Cardiorenal metabolic syndrome and diabetic cognopathy

The prevalence of the cardiorenal metabolic syndrome (CRS) is increasing in parallel with obesity, type 2 diabetes mellitus, Alzheimer's disease, and other forms of dementia. Along with metabolic, inflammatory, and immunological abnormalities, there is maladaptive structural remodeling of the heart, kidney, and brain. The term 'diabetic cognopathy' (DC) may be used when discussing functional and structural changes in the brain of the diabetic patient. DC likely represents an advanced form of these changes in the brain that evolve with increasing duration of the CRS and subsequent clinical diabetes. We posit that DC develops due to a convergence of aging, genetic and lifestyle abnormalities (overnutrition and lack of exercise), which result in multiple injurious metabolic and immunologic toxicities such as dysfunctional immune responses, oxidative stress, inflammation, insulin resistance, and dysglycemia (systemically and in the brain). These converging abnormalities may lead to endothelial blood-brain barrier tight junction/adherens junction (TJ/AJ) complex remodeling and microglia activation, which may result in neurodegeneration, impaired cognition, and dementia. Herein, we describe the brain ultrastructural changes evolving from a normal state to maladaptive remodeling in rodent models of CRS including microglia activation/polarization and attenuation and/or loss of the TJ/AJ complexes, pericytes and astrocytes of the neurovascular unit. Further, we discuss the potential relationship between these structural changes and the development of DC, potential therapeutic strategies, and future directions.

Antagonistic and synergistic effects of bone morphogenetic protein 2/7 and all-trans retinoic acid on the osteogenic differentiation of rat bone marrow stromal cells

The osteogenesis of bone marrow stromal cells (BMSCs) is of paramount importance for the repair of large-size bone defects, which may be compromised by the dietary-accumulated all-trans retinoic acid (ATRA). We have shown that heterodimeric bone morphogenetic protein 2/7 (BMP2/7) could induce bone regeneration in a significantly higher dose-efficiency in comparison with homodimeric BMPs. In this study, we evaluated the effects of ATRA and BMP2/7 on the proliferation, differentiation, mineralization and osteogenic genes. ATRA and BMP2/7 exhibited both antagonistic and synergistic effects on the osteogenesis of BMSCs. ATRA significantly inhibited proliferation and expression of osteocalcin but enhanced the activity of alkaline phosphatase of BMSCs. On day 21, 50 ng/mL BMP2/7 could antagonize the inhibitive effects of ATRA and significantly enhance osteogenesis of BMSCs. These findings suggested a promising application potential of heterodimeric BMP2/7 in clinic to promote bone regeneration for the cases with dietary accumulated ATRA.

Pressure and inflammatory stimulation induced increase of cadherin-11 is mediated by PI3K/Akt pathway in synovial fibroblasts from temporomandibular joint

OBJECTIVE

The goal of the study was to investigate the expression of cadherin-11 in synovial fibroblasts (SFs) under mechanical or inflammatory stimuli, and its potential relationship with PI3K/Akt signaling pathway.

METHODS

SFs separated from rat temporomandibular joint (TMJ) were treated with hydrostatic pressures (HP) of 30, 60, 90, and 120 kPa, as well as tumor necrosis factor-α (TNF-α) for 12, 24, 48, and 72 h. The location of cadherin-11 was observed by immunofluorescence microscopy, and its expression was detected by real-time PCR and Western blot. We also studied the activation of PI3K/Akt signaling pathway in SFs with HP or TNF-α stimulation.

RESULTS

The results showed that increased expression of cadherin-11 could be found in the cell-cell contact site of SFs in response to HP and inflammatory stimulation. The mRNA and protein expression of cadherin-11 was positively correlated with the intensity of HP and the duration time of TNF-α treatment. Increased expression of vascular endothelial growth factor-D (VEGF-D) and activation of Akt were also found. Treatment with PI3K inhibitor LY294002 attenuated the pressure or inflammatory cytokine induction increases of cadherin-11, VEGF-D, and FGF-2 both in mRNA and protein levels.

CONCLUSIONS

These findings suggest that cadherin-11 may play important roles in SFs following exposure to mechanical loading and inflammatory stimulation. In addition, PI3K/Akt pathway was associated with pressure or inflammation-induced cadherin-11 expression, which may involve in the pathogenesis of temporomandibular diseases.

Deproteinized bovine bone functionalized with the slow delivery of BMP-2 for the repair of critical-sized bone defects in sheep

As an alternative to an autologous bone graft, deproteinized bovine bone (DBB) is widely used in the clinical dentistry. Although DBB provides an osteoconductive scaffold, it is not capable of enhancing bone regeneration because it is not osteoinductive. In order to render DBB osteoinductive, bone morphogenetic protein 2 (BMP-2) has previously been incorporated into a three dimensional reservoir (a biomimetic calcium phosphate coating) on DBB, which effectively promoted the osteogenic response by the slow delivery of BMP-2. The aim of this study was to investigate the therapeutic effectiveness of such coating on the DBB granules in repairing a large cylindrical bone defect (8 mm diameter, 13 mm depth) in sheep. Eight groups were randomly assigned to the bone defects: (i) no graft material; (ii) autologous bone; (iii) DBB only; (iv) DBB mixed with autologous bone; (v) DBB bearing adsorbed BMP-2; (vi) DBB bearing a coating but no BMP-2; (vii) DBB bearing a coating with adsorbed BMP-2; and (viii) DBB bearing a coating-incorporated depot of BMP-2. 4 and 8 weeks after implantation, samples were withdrawn for a histological and a histomorphometric analysis. Histological results confirmed the excellent biocompatibility and osteoconductivity of all the grafts tested. At 4 weeks, DBB mixed with autologous bone or functionalized with coating-incorporated BMP-2 showed more newly-formed bone than the other groups with DBB. At 8 weeks, the volume of newly-formed bone around DBB that bore a coating-incorporated depot of BMP-2 was greatest among the groups with DBB, and was comparable to the autologous bone group. The use of autologous bone and BMP-2 resulted in more bone marrow formation. Multinucleated giant cells were observed in the resorption process around DBB, whereas histomorphometric analysis revealed no significant degradation of DBB. In conclusion, it was shown that incorporating BMP-2 into the calcium phosphate coating of DBB induced strong bone formation around DBB for repairing a critical-sized bone defect.

Forward mandibular positioning enhances the expression of Ang-1 and Ang-2 in rabbit condylar chondrocytes

Functional appliances correct dental malocclusion, partly by exerting an indirect mechanical stimulus on the condylar cartilage, initiating novel bone formation in the condyle. Angiopoietin is involved in the angiogenesis associated with novel bone formation. This study aimed to determine the expression of angiopoietin (Ang)‑1 and ‑2 following forward mandibular positioning (FMP) in the condylar chondrocytes of rabbits. Sixty rabbits (age, 8 weeks) were randomly allocated to the experimental and control groups (n=30 per group). In the experimental group, FMP was induced by a functional appliance. Five rabbits from the experimental group and the control group were sacrificed following 3 days and 1, 2, 4, 8 and 12 weeks, respectively. The right temporomandibular joints (TMJs) were collected and the expression of Ang‑1 and -2 was evaluated by immunohistochemical staining. The expression of Ang-1 increased at day 3 and reached a peak at 2 weeks, whereas Ang‑2 reached maximal expression 4 weeks after FMP. Subsequently, the expression of Ang‑1 and ‑2 gradually decreased. Thus, FMP enhanced the expression of Ang‑1 and Ang‑2 in condylar cartilage, which is related to angiogenesis in the process of endochondral ossification.

Association of the polymorphism of MMP2 with the risk and severity of lumbar disc degeneration in the Chinese Han population

OBJECTIVE

The present study aimed to determine whether the -735 C/T polymorphism of the Matrix Metalloproteinase 2 (MMP2) gene is associated with the risk and severity of lumbar disc degeneration (LDD) in the Chinese Han population.

PATIENTS AND METHODS

A total of 1008 patients with LDD and 906 healthy controls were enrolled in this study. The grade of disc degeneration was determined according to Schneiderman's classification for Magnetic Resonance Imaging (MRI). The -735 C/T polymorphism of MMP2 was genotyped using polymerase chain reaction and the restriction fragment length polymorphism method.

RESULTS

The genotype frequency of the -735 C/T polymorphism was in agreement with the Hardy-Weinberg equilibrium (p = 0.087). The frequencies of the -735CT and TT genotypes were significantly lower among LDD patients compared with normal controls (p < 0.001); CT and TT genotype were significantly associated with a decreased risk of LDD compared with the CC genotype (for TT genotype, p = 0.031; OR 0.413; 95% CI 0.184-0.924; for CT genotype, p < 0.001, OR 0.645, 95% CI 0.506-0.822). Patients with LDD showed significantly higher frequencies of the C allele than normal controls (p < 0.001), T allele was significantly associated with a decreased risk of LDD compared with the C allele (p < 0.001; OR 0.631; 95% CI 0.508-0.783). In addition, the -735TT and CT genotypes, as well as the T allele were associated with lower degenerative grades of LDD compared with CC genotype and the C allele, respectively (both p < 0.001).

CONCLUSIONS

The -735 C/T polymorphism of MMP2 may be associated with the risk and severity of LDD in the Chinese Han population.

NEMA NU-4 performance evaluation of PETbox4, a high sensitivity dedicated PET preclinical tomograph

PETbox4 is a new, fully tomographic bench top PET scanner dedicated to high sensitivity and high resolution imaging of mice. This manuscript characterizes the performance of the prototype system using the National Electrical Manufacturers Association NU 4-2008 standards, including studies of sensitivity, spatial resolution, energy resolution, scatter fraction, count-rate performance and image quality. The PETbox4 performance is also compared with the performance of PETbox, a previous generation limited angle tomography system. PETbox4 consists of four opposing flat-panel type detectors arranged in a box-like geometry. Each panel is made by a 24 × 50 pixelated array of 1.82 × 1.82 × 7 mm bismuth germanate scintillation crystals with a crystal pitch of 1.90 mm. Each of these scintillation arrays is coupled to two Hamamatsu H8500 photomultiplier tubes via a glass light guide. Volumetric images for a 45 × 45 × 95 mm field of view (FOV) are reconstructed with a maximum likelihood expectation maximization algorithm incorporating a system model based on a parameterized detector response. With an energy window of 150-650 keV, the peak absolute sensitivity is approximately 18% at the center of FOV. The measured crystal energy resolution ranges from 13.5% to 48.3% full width at half maximum (FWHM), with a mean of 18.0%. The intrinsic detector spatial resolution is 1.5 mm FWHM in both transverse and axial directions. The reconstructed image spatial resolution for different locations in the FOV ranges from 1.32 to 1.93 mm, with an average of 1.46 mm. The peak noise equivalent count rate for the mouse-sized phantom is 35 kcps for a total activity of 1.5 MBq (40 µCi) and the scatter fraction is 28%. The standard deviation in the uniform region of the image quality phantom is 5.7%. The recovery coefficients range from 0.10 to 0.93. In comparison to the first generation two panel PETbox system, PETbox4 achieves substantial improvements on sensitivity and spatial resolution. The overall performance demonstrates that the PETbox4 scanner is suitable for producing high quality images for molecular imaging based biomedical research.

FcγRI is required for TGFβ2-treated macrophage-induced tolerance

Macrophages treated with TGFβ2 (TGFβ2-Mϕ) and antigen are highly tolerogenic in vivo, and induce antigen-specific and long-lasting tolerance in both naïve and primed mice via induction of suppressor/regulatory T cells. In this study, we examined the molecular pathways, including the requirements for Smad-dependent signaling, that are involved in the induction and function of tolerogenic TGFβ2-Mϕ. Treatment of murine macrophages with TGFβ2 induced translocation of Smad2/3 to the nucleus, and impairment of Smad3-, but not Smad2-, dependent signaling inhibited the tolerogenic function of a TGFβ2-treated murine macrophage cell line. Gene expression in murine macrophages treated with TGFβ2 was evaluated by microarray analysis. The FcγRI gene was one of a number of immune-related genes differentially expressed in TGFβ2-Mϕ, and appeared to be critical for tolerance in this system, since TGFβ2-Mϕ from FcγRI deficient mice were unable to induce tolerance. The role that FcγRI plays in TGFβ2-Mϕ-mediated tolerance is currently unclear. The results of this study provide important information about the factors that are critical for the induction of TGFβ2-Mϕ-mediated tolerance, and a better understanding of these mechanisms could lead to the development of more effective tolerance-inducing strategies for the treatment of autoimmune/inflammatory diseases.

Mandibular lateral shift induces the increased expression of TGF-β, VEGF, and Col-II in the condyle of rat temporomandibular joints

OBJECTIVE

The present study evaluates histologic changes to and expression of angiogenic factors in rats with mandibular functional shift (MFS).

STUDY DESIGN

After 1, 2, and 4 weeks of MFS, rats in the experimental and control groups were killed. Histologic micrographs of the ipsilateral condyle cartilage were obtained. The localization and expression of vascular endothelial growth factor (VEGF), transforming growth factor beta (TGF-β), and type-II collagen (Col-II) in temporomandibular joints (TMJs) were evaluated through immunohistochemical staining.

RESULTS

The results showed that structural changes in the condyle cartilage could be observed 2 weeks after MFS. TGF-β expression reached its peak 2 weeks post-MFS, whereas VEGF and Col-II reached their peaks 4 weeks posttreatment.

CONCLUSIONS

Compressive forces applied to the TMJ could enhance the expressions of VEGF, TGF-β, and Col-II, and activate angiogenesis. The proteins appear to play important roles in the remodeling of the TMJ.

Trepanation and curettage treatment for acute implant periapical lesions

Six dental implants in six patients with periapical lesions were inserted and underwent trepanation and thorough curettage. During surgery, the lesion area was irrigated with copious natural saline and chlorhexidine and the bone defects were treated with tetracycline paste. The six implants were stable and asymptomatic postoperatively. The implants were loaded after 3 months. Radiologically, the radiolucency in the apical part disappeared gradually. These prostheses have functioned satisfactorily with no further complication during the follow-up period. For cases in which small lesions initially appear soon after implant placement, trepanation and curettage of the periapical lesion without resection of the apical part of the implant or bone substitute material and/or autogenous bone grafting is an effective management option. A rapid and exact diagnosis is important for treating implant periapical lesions.

Preliminary identification of potential PDZ-domain proteins downstream of ephrin B2 during osteoclast differentiation of RAW264.7 cells

The EphB4 receptor and ephrin B2 ligand were recently reported to influence the coupling between osteoclasts and osteoblasts in bone biology, but their downstream signaling pathways remain unclear. This study focuses on the preliminary identification of downstream PDZ-domain proteins involved in EphB4/ephrin B2 reverse signaling in osteoclasts. Similarly to primary osteoclast precursors isolated from the bone, we observed that the RAW264.7 cell line, a mouse monocyte/macrophage cell line that is used in conventional assays for osteoclast function, expressed ephrin B2 during RANKL-induced osteoclast differentiation, and that preclustered EphB4 inhibited this osteoclast differentiation. The results demonstrate that RAW264.7 cells provide a good model for further research of EphB4/ephrin B2 signaling in osteoclasts. Immunofluorescence staining and Western blot analysis revealed that all of the eight PDZ-domain proteins previously reported to interact with ephrin B ligands were expressed in the differentiated RAW264.7 osteoclasts. However, in a co-immunoprecipitation assay, only Dishevelled 2 (Dvl2) among eight PDZ-domain proteins tested co-precipitated with ephrin B2 and vice versa, suggesting an endogenous interaction between Dvl2 and ephrin B2 in RANKL-induced osteoclasts. Furthermore, preclustered EphB4 reduced the expression level of Dvl2. Collectively, our results indicate that Dvl2 could be the potential PDZ-domain protein that acts downstream of ephrin B2 in RANKL-induced osteoclast differentiation of RAW264.7 cells, providing a potential novel therapeutic target for bone diseases.

Oxidation of Aluminum Nitride for Defect Characterization

The thermal oxidation of aluminum nitride was developed as a means to study defects in bulk aluminum nitride crystals. The oxidation kinetics was established for the dry oxidation of highly textured AlN polycrystals produced by sublimation-recombination crystal growth in a tungsten furnace. Despite seeding on polycrystalline tungsten, the grains were predominantly [0001] oriented as verified by electron backscattering diffraction (EBSD). The oxidation rate is dependent on the crystal’s orientation, polarity, stress, and surface condition, thus oxidation decorates grain boundaries, polishing scratches, and inversion domains by producing oxide layers of different thicknesses. The initial oxidation rate of nitrogen polar (0001) AlN is approximately 25% faster than on aluminum polar crystals. Low temperature (800 °C) dry oxidation produced an amorphous oxide layer and generated a high density of defects (vacancies, stacking faults, and dislocations) in the nitride near the oxide/nitride interface, as observed by cross-sectional transmission electron microscopy. In contrast, high temperature oxidation (1000 °C) produced a crystalline oxide layer, and left the nitride free of observable defects.

[Progress and prospect in the research of bone morphogenetic protein heterodimer]

Bone morphogenetic protein (BMP) homodimers are of significant osteoinductivity. However, their clinical application is limited because of high effective dosage. Recently, BMP heterodimers are reported to address the issue. This is a review of the researches on BMP heterodimers, including existent evidences, types and synthetic methods, biological activities in comparison to BMP homodimers and possible mechanisms, further research direction and future expectations.

Growth and characterization of ceria thin films and Ce-doped γ-Al2O3 nanowires using sol-gel techniques

γ-Al(2)O(3) is a well known catalyst support. The addition of Ce to γ-Al(2)O(3) is known to beneficially retard the phase transformation of γ-Al(2)O(3) to α-Al(2)O(3) and stabilize the γ-pore structure. In this work, Ce-doped γ-Al(2)O(3) nanowires have been prepared by a novel method employing an anodic aluminium oxide (AAO) template in a 0.01 M cerium nitrate solution, assisted by urea hydrolysis. Calcination at 500 °C for 6 h resulted in the crystallization of the Ce-doped AlOOH gel to form Ce-doped γ-Al(2)O(3) nanowires. Ce(3+) ions within the nanowires were present at a concentration of < 1 at.%. On the template surface, a nanocrystalline CeO(2) thin film was deposited with a cubic fluorite structure and a crystallite size of 6-7 nm. Characterization of the nanowires and thin films was performed using scanning electron microscopy, transmission electron microscopy, electron energy loss spectroscopy, x-ray photoelectron spectroscopy and x-ray diffraction. The nanowire formation mechanism and urea hydrolysis kinetics are discussed in terms of the pH evolution during the reaction. The Ce-doped γ-Al(2)O(3) nanowires are likely to find useful applications in catalysis and this novel method can be exploited further for doping alumina nanowires with other rare earth elements.

Postnatal development of type II collagen and aggrecan mRNA expression in a rabbit craniomandibular joint

The aim of this study was to investigate the postnatal growth changes in the condyle and disc of the rabbit craniomandibular joint (CMJ). Forty-eight rabbits from newborn to an age of 120 days were divided into eight groups, and chondrocytic differentiation and function were evaluated within the CMJ by in situ hybridization of type II collagen and aggrecan mRNA. The morphology of the posterior band and the bilaminar zone were similar in the newborn group and were composed primarily of mesenchymal cells and capillaries. After weaning, mastication loading induced the differentiation of mesenchymal cells, which was accompanied by structural differentiation between the posterior band and the bilaminar zone. Aggrecan first appeared in the posterior band of the disc at 30 days postnatally, when the rabbits began to masticate solid food. Type II collagen emerged in the disc at the age of 45 days. Both genes coexpressed in the deeper half of the proliferative layer, the whole hypertrophic layer, and the mineralized layer of the condylar cartilage and staining intensity increased with age. The coexpression of aggrecan and Type II collagen indicates the maturation of chondrocyte differentiation in the disc and condyle, which contributes to the biomechanical characteristics of the CMJ that resist functional stimulation.