The role of cannabinoid receptor 2 in bone remodeling during orthodontic tooth movement

BACKGROUND

The purpose of this study is to explore the effects of CB2 on bone regulation during orthodontic tooth movement.

METHODS

Thirty male mice were allocated into 2 groups (n = 15 in each group): wild type (WT) group and CB2 knockout (CB2-/-) group. Orthodontic tooth movement (OTM) was induced by applying a nickel-titanium coil spring between the maxillary first molar and the central incisors. There are three subgroups within the WT groups (0, 7 and 14 days) and the CB2-/- groups (0, 7 and 14 days). 0-day groups without force application. Tooth displacement, alveolar bone mass and alveolar bone volume were assessed by micro-CT on 0, 7 and 14 days, and the number of osteoclasts was quantified by tartrate-resistant acid phosphatase (TRAP) staining. Moreover, the expression levels of RANKL and OPG in the compression area were measured histomorphometrically.

RESULTS

The WT group exhibited the typical pattern of OTM, characterized by narrowed periodontal space and bone resorption on the compression area. In contrast, the accelerated tooth displacement, increased osteoclast number (P < 0.0001) and bone resorption on the compression area in CB2-/- group. Additionally, the expression of RANKL was significantly upregulated, while OPG showed low levels in the compression area of the CB2 - / - group (P < 0.0001).

CONCLUSIONS

CB2 modulated OTM and bone remodeling through regulating osteoclast activity and RANKL/OPG balance.

[Short-term outcomes of modified load-sharing rip-stop repair compared with suture-bridge repair for large rotator cuff tears]

Objective: To examine the short-term outcomes of modified load-sharing rip-stop repair (mLSRS) and suture-bridge repair (SB) for large rotator cuff tear. Methods: The clinical data of patients who underwent shoulder arthroscopy for large rotator cuff repair at Department of Orthopedic, China Academy of Chinese Medical Sciences Wang Jing Hospital from January 2017 to December 2018 were collected. Totally 111 patients (39 in mLSRS group and 72 in SB group) were included in the study. There were 45 males and 66 females, aged (58.0±6.9)years (range: 40 to 72 years).A total of 39 pairs of patients were successfully matched by propensity score matching. The pain of shoulder joint was assessed by visual analogy score (VAS) , the shoulder function was assessed by Constant-Murley score, the abduction strength of bilateral shoulder joint was assessed by 90˚ force assessment method of upper limb on the plane of scapula, and the healing of rotator cuff on the operative side was assessed by sugaya ultrasonic classification standard. The difference of short-term outcome between the two groups were compared using t test, χ(2) test, Mann-Whitney U test, repeated measures design anova and multivariate analysis of variance. Results: At the 4th week after surgery, the VAS of mLSRS group was significantly lower than SB group(1 (2) vs. 2 (2) , F=5.32, P=0.02). One year after surgery, Constant-Murley score of two groups were significantly higher than those before surgery, but there was no significant difference between two groups(89.1±5.7 vs. 87.6±7.3, t=1.00, P=0.32). Abductor strength of affected limbs were lower than that of the opposite side, but there were no statistically significant differences between two groups(4.28±1.61 vs. 4.54±1.64, t=-0.70, P=0.49). According to the Sugaya classification, 32 cases in mLSRS group were healed while 7 cases were not healed,30 cases in SB group were healed while 9 cases were not healed(χ(2)=0.32, P=0.58). Conclusion: The use of mLSRS fixation construct on large rotator cuff tear can reduce pain and the short-term outcome is reliable.

[Phylogenetic analysis of Echinococcus granulosus genotypes based on the GenBank database]

OBJECTIVE

To analyze the sequences of the cytochrome C oxidase subunit I (Cox1) gene of various Echinococcus granulosus genotypes that are currently recorded in the GenBank database, so as to investigate the genetic variation and differentiation of the E. granulosus genotypes across the world.

METHODS

The sequences of the Cox1 gene of various E. granulosus genotypes that are currently recorded in the GenBank database were collected, and the same sequences of the Cox1 gene identified from a region were excluded. The mutation sites among the Cox1 gene sequences were identified and a phylogenetic tree was created based on the Cox1 gene.

RESULTS

Transversion mutation was the predominant type of mutation in the Cox1 gene of E. granulosus. The same Cox1 gene sequence was found in E. granulosus G1, G6 and G7 genotypes isolated from various geographical locations across the world, with the corresponding GenBank accession numbers of KY766891, MH300971 and MH301007, respectively. Phylogenetic analysis revealed that E. granulosus G10 genotype had a remarkable geographical aggregation.

CONCLUSIONS

E. granulosus G1, G6 and G7 genotypes have primitive Cox1 gene sequences. There is a geographical aggregation of the E. granulosus G10 genotype in the phylogenetic tree, which has a tendency towards reproductive isolation.

Self-powered diamond ultraviolet photodetector with a transparent Ag nanowire electrode

A novel diamond UV photodetector with a transparent Ag nanowire (NW) electrode was fabricated. A transparent Ag NW network was spin-coated on single crystalline diamond to form a Schottky contact, which had a barrier height of about 1.37 eV obtained by XPS measurements. Meanwhile, multilayered metals of Au/Pt/Ti were evaporated on the diamond sample to form ohmic contacts. Compared to a Au/Pt/Ti-Au/Pt/Ti diamond photodetector, the Au/Pt/Ti-Ag NW diamond photodetector exhibited relatively high responsivity under 220 nm (18 mA W^-1), high linear dynamic range (41 dB), and short response time (0.12 s for rise time, 0.56 s for decay time). In particular, the Au/Pt/Ti-Ag NW diamond photodetector displayed high photocurrent of about 200 pA at zero-bias, indicating its potential for creating self-powered devices.

Broadband nonlinear optical response in multi-layer black phosphorus: an emerging infrared and mid-infrared optical material

Black phosphorous (BP), the most thermodynamically stable allotrope of phosphorus, is a high-mobility layered semiconductor with direct band-gap determined by the number of layers from 0.3 eV (bulk) to 2.0 eV (single layer). Therefore, BP is considered as a natural candidate for broadband optical applications, particularly in the infrared (IR) and mid-IR part of the spectrum. The strong light-matter interaction, narrow direct band-gap, and wide range of tunable optical response make BP as a promising nonlinear optical material, particularly with great potentials for infrared and mid-infrared opto-electronics. Herein, we experimentally verified its broadband and enhanced saturable absorption of multi-layer BP (with a thickness of ~10 nm) by wide-band Z-scan measurement technique, and anticipated that multi-layer BPs could be developed as another new type of two-dimensional saturable absorber with operation bandwidth ranging from the visible (400 nm) towards mid-IR (at least 1930 nm). Our results might suggest that ultra-thin multi-layer BP films could be potentially developed as broadband ultra-fast photonics devices, such as passive Q-switcher, mode-locker, optical switcher etc.

Physiological integration enhanced the tolerance of Cynodon dactylon to flooding

Many flooding-tolerant species are clonal plants; however, the effects of physiological integration on plant responses to flooding have received limited attention. We hypothesise that flooding can trigger changes in metabolism of carbohydrates and ROS (reactive oxygen species) in clonal plants, and that physiological integration can ameliorate the adverse effects of stress, subsequently restoring the growth of flooded ramets. In the present study, we conducted a factorial experiment combining flooding to apical ramets and stolon severing (preventing physiological integration) between apical and basal ramets of Cynodon dactylon, which is a stoloniferous perennial grass with considerable flooding tolerance. Flooding-induced responses including decreased root biomass, accumulation of soluble sugar and starch, as well as increased activity of superoxide dismutase (SOD) and ascorbate peroxidase (APX) in apical ramets. Physiological integration relieved growth inhibition, carbohydrate accumulation and induction of antioxidant enzyme activity in stressed ramets, as expected, without any observable cost in unstressed ramets. We speculate that relief of flooding stress in clonal plants may rely on oxidising power and electron acceptors transferred between ramets through physiological integration.