S.G. Zhang

Evidence for Calcifying Nanoparticles in Gingival Crevicular Fluid and Dental Calculus in Periodontitis

BACKGROUND Calcifying nanoparticles (CNPs), also known as nanobacteria, can produce carbonate apatite on their cell walls and initiate pathologic calcification. The objective of this study was to determine whether CNPs are present in the gingival crevicular fluid (GCF) from subjects with periodontal disease and whether they can induce the pathologic calcification of primary cultured human gingival epithelial cells. METHODS GCF and dental calculus samples were collected from 10 subjects with gingivitis and 10 subjects with chronic periodontitis. CNPs in GCF and calculus filtrates were detected with nanocapture enzyme-linked immunosorbent assay kits. The CNPs in cultures of dental calculus filtrates were also identified using immunofluorescence staining, transmission electron microscopy (TEM), and chemical analysis. Pathologic changes in the CNP-treated gingival epithelial cells were observed with TEM, alizarin red staining, and disk-scanning confocal microscopy. RESULTS CNPs were found in GCF samples from two subjects with chronic periodontitis. Based on chemical analysis, the surface-associated material from CNPs isolated and cultured from calculus has a composition similar to dental calculus. The pathologic calcification of CNP-treated gingival epithelial cells was also observed. CONCLUSIONS Self-replicating calcifying nanoparticles can be cultured and identified from dental calculus. This raises the issue of whether CNPs contribute to the pathogenesis of periodontitis.

Superheated liquid fragility and thermodynamic refinement for evaluation of metallic glass-forming ability

Based on the super-Arrhenius equation and Angell’s fragility concept [J. Non-Cryst. Solids 131, 13 (1991)], the expression of the fragility parameter for superheated liquid is deduced as M=E∞∕kBTl, where E∞ is the activation energy, kB the Boltzmann constant, and Tl the liquidus temperature. It exhibits a negative correlation with the glass-forming ability (GFA) of the referenced metallic glasses in the same system rather than in the different systems, while the parameter e based on order-disorder competition is just the opposite. The refined fragility parameter M* (=M∕e) gives a much better reflection of the GFA for the metallic glasses.

rhPDGF-BB Promotes Proliferation and Osteogenic Differentiation of Bone Marrow Stromal Cells from Streptozotocin-Induced Diabetic Rats through ERK Pathway

Management of nonunion fracture and massive segmental bone defects in diabetes remains a challenging clinical problem. Bone marrow stromal cells (BMSCs) are crucial for bone remodeling and hold promise for bone regeneration. However, we have showed previously that diabetes can affect the proliferation and osteogenic potential of BMSCs adversely and a strategy to attenuate the impaired functions of BMSCs is required. Platelet-derived growth factor-BB (PDGF-BB) plays an important role in bone formation. However, little information is available about its effect on diabetic BMSCs. In this study, BMSCs were isolated from streptozotocin-induced diabetic rats. After treatment with recombinant human PDGF-BB (rhPDGF-BB), diabetic BMSCs demonstrated enhanced cell proliferation and osteogenic differentiation based on increased expressions of osteogenic genes (Runx2, alkaline phosphatase, and osteocalcin) and Runx2 protein, as well as upregulated alkaline phosphatase activity and mineralization. Furthermore, blocking extracellular signal regulated kinase (ERK) pathway by inhibitor PD98059 repressed the enhanced proliferation and osteogenic differentiation in diabetic BMSCs induced by rhPDGF-BB. Together, these results indicated that rhPDGF-BB stimulates proliferation and osteogenic differentiation partially through ERK pathway in diabetic BMSCs. Therefore, modulation of diabetic BMSCs could augment BMSCs function affected by diabetes and holds significance for future strategies to treat diabetic bone complications.

Effect of Zn/Gd Ratio on Phase Constitutions in Mg-Zn-Gd Alloys

This paper discusses the influence of Zn/Gd ratio on the phase constitutions of as-cast Mg-Zn-Gd alloys in the Mg-rich corner within the range of 0.5–3.0 at.% for Zn content and 0.5–3.0 at.% for Gd content. The critical Zn/Gd ratio for the formation of icosahedral quasicrystal phase (I phase) and long period stacking ordered (LPSO) structure in the Mg-Zn-Gd system has been confirmed. LPSO structure and (Mg,Zn)3Gd phase are formed in Mg-Zn-Gd alloys in the range of Zn/Gd ratio ≤1.0. However, only (Mg,Zn)3Gd phase is observed in the alloys in the range of 1.0< Zn/Gd ratio <1.5. And if Zn/Gd ratio is ≥1.5, I phase and (Mg,Zn)3Gd phase in the alloys begin to form gradually.

Early loading of splinted implants in the posterior mandible: a prospective multicentre case series.

AIM To evaluate the 12-months clinical and radiological outcomes with the OsseoSpeed(™) TX implant using an early loading protocol in patients with missing teeth in the posterior mandible. MATERIAL AND METHODS Forty-five subjects, with Kennedy class I or II edentulism in the mandible, were enrolled at three centres in China. Two or three implants were placed in one edentulous region using a one-stage procedure. Patients received a screw-retained splinted fixed permanent restoration in one edentulous region 6-8 weeks after surgery. Follow-up took place at 6 and 12 months after loading. Marginal bone level alteration, implant survival and clinical findings were assessed using descriptive statistics. The data were analysed on a patient level, implying that the mean overall implants by patient was used as the statistical unit. The data from the three centres were pooled in the statistical analyses. RESULTS A total of 107 implants were inserted in 45 patients. Twelve months after loading, the implant survival rate was 100%, with a mean (± std) marginal bone gain of 0.08 ± 0.411 mm and healthy soft tissue status. CONCLUSIONS Early loading of splinted OsseoSpeed(™) TX implants was an effective and safe treatment for partial edentulism of the posterior mandible. CLINICAL TRIAL REGISTRATION NUMBER ON CLINICALTRIALS.GOV: NCT01346683.

Uniform Droplets Generation Using a Direct-Mode Jet Pulse Spray System

A novel method of preparation of uniform droplets using a direct-mode jet pulse spray system has been developed. By means of the periodical switch-on between a membrane-like rotating distribution exit and a micronozzle, a fluid stream was stimulated to be disintegrated into monodisperse droplets. The effects of the rotational speed (n) and thickness (H) of the distribution exit and flow rate of the dispersed phase (Q) on droplet characteristics were investigated. It was found that the uniformity of droplets would be enhanced with increased rotational speed and decreased thickness of the distribution exit, even for a relatively high flow rate of the dispersed phase. A relatively steady value of the coefficient of variation in size less than 10% could be obtained under the conditions of n = 350 rpm and H = 3 mm at Q = 7.5–8.7 mL/min. The influence of vortices was characterized by the Taylor number and parameter K, showing that the parameter K is capable of more precisely predicting the turbulence transition. Therefore, the system has effectively attained an improvement not only in uniformity but also in productivity of droplets generation.

Glass Formation and Mechanical Properties of Ti–Cu–Ni Alloys with High Ti Content

A series of Ti–Cu–Ni alloys with Ti content as high as 50–70 at. % expected to possess potential high glass-forming ability (GFA) was designed according to the e criterion (Xia, M. X., Zhang, S. G., Ma, C. L., and Li, J. G., “Evaluation of Glass-Forming Ability for Metallic Glasses Based on Order-Disorder Competition,” Appl. Phys. Lett. Vol. 89, 2006, pp. 091917-1–091917-3) and were prepared by melt spinning and suck casting methods. The samples were examined by X-ray diffractometry, differential scanning calorimetry, optical microscopy, scanning electronic microscopy, and quasistatic compression test. The GFA of the melt-spun ribbons is enhanced with increasing e. Ti58Cu32Ni10 alloy with the maximum designed e value of 0.542 exhibits best GFA with a glass transition temperature of 627 K and a wide supercooled liquid region of 45 K. However, this alloy failed to form a fully glassy rod of 1 mm in diameter. Room temperature compression tests reveal that the 1 mm diameter Ti58Cu32Ni10 glass composite exhibits work-hardening characteristic, with ultimate compressive stress of 2418 MPa, yielding stress σ0.2 of 1448 MPa and about 7.8 % plastic strain. The combination of high strength and ductility was attributed to a dendritic TiCu(Ni) network embedded in the hard glass matrix.