Injectable Double-Network Hydrogel-Based Three-Dimensional Cell Culture Systems for Regenerating Dental Pulp.

The regeneration of dental pulp tissue is very important, but difficult, in dentistry. The biocompatibility, water content, and viscoelastic properties of pulp-like tissue must be optimized to achieve the efficient transfer of metabolites and nutrients, a suitable degradation rate, distribution of encapsulated cells, injectability, and gelation in situ under physiological conditions. As promising materials for pulp regeneration, hydrogel scaffolds have been produced to simulate the extracellular matrix and transmit signaling molecules. It is imperative to develop hydrogels to effectively regenerate pulp tissue for clinical application. Here, two injectable double-network (DN) hydrogel-based three-dimensional (3D) cell culture systems were developed for regenerating dental pulp. The microstructure, mechanical property, rheology property, and degradation behavior of the injectable DN glycol chitosan-based hydrogels in a simulated root canal model were characterized and compared to a single-network (SN) glycol chitosan-based hydrogel. Human dental pulp stem cells (hDPSCs) were then encapsulated into the GC-based hydrogels for the regeneration of pulp tissue, and the biological performance was investigated both in vitro and in vivo. The results showed that the DN hydrogels had ideal injectability under physiological conditions due to the dynamic nature of the crosslinks. Besides, the DN hydrogels exhibited better mechanical properties and longer degradation duration than the corresponding SN hydrogel. As a 3D cell culture system, the characteristics of the DN hydrogel facilitated odontogenic differentiation and mineralization of hDPSCs in vitro. Further in vivo analysis confirmed that the chemical composition, matrix stiffness, and degradation rate of the DN hydrogel matched those of pulp-like fibrous connective tissue, which might be related to Smad3 activation. These findings demonstrate that DN glycol chitosan-based hydrogels are suitable for the regeneration of pulp tissue.

Orrella daihaiensis sp. nov., a bacterium isolated from Daihai Lake in Inner Mongolia.

A novel aerobic, Gram-staining-negative, non-motile, short-rod-shaped strain, designated f23T, was obtained from Daihai Lake, Inner Mongolia, Republic of China. 16S rRNA gene sequences analysis showed that f23T belongs to the genus Orrella and is most closely related to Orrella marina H-Z20T with 98.35% sequence similarity. The strain was oxidase positive, catalase positive and had well growth at pH 6.5-8.5, at temperature 28-40 °C and at 0-4.5% (w/v) NaCl. Colonies incubated at 37 °C on marine 2216 agar for 3 days were white, smooth, transparent, circular and less than 1.0 mm in diameter. The total genome size of f23T was 2,803,849 bp with a G + C content of 52.79%. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between strain f23T and O. marina H-Z20T were 69.62% and 20.5%, which both below the species delineation threshold. Chemotaxonomic analysis showed that C16:0, cyclo-C17:0, C18:0, Sum Feature 3 (C16:1ω7c and/or C16:1ω6c) and Sum Feature 8 (C18:1ω6c and C18:1ω7c) as the major fatty acids, ubiquinone-8 as the major isoprenoid quinone, phosphatidylethanolamine as the major cellular polar lipids. Based on the polyphasic analysis, f23T represents a novel species within the genus Orrella, for which the name Orrella daihaiensis sp. nov. is proposed. The type strain is f23T (= CGMCC 1.18761 T = KCTC 82425 T).

[Determination Methods of 2019 Novel Coronavirus (SARS-CoV-2)].

This study summarized the determination methods and principles of 2019 novel coronavirus(severe acute respiratory syndrome coronavirus 2,SARS-CoV-2). The advantages and limitations of several methods was compared, which can provide a basis for the selection of 2019 novel coronavirus clinical diagnosis methods.

An injectable double-network hydrogel for the co-culture of vascular endothelial cells and bone marrow mesenchymal stem cells for simultaneously enhancing vascularization and osteogenesis.

The achievement of rapid vascularization in large implanted constructs is a major challenge in the field of bone tissue engineering. Although co-culture of bone-forming cells and vascular endothelial cells (VECs) has been expected to be a way of promoting vascularization during bone formation with a scaffold, there is a lack of detailed knowledge about the direct interactions between two types of stem cells in a three-dimensional (3D) extracellular matrix (ECM). Herein, we report on the use of an injectable cytocompatible double-network (DN) hydrogel to encapsulate, co-culture and subsequently stimulate the angiogenic/osteogenic differentiation of VECs and the human bone marrow mesenchymal stem cells (BM-MSCs), which demonstrates that the direct co-cultured system enables simultaneous enhancement of vascularization and osteogenesis by providing 3D cell-cell communication. Besides, the improved mechanical properties and the injectability of the DN hydrogel allow the delivery, long-time implantation, proliferation and differentiation of stem cells in vivo. Therefore, this study could provide a niche-like native ECM for stem cell survival and the regulation of the differentiation of multiple cell lines which will benefit bone repair.

Structure and function of human Naa60 (NatF), a Golgi-localized bi-functional acetyltransferase.

N-terminal acetylation (Nt-acetylation), carried out by N-terminal acetyltransferases (NATs), is a conserved and primary modification of nascent peptide chains. Naa60 (also named NatF) is a recently identified NAT found only in multicellular eukaryotes. This protein was shown to locate on the Golgi apparatus and mainly catalyze the Nt-acetylation of transmembrane proteins, and it also harbors lysine N(ε)-acetyltransferase (KAT) activity to catalyze the acetylation of lysine ε-amine. Here, we report the crystal structures of human Naa60 (hNaa60) in complex with Acetyl-Coenzyme A (Ac-CoA) or Coenzyme A (CoA). The hNaa60 protein contains an amphipathic helix following its GNAT domain that may contribute to Golgi localization of hNaa60, and the ß7-ß8 hairpin adopted different conformations in the hNaa60(1-242) and hNaa60(1-199) crystal structures. Remarkably, we found that the side-chain of Phe 34 can influence the position of the coenzyme, indicating a new regulatory mechanism involving enzyme, co-factor and substrates interactions. Moreover, structural comparison and biochemical studies indicated that Tyr 97 and His 138 are key residues for catalytic reaction and that a non-conserved ß3-ß4 long loop participates in the regulation of hNaa60 activity.

[Influence of auricular point sticking on incidence of nausea and vomiting and analgesia effect after gynecological laparoscopy].

OBJECTIVE: To observe the influence of auricular point sticking on incidence of nausea and vomiting and analgesia effect after gynecological laparoscopy, and provide evidence for clinical application of auricular point sticking. METHODS: One hundred and twenty cases of selective gynecological laparoscopy under general anesthesia were randomly divided into an auricular point sticking group and a placebo group, 60 cases in each group. In the auricular point sticking group, the auricular point sticking with vaccaria seeds was applied at Shenmen (TF 4), Wei (CO 4) and Jiaogan (AH 6a) before the operation and 1, 5, 9, 23 h after the operation, which were pressed 5 min each point each time. The two ears were proceeded at the same time. In the placebo group, the same point selection, sticking paste was used as the auricular point sticking group, but no sticking or pressing with vaccaria seeds was adopted. The incidence of nausea and vomiting, the usage rate of tropisetron and morphine within 24 hours of the operation, as well as the score of visual analogue scale (VAS) and other adverse reactions at 2, 6, 10, 24 h after the operation were observed respectively. RESULTS: Compared with the placebo group, the incidence of nausea and vomiting [31.7% (19/60), 16.7% (10/60) vs 58.3% (35/60), 35.0% (21/60)], the usage rate of tropisetron [21.7% (13/60) vs 48.3% (29/60)] and morphine [18.3% (11/60) vs 38.3% (23/60)], the VAS scores at all different time points in the auricular point sticking group were all decreased (all P < 0.05), and no adverse reaction was observed. CONCLUSION: The auricular point sticking could significantly decrease the incidence of nausea and vomiting in patients of gynecological laparoscopy and has positive analgesic effect.

Chemical and structural changes in preserved white egg during pickled by vacuum technology.

The aim of the present study was to investigate the chemical and structural changes in preserved white egg during pickled by vacuum technology. In order to evaluate the changes of preserved egg white during its salted period, sulfhydryl group, disulfide bond contents, and surface hydrophobicity were measured. Fourier transformation infrared spectroscopy and circular dichroism analysis were performed by considering changes of the secondary structural elements, the protein components of egg white was also studied in more detail by electrophoresis. Results showed that the sulfhydryl group and surface hydrophobicity were increased with increasing salting time, whereas a decrease in the disulfide bond contents was observed. Regarding the secondary structure analysis, a decrease in α-helices and ß-turns were accompanied by increases in ß-sheets and random coils, which indicating a decrease in non-random structure while ever increasing of unordered structure. Electrophoresis shows no significant differences in protein patterns among fresh egg white and samples salting for up to 4 days. Disappearance of most protein was at the 5th day. Single band of ovalbumin can be readily observed from the 6th day to the ripening period finished. Our findings reveal that high pH could induce duck egg white protein aggregation when salting eggs in strong alkaline solution for a long time.