BACKGROUND:Socket-shield technique can effectively maintain labial soft and hard tissues,but the incidence of postoperative complications such as exposure and displacement of root shield is relatively high.It is speculated that the root shield may be exposed and displaced due to excessive load after long-term function of dental implants. OBJECTIVE:Through three-dimensional finite element analysis,we aim to study the influence of varying root shield thicknesses on the stress distribution,equivalent stress peaks,and displacement in the root shield,periodontal ligaments,implant,and surrounding alveolar bone under normal occlusal loading.We also attempt to analyze the correlation between the thickness of the root shield and occurrence of mechanical events such as root shield exposure,displacement,and fracture. METHODS:Cone-beam CT data of a patient who met the indication standard of socket-shield technique for maxillary central incisor were retrieved from database.Reverse engineering techniques were used to build models of the maxillary bone and root shield,while forward engineering was used to create models for the implant components based on their parameters.Models depicting various root shield thicknesses(0.5,1.0,1.5,and 2.0 mm)were created using Solidworks 2022 software.ANSYS Workbench 2021 software was then used to simulate and analyze the effects of varying root shield thicknesses on stress distribution,equivalent stress peaks,and displacement of the root shields,periodontal ligaments,implants,and surrounding alveolar bone under normal occlusion. RESULTS AND CONCLUSION:(1)In all root shield models,the stress was concentrated on the palatal cervical side,both sides of the edges and the lower edge of the labial side.As the thickness of the root shield increased,the equivalent stress peak and displacement showed a decreasing trend.The 0.5 mm thickness model produced a stress concentration of 176.20 MPa,which exceeded the yield strength(150 MPa)of tooth tissue.(2)The periodontal ligament stress in each group was concentrated in the neck margin and upper region.With the increase of root shield thickness,the equivalent stress peak and displacement of periodontal ligament showed a decreasing trend.(3)Implant stress in all models was concentrated in the neck of the implant and the joint of the implant-repair abutment,and the labial side was more concentrated than the palatal side.With the increase of root shield thickness,the equivalent stress peak of the implant in the model showed an increasing trend.(4)In each group of models,stress of cortical bone concentrated around the neck of the implant and the periphery of the root shield,and the labial side was more concentrated than the palatal side.With the increase of the thickness of the root shield,the equivalent stress peak around the root shield decreased;the peak value of the equivalent stress of the bone around the neck of the implant showed an increasing trend.In the model,the stress of cancellous bone was mainly concentrated around the neck of the lip of the implant,the top of the thread,the root tip and the lower margin of the root shield,and the labial side was more concentrated than the palatal side.With the increase of the thickness of the root shield,the peak value of the equivalent stress of the bone around the root shield in the model showed a decreasing trend.The minimum principal stress of cortical bone in each group of models was concentrated around the neck of the implant,exhibiting a fan-shaped distribution.As the thickness of the root shield increased,the minimum principal stress of cortical bone showed an increasing trend.(5)These results indicate that different thicknesses of the root shield have different biomechanical effects.The root shield with a thickness of 0.5 mm is easy to fracture.For patients with sufficient bone width,the root shield with a thickness of 2.0 mm is an option to reduce the risk of complications such as root shield exposure,fracture,and displacement.Meanwhile,it should be taken into account to protect the periodontal ligament in the preparation process,and rounding treatments ought to be carried out on both sides and the lower edge of the root shield.

In this paper, a preliminary stress/strain analysis of the design structure of a nickel-titanium alloy patent foramen ovale occluder is conducted with the finite element simulation analysis method. In the analysis, solid structure modeling is carried out on three different specifications of domestic patent foramen ovale occluders. Referring to the test method of fatigue performance in inspection standard YY/T 1553-2017, an initial installation deformation is applied to the model, and then the fatigue displacement of 2 mm is applied to the sample to make the model fatigue deformation. The fatigue safety factors of each type of occluder are obtained by strain simulation analysis. The results indicate that the minimum fatigue safety factors of the three specifications of domestic patent foramen ovale occluders are 2.09, 2.35 and 2.06 respectively, which all meet the design of fatigue safety factor greater than 1. Among them, 1818 and 3030 specifications of patent foramen ovale occluders have close values in minimum fatigue safety factors, and both are lower than that of 1825 model. Therefore, it is recommended to carry out physical fatigue tests on both 1818 and 3030 specifications to further verify the fatigue performance of the products.
Finite Element Analysis ; Titanium ; Nickel ; Alloys ; Foramen Ovale, Patent ; Materials Testing ; Septal Occluder Device ; Stress, Mechanical

Ischemic stroke (IS) is a globally life-threatening disease. Presently, few therapeutic medicines are available for treating IS, and rt-PA is the only drug approved by the US Food and Drug Administration (FDA) in the US. In fact, many agents showing excellent neuroprotection but no blood flow-improving activity in animals have not achieved ideal clinical efficacy, while thrombolytic drugs only improving blood flow without neuroprotection have limited their wider application. To address these challenges and meet the huge unmet clinical need, we have designed and identified a novel compound AAPB with dual effects of neuroprotection and cerebral blood flow improvement. AAPB significantly reduced cerebral infarction and neural function deficit in tMCAO rats, pMCAO rats, and IS rhesus monkeys, as well as displayed exceptional safety profiles and excellent pharmacokinetic properties in rats and dogs. AAPB has now entered phase I of clinical trials fighting IS in China.

Aralia taibaiensi, widely distributed in western China, particularly in the Qinba Mountains, has been utilized as a folk medicine for treating diabetes, gastropathy, rheumatism, and cardiovascular diseases. Saponins from A. taibaiensis (sAT) have demonstrated protective effects against oxidative stress and mitochondrial dysfunction induced by ischemia/reperfusion (I/R). However, the underlying mechanisms remain unclear. In vivo, middle cerebral artery occlusion/reperfusion (MCAO/R) induced inflammatory infiltration, neuronal injury, cell apoptosis, mitochondrial dysfunction, and oxidative stress in the ischaemic penumbra, which were effectively mitigated by sAT. sAT increased the mRNA and protein expression levels of apelin and its receptor apelin/apelin receptors (ARs) both in vivo and in vitro. (Ala13)-Apelin-13 (F13A) and small interfering RNA (siRNA) abolished the regulatory effects of sAT on neuroprotection mediated by adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK)/protein kinase B (Akt). Furthermore, sAT induced apelin/AR expression by simultaneously inhibiting P38 mitogen-activated protein kinase (P38 MAPK)/activating transcription factor 4 (ATF4) and upregulating hypoxia-inducible factor-1α (HIF-1α). Our findings indicate that sAT regulates apelin/AR/AMPK by inhibiting P38 MAPK/ATF4 and upregulating HIF-1a, thereby suppressing oxidative stress and mitochondrial dysfunction.
Animals ; Reperfusion Injury/prevention & control* ; Aralia/chemistry* ; Saponins/administration & dosage* ; AMP-Activated Protein Kinases/genetics* ; Male ; Apelin/genetics* ; Signal Transduction/drug effects* ; Neuroprotective Agents/administration & dosage* ; Brain Ischemia/genetics* ; Rats, Sprague-Dawley ; Rats ; Oxidative Stress/drug effects* ; Apelin Receptors/genetics* ; Humans ; Apoptosis/drug effects* ; Mice

Objective:A mineralized gelatin methacryloyl/hyaluronic acid methacryloyl (GelMA/HAMA) double network hydrogel was constructed, its performance was characterized, and its cell compatibility was studied.Methods:The hydrogel was constructed by photocrosslinking technology, and the biomimetic mineralized hydrogel was prepared by alternating mineralization with calcium and phosphorus solution. The hydrogel was mineralized for three times, for 24 h each time. The control groups were the non-mineralized groups, named the GelMA-0 group and GelMA/HAMA-0 group, respectively. The experimental groups were the mineralized treatment groups. The GelMA hydrogel and GelMA/HAMA double network hydrogel mineralized for 1, 2 and 3 times were named the GelMA-1, 2 and 3 group and GelMA/HAMA-1, 2 and 3 group, respectively. The microstructure of the mineralized hydrogel was characterized by scanning electron microscope and energy dispersive X-ray spectroscopy. The chemical composition of the mineralized hydrogel was characterized by Fourier transform infrared spectroscopy and X-ray diffraction. The mineralization rate of the mineralized hydrogel was evaluated by the ashing method. The compressive strength of the mineralized hydrogel was evaluated by a compression test. The cell compatibility of bone marrow mesenchymal stem cells (BMSCs) on the mineralized hydrogel surface was evaluated by a cell counting kit-8 assay and living/dead cell staining experiment. The datas were analyzed by one-way analysis of variance and Tukey test.Results:With the increase in the number of mineralization cycles, the mineralized layer gradually thickened, and the mineral layer on the cross section of the hydrogel uniformly penetrated into the interior of the hydrogel, with the amount of internal mineral deposition increased. The microstructure of the hydrogel and the distribution of inorganic particles also changed. The surface of the GelMA-3 group and the GelMA/HAMA-3 group contained Ca and P elements, and the distribution was consistent. The inorganic particles generated by mineralization may be immature hydroxyapatite (HAP) crystal precursors. To further verify the chemical composition of inorganic particles, the GelMA-0 and 3 groups as well as the GelMA/HAMA-0 and 3 groups of hydrogels showed GelMA amide Ⅰ, Ⅱ and Ⅲ bands. The GelMA-3 group and GelMA/HAMA-3 group hydrogels contained phosphate, and the diffraction peaks confirmed that the inorganic particles are mainly HAP crystal precursors with low crystallinity. The mineralization rates of the GelMA-1, 2 and 3 groups were (12.48±1.06)%, (21.12±0.62)% and (27.31±0.45)%, while those of the GelMA/HAMA-1, 2 and 3 groups were (15.54±1.03)%, (23.39±0.25)% and (32.26±0.62)%, and the compressive elastic modulus of the GelMA-0, 1, 2 and 3 groups were (69.01±1.04, 91.76±2.05, 105.16±2.95, 131.65±2.21) kPa, and those of the GelMA/HAMA-0, 1, 2 and 3 groups were (270.76±4.56, 347.47±4.60, 388.98±6.96, 430.6±15.47) kPa. Under the same cyclic mineralization times, the mineralization rates and compressive elastic modulus of the GelMA/HAMA double network hydrogel were significantly higher than those of the GelMA hydrogel (all P<0.01). The cell proliferation rates of BMSCs on the GelMA/HAMA-0, 1, 2 and 3 hydrogel surfaces were (49.80±3.38)%, (52.32±1.28)%, (58.00±4.64)% and (62.46±2.74)% on the first day of culture, (58.86±3.36)%, (58.26±3.45)%, (73.08±2.61)% and (76.40±3.45)% on the third day of culture, and (85.89±4.23)%, (90.75±3.21)%, (103.35±4.11)% and (113.42±3.40)% on the fifth day of culture. The cell proliferation rates of the GelMA/HAMA-3 group were significantly higher than those of GelMA/HAMA-0 and 1 groups (all P<0.01). Living/dead cell staining experiment showed that BMSCs on the surface of the GelMA/HAMA-0, 1, 2 and 3 groups were dominated by living cells on the third and fifth days of culture. Conclusions:The mineralized GelMA/HAMA double network hydrogel was constructed, which significantly improved the mineralization rate, mechanical performance and cell compatibility of the biomimetic mineralized hydrogel.

In vivo, cells exist within the mechanical microenvironment of the extracellular matrix (ECM), and their biological processes are regulated by various mechanical factors. However, existing technology limits the direct study of the interaction between cells and ECM in vivo. Using hydrogel to mimic the natural ECM and to construct a suitable mechanical microenvironment for isolated cells, which indirectly reflects the cell-ECM interactions in real organisms through in vitro studies. Thus, in this review, the effects of mechanical factors in hydrogel on different types of cells were summarized, and the development of cell mechanical detection technology using hydrogel as carriers was introduced. Moreover, the future work of using hydrogel to study cell mechanical behavior and related detection technology, as well as standardized preparation, was discussed.

Dynamic hydrogel is three-dimensional networks of hydrophilic polymer formed by dynamic reversible cross-linked bonds. It is widely used in the field of bone repair therapy. The dynamic reversible cross-linked bonds in the dynamic hydrogel endows it with shear-thinning rheological properties, resulting in excellent self-healing, injectability and tunable mechanical properties. In this review, the formation mechanism of dynamic hydrogel was summarized, including non-covalent interaction and dynamic covalent interaction. The advantages and disadvantages of the various cross-linked methods used to form dynamic hydrogel were discussed. The applications of dynamic hydrogel in bone repair therapy were summarized, including haemostasis for filling bone defects, drug delivery, modulation of stem cell behavior, and biomimetic mineralization, to provide a reference for the future development of dynamic hydrogel for bone repair therapy.

Osteoporosis and cardiovascular calcification,two major age-related chronic diseases that China is confronting today,pose serious threats to public health.Previous studies have reported overlapping connections in the pathological processes and molecular mechanisms of these two diseases,particularly concerning inflammation,oxidative stress,and dysregulation of mineral metabolism,and that these two diseases tend to share common pathogenic factors.However,research exploring the comorbidity mechanisms of the two diseases remains limited in both depth and scope,largely due to the lack of widely accepted comorbidity animal models.Herein,we analyzed the latest research findings on the comorbidity mechanisms of vascular calcification and osteoporosis,focusing on summarizing the animal disease models currently in extensive use and the relevant evaluation criteria.We aim to provide new references for comorbidity research models and offer scientific evidence for future studies on pathological mechanisms and the development of new therapeutic strategies.

AIM: To study the protective effect of fenofibrate on diabetic retinal neurodegeneration and observe its effect on miR-26a-5p and its target gene PTEN in the retinal of diabetic mice.METHODS: Diabetic mice models were established and they were gavaged by fenofibrate. H& E staining and transmission electron microscopy were used to observe the impairments of retinal neurons. Real-time PCR was used to examine the expression of miR-26a-5p, and Western blotting was employed to measure the expression of phosphatase and tensin homologue(PTEN)in the retina of diabetic mice. The expression level of nuclear factor-κB(NF-κB), interleukin-1β(IL-1β)and the morphology of neural tissues were observed.RESULTS: When compared with the diabetic mice, fenofibrate significantly attenuated the damage to retinal ganglion cells and the atrophy of retinal nerve fiber layer. While the level of miR-26a-5p was increased and the levels of PTEN and inflammatory mediators were significantly decreased in the retina of fenofibrate treated diabetic mice, with significant statistical significance(P<0.05).CONCLUSIONS: Fenofibrate protects against diabetic retinal neurodegeneration by upregulating miR-26a-5p and inhibiting PTEN, attenuating the inflammatory response and alleviating retinal cell injury.

Background and objective The pathological types of lung ground glass nodules(GGNs)show great significance to the clinical treatment.This study was aimed to predict pathological types of GGNs based on computed tomog-raphy(CT)quantitative parameters.Methods 389 GGNs confirmed by postoperative pathology were selected,including 138 cases of precursor glandular lesions[atypical adenomatous hyperplasia(AAH)and adenocarcinoma in situ(AIS)],109 cases of microinvasive adenocarcinoma(MIA)and 142 cases of invasive adenocarcinoma(IAC).The morphological characteristics of nodules were evaluated subjectively by radiologist,as well as artificial intelligence(AI).Results In the subjective CT signs,the maximum diameter of nodule and the frequency of spiculation,lobulation and pleural traction increased from AAH+AIS,MIA to IAC.In the AI quantitative parameters,parameters related to size and CT value,proportion of solid component,energy and entropy increased from AAH+AIS,MIA to IAC.There was no significant difference between AI quantitative parameters and the subjective CT signs for distinguishing the pathological types of GGNs.Conclusion AI quantitative parameters were valu-able in distinguishing the pathological types of GGNs.