A collagen(Col)/nano-hydroxyapatite (nHA) biological composite bone scaffold with double multi-level interface reinforcement

IntroductionBone scaffold is expected to possess excellent mechanical and biological properties similar to natural bone tissues. In this study, we aimed to prepare a biomineralized Col and hydroxyapatite composite scaffold consisting of biomimetic bone components and multi-level bionic bone structure to strengthen its mechanical properties.MethodsWe prepared a Col/nano-hydroxyapatite biological composite scaffold with multi-level structure (from nanofibers to micron bionic bone motif to bionc bone scaffold) of biomimetic bone tissue, and biomineralized the scaffold in simulated body fluid (SBF) preheated to 37 °C. X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and Scanning electron microscope, were used to characterize the biomineralized products.ResultsMorphological study confirmed in situ deposition of nHA in the multi-scale hierarchical structure of the biomineralized scaffold. We explored the biomineralization nucleation mechanism of the scaffolds at the atomic level based on the first principles and the mechanisms for growth of mineralized nHA crystal array in its multi-scale structure, and how the double multiscales structure strengthened the mechanical properties of the material.ConclusionsThis synthetic bone scaffold, with bionic bone composition and double multi-level interface reinforcement, provides a new strategy for synthesizing bioactive bone scaffolds with enhanced biomechanical properties.     

Evaluation of peroxide initiators for radical polymerization‐based self‐healing applications

The suitability of various peroxide initiators for a radical polymerization‐based self‐healing system is evaluated. The initiators are compared using previously established criteria in the design of ring opening metathesis polymerization‐based self‐healing systems. Benzoyl peroxide (BPO) emerges as the best performing initiator across the range of evaluation criteria. Epoxy vinyl ester resin samples prepared with microcapsules containing BPO exhibited upwards of 80% healing efficiency in preliminary tests in which a mixture of acrylic monomers and tertiary amine activator was injected into the crack plane of the sample after the initial fracture. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2698–2708, 2010     

IL-17-deficient allogeneic bone marrow transplantation prevents the induction of collagen-induced arthritis in DBA/1J mice

IL-17-producing CD4⁺ T cells (Th17) play important functions in autoimmune diseases and allograft rejection of solid organs. We examined the effects of IL 17 and its mechanism of action on arthritis in a murine collagen-induced arthritis (CIA) model using bone marrow transplantation (BMT) system. DBA/1J mice were administered a lethal radiation dose and then rescued with bone marrow derived from either wild-type (WT) or IL-17^-/- mice on C57BL/6 background mice. CIA was induced after the bone marrow transplant, and disease progression was characterized. DBA/1J mice with CIA that received IL-17^-/- donor bone marrow showed potently inhibited development and severity of clinical arthritis as compared with CIA mice that received WT bone marrow. Reduced secretion of the pro-inflammatory cytokines tumor necrosis factor-α, IL-1β, and IL-6, and collagen-specific T cell responses were observed in mice that received IL-17^-/- bone marrow. IL-17 blockade also inhibited effector T cell proliferation by reciprocally regulating the Treg/Th17 ratio. IL-17 blockade prevented joint destruction in mice with CIA. These findings suggest that CIA with BMT is a viable method of immunological manipulation and that IL-17 deficiency suppresses severe joint destruction and inflammation in CIA mice. There may be clinical benefits in blocking IL-17 and BMT in the treatment of rheumatoid arthritis.     

环境及遗传因素对温州地区绝经女性骨质疏松影响的研究

为探讨温州地区绝经后女性骨质疏松症（Postmenopausal osteoporosis,PMOP）与雌激素受体基因（Estrogen receptor,ERa）多态性及相关因素的关联性,将203例观察对象按骨质疏松症诊断标准分为骨量正常组、骨量减少组与PMOP组,分别检测各组观察对象的腰椎L1~4正位骨密度、PvuⅡ、XbaⅠ基因型并调查其膳食行为与运动习惯等项目。结果显示：（1）年龄越大、文化程度越低、身材矮小及BMI低者、妊娠次数越多、产次越多者易罹患PMOP;经常饮用牛奶、豆浆、茶,经常食用水产品、豆类、肉类、蛋类、水果、坚果及每月运动次数较多者与高骨密度有关;在校正年龄、文化程度、BMI等干扰因素之后,饮茶、食用水果、坚果类的次数与BMD呈正相关。（2）该研究未发现PvuⅡ与XbaⅠ基因型与PMOP间有关联。提示该地区膳食行为、环境因素与PMOP关系密切,但雌激素受体α多态性与骨密度间关系尚不明确,其对骨质疏松的预测价值尚待深入研究。     

Heterobifunctional Poly(ethylene glycol) Derivatives for the Surface Modification of Gold Nanoparticles Toward Bone Mineral Targeting

Heterobifunctional poly(ethylene glycol)s can be used for many biomedical applications ranging from solubility enhancement of hardly soluble compounds to surface modification of medical devices. In order to modify gold nanoparticles as model particles for drug targeting applications, PEG derivatives are synthesized that possess a high affinity for gold surfaces, namely a thioalkyl function, known to form stable monolayers on gold. Additionally a bisphosphonate function is introduced in the PEG molecule to allow targeting of hydroxyapatite rich tissues, like bone. Gold nanoparticles are modified using the synthesized bifunctional PEG and investigated for their stability in biological fluids and their ability to bind to hydroxyapatite granules in these fluids.

     

Effective PCR detection of animal species in highly processed animal byproducts and compound feeds

In this paper we present a polymerase chain reaction (PCR)-based method for detecting meat and bone meal (MBM) in compound feedingstuffs. By choosing adequate DNA targets from an appropriate localisation in the genome, the real-time PCR method developed here proved to be robust to severe heat treatment of the MBM, showing high sensitivity in the detection of MBM. The method developed here permits the specific detection of processed pig and cattle materials treated at 134 °C in various feed matrices down to a limit of detection of about 0.1%. This technique has also been successfully applied to well-characterised MBM samples heated to as high as 141 °C, as well as to various blind feed samples with very low MBM contents. Finally, the method also passed several official European ring trials.     

Promotion of cell affinity of porous PLLA scaffolds by immobilization of RGD peptides via plasma treatment

In the present work, RGDS (Arg-Gly-Asp-Ser) was immobilized on PLLA scaffolds with plasma treatment. The amount of immobilization, determined by HPLC, was confirmed to be in the effective order. Results from the culture of rat osteosarcoma (ROS), osteoblastic-like cells, demonstrate that the immobilization of RGDS could effectively enhance the attachment of ROS cells on PLLA and increase the cell density in PLLA scaffolds. In addition, experiments of in vitro mineralization indicate that there were more cells and mineralization focci in the RGDS-immobilized scaffolds, suggesting a tendency to form bone-like tissues, compared with the unmodified PLLA scaffold. On the other hand, the PLLA scaffolds immobilized with RGES (Arg-Gly-Glu-Ser) were much less effective in promotion of ROS attachment, suggesting that the enhancement on cell attachment was mainly due to the recognition of RGDS by the adhesion receptors on the cell membrane. The results presented in this work demonstrate that RGDS could be successfully immobilized on PLLA scaffolds with plasma treatment and such modification can make PLLA scaffolds more suitable for culture of osteoblast-like cells and for generation of bone-like tissues.     

Relationships between the anisotropy of longitudinal wave velocity and hydroxyapatite crystallite orientation in bovine cortical bone

Quantitative ultrasound (QUS) is now widely used for evaluating bone in vivo, because obtained ultrasonic wave properties directly reflect the visco-elasticity. Bone tissue is composed of minerals like hydroxyapatite (HAp) and a collagen matrix. HAp crystallites orientation is thus one parameter of bone elasticity. In this study, we experimentally investigated the anisotropy of ultrasonic wave velocity and the HAp crystallites orientation in the axial-radial and axial-tangential planes in detail, using cylindrical specimens obtained from the cortical bone of three bovine femurs. Longitudinal bulk wave propagation was investigated by using a conventional ultrasonic pulse system. We used the one cycle of sinusoidal pulse which was emitted from wide band transmitter. The nominal frequency of the pulse was 1 MHz. First, we investigated the anisotropy of longitudinal wave velocity, measuring the anisotropy of velocity in two planes using cylindrical specimens obtained from identical bone areas. The wave velocity changed due to the rotation angle, showing the maximum value in the direction a little off the bone axis. Moreover, X-ray pole figure measurements also indicated that there were small tilts in the HAp crystallites orientation from the bone axis. The tilt angles were similar to those of the highest velocity direction. There were good correlations between velocity and HAp crystallites orientation obtained in different directions. However, a comparatively low correlation was found in posterior bone areas, which shows the stronger effects of bone microstructure. In the radial-tangential plane, where the HAp crystallites hardly ever align, weak anisotropy of velocity was found which seemed to depend on the bone microstructure.