhancer activity.

Bivalent genes are ready for activation upon the arrival of developmental cues. Here, we report that BEND3 is a CpG island (CGI)–binding protein that is enriched at regulatory elements. The cocrystal structure of BEND3 in complex with its target DNA reveals the structural basis for its DNA methylation–sensitive binding property. Mouse embryos ablated of Bend3 died at the pregastrulation stage. Bend3 null embryonic stem cells (ESCs) exhibited severe defects in differentiation, during which hundreds of CGI-containing bivalent genes were prematurely activated. BEND3 is required for the stable association of polycomb repressive complex 2 (PRC2) at bivalent genes that are highly occupied by BEND3, which suggests a reining function of BEND3 in maintaining high levels of H3K27me3 at these bivalent genes in ESCs to prevent their premature activation in the forthcoming developmental stage.

Chromatin inheritance entails de novo nucleosome assembly after DNA replication by chromatin assembly factor-1 (CAF-1). Yet direct knowledge about CAF-1’s histone binding mode and nucleosome assembly process is lacking. In this work, we report the crystal structure of human CAF-1 in the absence of histones and the cryo–electron microscopy structure of CAF-1 in complex with histones H3 and H4. One histone H3-H4 heterodimer is bound by one CAF-1 complex mainly through the p60 subunit and the acidic domain of the p150 subunit. We also observed a dimeric CAF-1–H3-H4 supercomplex in which two H3-H4 heterodimers are poised for tetramer assembly and discovered that CAF-1 facilitates right-handed DNA wrapping of H3-H4 tetramers. These findings signify the involvement of DNA in H3-H4 tetramer formation and suggest a right-handed nucleosome precursor in chromatin replication.

Transplant arteriosclerosis is a leading cause of late allograft loss. Medial smooth muscle cell (SMC) apoptosis is considered to be an important event in transplant arteriosclerosis. However, the precise contribution of medial SMC apoptosis to transplant arteriosclerosis and the underlying mechanisms remain unclear. We transferred wild‐type p53 to induce apoptosis of cultured SMCs. We found that apoptosis induces the production of SDF‐1α from apoptotic and neighboring viable cells, resulting in increased SDF‐1α in the culture media. Conditioned media from Ltv‐p53‐transferred SMCs activated PI3K/Akt/mTOR and MAPK/Erk signaling in a SDF‐1α‐dependent manner and thereby promoted mesenchymal stem cell (MSC) migration and proliferation. In a rat aorta transplantation model, lentivirus‐mediated BclxL transfer selectively inhibits medial SMC apoptosis in aortic allografts, resulting in a remarkable decrease of SDF‐1α both in allograft media and in blood plasma, associated with diminished recruitment of CD90⁺CD105⁺ double‐positive cells and impaired neointimal formation. Systemic administration of rapamycin or PD98059 also attenuated MSC recruitment and neointimal formation in the aortic allografts. These results suggest that medial SMC apoptosis is critical for the development of transplant arteriosclerosis through inducing SDF‐1α production and that MSC recruitment represents a major component of vascular remodeling, constituting a relevant target and mechanism for therapeutic interventions.

Objective: The aim of this prospective randomized double-blind study is to evaluate whether oral dexmedetomidine (DEX) premedication could increase sedation in order to reduce preoperative anxiety and inhibit stress response during general anesthesia tracheal intubation. Materials: A total of 100 ASA I and II adult patients undergoing elective neurosurgery were randomly divided into the control group (C group, n = 50) and the oral DEX premedication (DEX group, n = 50). Patients were administrated 4 μg/kg dexmedetomidine orally pre-anesthesia 120 min. Hemodynamic variables were monitored and recorded from premedication to 10 min after tracheal intubation. The primary outcome, the sedation level of all participants, was evaluated by Richmond Agitation Sedation Scale (RASS), and Numerical Rating Scale was to measure their intensity of thirst and satisfaction of patients’ family members. During general anesthesia induction, the total dosage of induction anesthetics and complications relative to anesthesia induction were recorded. After tracheal intubation, blood sample was drain from radial atrial line to measure levels of adrenocorticotropic hormone (ACTH) and cortisol. Results: RASS scores at 60 min after premedication and on arrival in the operating room were significantly reduced in the DEX group (P < 0.001). Oral DEX premedication not only increased the intensity of thirst but also the satisfaction of their family members (P < 0.001). The cortisol level after tracheal intubation was deduced by oral DEX premedication (P < 0.05). Oral DEX premedication reduced heart rate (HR) and mean arterial pressure (MAP) on arrival in the operating room, and HR when tracheal intubation (P < 0.05). During the whole process of anesthesia induction, although the lowest MAP in two groups were not significantly different, the lowest HR was significantly lower in the DEX group (P < 0.05). Oral DEX premedication might reduce HR from premedication to 10 min after tracheal intubation. However MAP was reduced just from premedication to on arrival in the operating room. Total induction dosages of propofol, midazolam, sulfentanil and rocuronium were similar in two groups (P > 0.05), as well as the complications relative to anesthesia induction and cases of rescue dopamine therapy were similar (P > 0.05). Conclusion: Oral DEX 4 μg/kg premedication was an efficient intervention to increase preoperative sedation and reduce stress reaction induced by general anesthesia tracheal intubation, but also it was with the stable hemodynamic during the process of general anesthesia tracheal intubation, and improved the satisfaction of patients’ family members. In this study, the sparing-anesthetic effect of 4 μg/kg DEX oral premedication was not significant, and this would be needed to study in future. Trial registration: This trail was registered at Chinese Clinical Trial Registry (https://www.chictr.org.cn, Jie Gao) on 15/04/2021, registration number was ChiCTR2100045458.

Objective: Ciprofol is a novel anesthetic agent, its efficacy and safety had been verified and its clinical implementation has been expanded. However, the knowledge about ciprofol in children is meager. The aim of study is to evaluate the safety and effectiveness of ciprofol in general anesthesia in children undergoing adenoidectomy and adenotonsillectomy, compared with propofol. Materials: We retrospectively analyzed data of children who underwent adenoidectomy or adenotonsillectomy with general anesthesia from June to August 2023 to evaluate the safety and effectiveness of ciprofol. The primary outcomes included hemodynamic changes during induction and postoperative complications in post-anesthesia care unit. The secondary outcomes were extubation time, pediatric anesthesia emergence delirium (PAED) score. Meanwhile, subgroup analysis was performed based on age. Results: 301 children met the inclusion criteria, 157 received ciprofol induction and 144 received propofol. Patient demographics and operation-related information were similar in the two groups. However, the dosage of dexmedetomidine in the propofol group was significantly higher than that of the ciprofol group (p=0.001). The trends of hemodynamic shift during induction and intubation were the same in the two groups. The PAED scores on post-extubation 10min and 20min were significantly reduced in the ciprofol group (p< 0.001 and p=0.046). Moreover, in the ≤ 72 months and the > 72 months subgroups, the scores were also significantly lower in the ciprofol group on post-extubation 10min. With the score of > 10, the incidence of emergence delirium of the ciprofol group was significantly lower on post-extubation 10min and 20min in the population and the ≤ 72 months subgroups (p=0.03 and p=0.02). There were no obvious postoperative complications in both groups. Conclusion: Ciprofol exhibited advantageous characteristics in the induction of children, such as stable hemodynamics, a relatively lower incidence of postoperative delirium without apparent post-anesthesia complications. Ciprofol may emerge as a novel option for general anesthesia in pediatric patients.