Nanoporous Titanium Implant Surface Accelerates Osteogenesis via the Piezo1/Acetyl-CoA/ß-Catenin Pathway.

Osseointegration is the most important factor determining implant success. The surface modification of TiO2 nanotubes prepared by anodic oxidation has remarkable advantages in promoting bone formation. However, the mechanism behind this phenomenon is still unintelligible. Here we show that the nanomorphology exhibited open and clean nanotube structure and strong hydrophilicity, and the nanomorphology significantly facilitated the adhesion, proliferation, and osteogenesis differentiation of stem cells. Exploring the mechanism, we found that the nanomorphology can enhance mitochondrial oxidative phosphorylation (OxPhos) by activating Piezo1 and increasing intracellular Ca2+. The increase in OxPhos can significantly uplift the level of acetyl-CoA in the cytoplasm but not significantly raise the level of acetyl-CoA in the nucleus, which was beneficial for the acetylation and stability of ß-catenin and ultimately promoted osteogenesis. This study provides a new interpretation for the regulatory mechanism of stem cell osteogenesis by nanomorphology.

Achieving High-Strength and Toughness in a Mg-Gd-Y Alloy Using Multidirectional Impact Forging.

High strength and toughness are achieved in the Mg-4.96Gd-2.44Y-0.43Zr alloy by multidirectional impact forging (MDIF). The forged sample has a fine-grained microstructure with an average grain size of ~5.7 µm and a weak non-basal texture, and it was characterized by an optical microscope (OM), scanning electron microscope (SEM), and electron back-scattering diffraction (EBSD). Tensile results exhibit the tensile yield strength (TYS) and static toughness (ST) of as-homogenized alloy dramatically increased after forging and aging, i.e., the TYS increased from 135-5+4 MPa to 337-2+2 MPa, and the ST enhanced from 22.0-0.5+0.3 MJ/m3 to 50.4-5.4+5.3 MJ/m3. Specifically, the forged Mg-Gd-Y-Zr alloy owns higher TYS than that of commercial rolled WE54 (Mg-5.25Y-3.5Nd-0.5Zr) and WE43 (Mg-4.0Y-3.0Nd-0.5Zr) alloys.

ULK1-regulated autophagy: A mechanism in cellular protection for ALDH2 against hyperglycemia.

Mitochondrial aldehyde dehydrogenase 2 (ALDH2), an important enzyme in the elimination of toxic aldehydes, is involved in cardioprotection against diabetes mellitus. This study was designed to examine the mechanism behind ALDH2-offered protection against high glucose exposure with a focus on autophagy. H9C2 cells were cultured with normal or high glucose medium in the presence or absence of the ALDH2 agonist Alda-1. GFP-LC3 puncta and immunofluorescence were employed to assess autophagosome formation. Western blotting was applied to evaluate autophagy protein markers Atg5, LC3, p62, ULK1 phosphorylation and ALDH2. JC-1 staining was used to monitor mitochondrial membrane potential and mitochondrial injury. CCK-8 and TUNEL assays were employed for apoptosis and cell viability. Our results indicated that high glucose promoted cell death and decreased cell viability. Levels of autophagy protein marker Atg5, and LC3B were decreased and level of p62 was elevated in hyperglycemic condition, the effects of which were reversed by ALHD2. High glucose lowered mitochondrial membrane potential, the effect of which was accentuated by ULK1 knock-down. All these high glucose-induced responses were negated by Alda-1 along with upregulated autophagy. The autophagy inhibitor 3-MA and lysosomal inhibitor bafilomycin A1 cancelled off whereas autophagy inducer rapamycin mimicked the Alda-1-offered protection against high glucose. High glucose suppressed phosphorylation of ULK1, the effect of which was mitigated by Alda-1. Knock-down of ULK1 using siRNA negated Alda-1-induced upregulation of autophagosome accumulation and LC3 expression. High glucose-dampened autophagy was also confirmed using GFP-LC3 puncta, and immunofluorescence. Taken together, these data suggested that ULK1 played a crucial role in ALDH2-offered protective effect against high glucose exposure-induced cardiomyocyte injury through regulation of autophagy.

Irregular Implant Design Decreases Periimplant Stress and Strain Under Oblique Loading.

OBJECTIVES: To investigate whether a different implant geometry with the same potential contact surface area (PCSA) affects the principal stress and strains in bone. MATERIAL AND METHODS: Three-dimensional finite-element models were created with a single endosseous implant embedded in bone. The irregular (IR) dental root-analog implant and regular (R) cylindrical implant with the same PCSA 350 mm were modeled, keeping the size of the thinnest implant wall 0.8 mm, and the thinnest bone wall 1 mm. The regular or irregular abutments were either 4.5 mm lower than the platform of the implants or 5 mm higher than the platform of the implants, both with the taper 1.44°. A 100 N vertical or 100 N vertical/50 N horizontal occlusal loading was applied. The biomechanical behaviors of periimplant bone were recorded. RESULTS: The IR implant design experienced lower periimplant stress and strain under oblique loading than that of R implant design. In the IR implant design, comparable stress in bone, implant, and abutment were found under 100 N vertical loading or 100 N vertical/50 N horizontal loading. In the R implant design, much higher stress in bone, implant, and abutment were found under 100 N vertical/50 N horizontal loading than that under 100 N vertical loading. CONCLUSION: Irregular dental root-analog implant is a biomechanically favorable design principle for decreasing periimplant stress and strain under oblique loading.

Influence of Different Abutment Designs on the Biomechanical Behavior of Dental Root-Analog Implant: A Three-Dimensional Finite Element Analysis.

OBJECTIVE: The aim of this study was to evaluate cross-sectional area of the abutments, strain distribution in the periimplant bone, stress in the abutments and dental root-analog implant by different abutment design under different loading conditions, through three-dimensional finite element analysis. METHODS: Two three-dimensional finite element models were established. Two types of abutments, oval cross section abutment (OCSA) and circular cross section abutment (CCSA) were designed, keeping the size of the thinnest implant wall 0.75 mm. Two types of load were applied to the abutment in each model: 100 N vertical load (V), 100 N vertical/50 N horizontal load (VH). The biomechanical behaviors of abutments, implants, and periimplant bone were recorded. RESULTS: The cross-section area of OCSA is 36.5% larger than that of CCSA. In implants, the maximum von Mises stress value in OCSA design was 24.6% lower than that in CCSA design under V and under VH. In abutments, the maximum von Mises stress value in OCSA design was 40.0% lower than that in CCSA design under V, the maximum von Mises stress value in OCSA design was 12.2% lower than that in CCSA design under VH. CONCLUSIONS AND CLINICAL SIGNIFICANCE: The irregular design offers advantages over regular design.

Accuracy Assessment of Three-dimensional Surface Reconstructions of In vivo Teeth from Cone-beam Computed Tomography.

BACKGROUND: The accuracy of three-dimensional (3D) reconstructions from cone-beam computed tomography (CBCT) has been particularly important in dentistry, which will affect the effectiveness of diagnosis, treatment plan, and outcome in clinical practice. The aims of this study were to assess the linear, volumetric, and geometric accuracy of 3D reconstructions from CBCT and to investigate the influence of voxel size and CBCT system on the reconstructions results. METHODS: Fifty teeth from 18 orthodontic patients were assigned to three groups as NewTom VG 0.15 mm group (NewTom VG; voxel size: 0.15 mm; n = 17), NewTom VG 0.30 mm group (NewTom VG; voxel size: 0.30 mm; n = 16), and VATECH DCTPRO 0.30 mm group (VATECH DCTPRO; voxel size: 0.30 mm; n = 17). The 3D reconstruction models of the teeth were segmented from CBCT data manually using Mimics 18.0 (Materialise Dental, Leuven, Belgium), and the extracted teeth were scanned by 3Shape optical scanner (3Shape A/S, Denmark). Linear and volumetric deviations were separately assessed by comparing the length and volume of the 3D reconstruction model with physical measurement by paired t- test. Geometric deviations were assessed by the root mean square value of the imposed 3D reconstruction and optical models by one-sample t-test. To assess the influence of voxel size and CBCT system on 3D reconstruction, analysis of variance (ANOVA) was used (µ = 0.05). RESULTS: The linear, volumetric, and geometric deviations were -0.03 ± 0.48 mm, -5.4 ± 2.8%, and 0.117 ± 0.018 mm for NewTom VG 0.15 mm group; -0.45 ± 0.42 mm, -4.5 ± 3.4%, and 0.116 ± 0.014 mm for NewTom VG 0.30 mm group; and -0.93 ± 0.40 mm, -4.8 ± 5.1%, and 0.194 ± 0.117 mm for VATECH DCTPRO 0.30 mm group, respectively. There were statistically significant differences between groups in terms of linear measurement (P < 0.001), but no significant difference in terms of volumetric measurement (P = 0.774). No statistically significant difference were found on geometric measurement between NewTom VG 0.15 mm and NewTom VG 0.30 mm groups (P = 0.999) while a significant difference was found between VATECH DCTPRO 0.30 mm and NewTom VG 0.30 mm groups (P = 0.006). CONCLUSIONS: The 3D reconstruction from CBCT data can achieve a high linear, volumetric, and geometric accuracy. Increasing voxel resolution from 0.30 to 0.15 mm does not result in increased accuracy of 3D tooth reconstruction while different systems can affect the accuracy.

Cardiac-Specific Knockout of ETA Receptor Mitigates Paraquat-Induced Cardiac Contractile Dysfunction.

Paraquat (1,1'-dim ethyl-4-4'-bipyridinium dichloride), a highly toxic quaternary ammonium herbicide widely used in agriculture, exerts potent toxic prooxidant effects resulting in multi-organ failure including the lung and heart although the underlying mechanism remains elusive. Recent evidence suggests possible involvement of endothelin system in paraquat-induced acute lung injury. This study was designed to examine the role of endothelin receptor A (ETA) in paraquat-induced cardiac contractile and mitochondrial injury. Wild-type (WT) and cardiac-specific ETA receptor knockout mice were challenged to paraquat (45 mg/kg, i.p.) for 48 h prior to the assessment of echocardiographic, cardiomyocyte contractile and intracellular Ca(2+) properties, as well as apoptosis and mitochondrial damage. Levels of the mitochondrial proteins for biogenesis and oxidative phosphorylation including UCP2, HSP90 and PGC1α were evaluated. Our results revealed that paraquat elicited cardiac enlargement, mechanical anomalies including compromised echocardiographic parameters (elevated left ventricular end-systolic and end-diastolic diameters as well as reduced factional shortening), suppressed cardiomyocyte contractile function, intracellular Ca(2+) handling, overt apoptosis and mitochondrial damage. ETA receptor knockout itself failed to affect myocardial function, apoptosis, mitochondrial integrity and mitochondrial protein expression. However, ETA receptor knockout ablated or significantly attenuated paraquat-induced cardiac contractile and intracellular Ca(2+) defect, apoptosis and mitochondrial damage. Taken together, these findings revealed that endothelin system in particular the ETA receptor may be involved in paraquat-induced toxic myocardial contractile anomalies possibly related to apoptosis and mitochondrial damage.

The effect of local delivery of adiponectin from biodegradable microsphere-scaffold composites on new bone formation in adiponectin knockout mice.

Adiponectin (APN) is the most abundant adipocyte-secreted adipokine; it regulates energy homeostasis and exerts well-characterized insulin-sensitizing properties. Previous studies have verified that globular adiponectin (gAPN) is also involved in bone metabolism, although observations have been controversial. The purpose of the current study is to use an APN-knockout (APN-KO) mouse model to evaluate the local delivery of gAPN to new bone formation. Using chitosan microspheres (CMs), we found that following an initial burst at 1 week, the release behavior of gAPN from the scaffold was sustained in a linear manner for the first 4 weeks, followed by a slower, more stable release from week 5 onwards. Interestingly, PLGA/ß-TCP/CM-loaded gAPN scaffolds implanted in APN-KO mice increased bone formation and mineralization, and enhanced osteogenic marker expression 28 days post-implantation. gAPN also promoted preosteoblast (MC3T3-E1) cellular proliferation in vitro. In MC3T3-E1 cells, adaptor protein-containing pleckstrin homology domain, phosphotyrosine domain, leucine zipper motif (APPL1) and phosphoinositide 3-kinase (PI3K) expression was upregulated in a time-dependent manner upon gAPN treatment, while APPL1 small interfering RNA (siRNA) pre-treatment reversed this enhanced expression. In conclusion, modified bone graft substitutes loaded with gAPN increase bone formation and mineralization in part by promoting osteoblast proliferation via the APPL1/PI3K pathway.

The Osteogenesis Effect and Underlying Mechanisms of Local Delivery of gAPN in Extraction Sockets of Beagle Dogs.

A plastic and biodegradable bone substitute consists of poly (L-lactic-co-glycolic) acid and 30 wt % ß-tricalcium phosphate has been previously fabricated, but its osteogenic capability required further improvement. We investigated the use of globular adiponectin (gAPN) as an anabolic agent for tissue-engineered bone using this scaffold. A qualitative analysis of the bone regeneration process was carried out using µCT and histological analysis 12 weeks after implantation. CBCT (Cone Beam Computed Tomography) superimposition was used to characterise the effect of the different treatments on bone formation. In this study, we also explored adiponectin's (APN) influence on primary cultured human jaw bone marrow mesenchymal stem cells gene expressions involved in the osteogenesis. We found OPEN ACCESS Int. J. Mol. Sci. 2015, 16 24947 that composite scaffolds loaded with gAPN or bone morphogenetic protein 2 (BMP2) exhibited significantly increased bone formation and mineralisation following 12 weeks in the extraction sockets of beagle dogs, as well as enhanced expression of osteogenic markers. In vitro investigation revealed that APN also promoted osteoblast differentiation of primary cultured human jaw bone marrow mesenchymal stem cells (h-JBMMSCs), accompanied by increased activity of alkaline phosphatase, greater mineralisation, and production of the osteoblast-differentiated genes osteocalcin, bone sialoprotein and collagen type I, which was reversed by APPL1 siRNA. Therefore, the composite scaffold loaded with APN exhibited superior activity for guided bone regeneration compared with blank control or Bio-Oss® (a commercially available product). The composite scaffold with APN has significant potential for clinical applications in bone tissue engineering.

[Validation of the American College of Rheumatology classification criteria for primary Sjogren's syndrome in Chinese patients].

OBJECTIVE: To validate the American College of Rheumatology Classification (ACR) Criteria (2012) for the diagnosis of primary Sjogren's syndrome in Chinese patients. METHODS: All patients involved in this study came from the Department of Oral Medicine Peking University Stomatology Hospital. They were devided into two groups of pSS and non-pSS according to the diagnoses made by two experts. Both groups of the patients had completed medical records kept in the hospital. RESULTS: A total of 239 pSS patients (160 with labial salivary gland biopsy, and 79 without biopsy) and 52 age-matched non-pSS patients [(55.17±14.295),and (55.90±13.38) years old, P>0.05] (9 with biopsy, and 43 without biopsy) were involved in this study. The sensitivity and specificity of ACR criteria in diagnosing pSS were 90.37 % and 88.46 % respectively. The positive and negative likelihood ratios were 7.83 and 0.109, respectively. The sensitivities of ACR criteria in diagnosing pSS patients with and without labial biopsy were 88.75% and 93.67 %, respectively, with specificities of 88.89% and 88.37%, respectively. The most sensitive item adopted in ACR criteria was the ocular staining score with a sensitivity of 85.77%, and the most specific item was the labial salivary gland biopsy, with a specificity of 88.89%. CONCLUSION: The sensitivity and specificity of ACR criteria in diagnosing Chinese pSS patients were relatively high, and may serve as the diagnosis criteria in research and clinical practice. However, the ACR criteria need to be validated and further revised in the future .

Biomechanical optimization of the diameter of distraction screw in distraction implant by three-dimensional finite element analysis.

Three-dimensional (3D) finite element models of a posterior mandibular segment and a distraction implant (DI) were created and assembled in this study. The diameter of distraction screw (DS) was set as input variable, ranging from 1.0 to 3.0mm, to analyze the stress and displacement, in order to obtain an optimal outcome of the DI. The results indicate that when the diameter of DS was 2.0mm, the stresses in jaw bone and DS and the displacement of DS reached a relatively low range. The diameter of DS significantly affects the stress distribution in DI and surrounding bone. The present study demonstrates that from clinical and biomechanical points of view, the optimal diameter of DS is 2.0mm.

Cold stress accentuates pressure overload-induced cardiac hypertrophy and contractile dysfunction: role of TRPV1/AMPK-mediated autophagy.

Severe cold exposure and pressure overload are both known to prompt oxidative stress and pathological alterations in the heart although the interplay between the two remains elusive. Transient receptor potential vanilloid 1 (TRPV1) is a nonselective cation channel activated in response to a variety of exogenous and endogenous physical and chemical stimuli including heat and capsaicin. The aim of this study was to examine the impact of cold exposure on pressure overload-induced cardiac pathological changes and the mechanism involved. Adult male C57 mice were subjected to abdominal aortic constriction (AAC) prior to exposure to cold temperature (4 °C) for 4 weeks. Cardiac geometry and function, levels of TRPV1, mitochondrial, and autophagy-associated proteins including AMPK, mTOR, LC3B, and P62 were evaluated. Sustained cold stress triggered cardiac hypertrophy, compromised depressed myocardial contractile capacity including lessened fractional shortening, peak shortening, and maximal velocity of shortening/relengthening, enhanced ROS production, and mitochondrial injury, the effects of which were negated by the TRPV1 antagonist SB366791. Western blot analysis revealed upregulated TRPV1 level and AMPK phosphorylation, enhanced ratio of LC3II/LC3I, and downregulated P62 following cold exposure. Cold exposure significantly augmented AAC-induced changes in TRPV1, phosphorylation of AMPK, LC3 isoform switch, and p62, the effects of which were negated by SB366791. In summary, these data suggest that cold exposure accentuates pressure overload-induced cardiac hypertrophy and contractile defect possibly through a TRPV1 and autophagy-dependent mechanism.

[Preliminary study of the relationship between tumor like Sjögren's syndrome and malignant lymphoma].

OBJECTIVE: To investigate the clinical and laboratory characteristics of tumor like Sjögren's syndrome (TLSS) patients and non-tumor like Sjögren's syndrome (NTLSS) and the incidence of lymphoma in patients of Sjögren's syndrome (SS). METHODS: A retrospective analysis was carried out in 199 primary SS (including TLSS) patients who were recruited in Peking University School and Hospital of Stomatology from 1998 to 2010. Clinical and laboratory information were collected. The patients were divided into two groups: TLSS (n = 25) and NTLSS (n = 174). Clinical and laboratory characteristics were compared between these two groups by a statistical analysis. RESULTS: Of the 25 TLSS patients, 23 had enlargements of parotid glands and 2 had enlargements of submandibular glands. There were significant differences of salivary scintigraphy appearance (P = 0.018), hypergammaglobulinemia (P = 0.014), rheumatoid factor positive rate (P = 0.001), formation of the ectopic germinal centers (P = 0.014), double positive rate of anti-SSA antibody and anti-SSB antibody (P < 0.001) between the TLSS and NTLSS patients. Among the 25 TLSS patients, 3 developed lymphomas, accounting for 1.5% (3/199) of the total 199 patients and 12% (3/25) of the TLSS patients. Lymphoma subtypes included one diffused large B-cell lymphoma and two mucosa-associated lymphoid tissue lymphoma. There was no lymphoma detected in NTLSS patients. CONCLUSIONS: There are clinical and laboratory differences between TLSS and NTLSS patients, with a more tendency to develop lymphomas in TLSS patients.