Toddy Palm (Borassus Flabellifer) Fruit Fibre Bundles as Reinforcement in Polylactide (PLA) Composites: An Overview About Fibre and Composite Characteristics

Toddy palm fruit have an apparent density below 0.8 g/cm³and offer an interesting lightweight construction potential in polylactide(PLA)composites reinforced with 37 mass-%fibres.Single fibre bundles show similar mechanical properties compared with coir:tensile strength of 240 MPa,Young´s modulus of 3.8 GPa and an elongation at break of 31%.However,density and diameter(~50μm)of fruit fibre bundles are significantly lower.The compression moulded composites have a density of 0.9 g/cm³and achieved an unnotched Charpy impact strength of 12 kJ/m^(2),a tensile strength of 25 MPa,Young’s modulus of 1.9 GPa and an elongation at break of 9%.Due to the high porosity of the composites and the different stress-strain behaviour of fibre and matrix the fibre-reinforcement potential could not be fully used.Maximum stress of the composite was reached at the elongation at break of the PLA-matrix(~2%)while the fibre achieved its maximum stress at an elongation of~31%.After reaching the maximum stress of the composite,the fibres were pulled out from the matrix with low energy absorption,resulting in a decrease in stress and a limited reinforcement potential.Additionally,the study investigates whether an insect attack by the Asian fruit fly on the mesocarp has a significant influence on the mechanical fibre characteristics.The results have shown that only the rough surface of the fibre bundles is smoothed by insect infestation.The mechanical properties were not significantly affected.For this reason insect-infested fruits of the toddy palm,which are no longer suitable for food production,can be used for the production of sustainable composite materials.

Biophysical Regulation of Cell Behavior-Cross Talk between Substrate Stiffness and Nanotopography

The stiffness and nanotopographical characteristics of the extracellular matrix （ECM） influence numerous developmental, physiological, and pathological processes in vivo. These biophysical cues have therefore been applied to modulate almost all aspects of cell behavior, from cell adhesion and spreading to proliferation and differentiation. Delineation of the biophysical modulation of cell behavior is critical to the rational design of new biomaterials, implants, and medical devices. The effects of stiffness and topographical cues on cell behavior have previously been reviewed, respectively; however, the interwoven effects of stiffness and nanotopographical cues on cell behavior have not been well described, despite similarities in phenotypic manifestations. Herein, we first review the effects of substrate stiffness and nanotopography on cell behavior, and then focus on intracellular transmission of the biophysical signals from integrins to nucleus. Attempts are made to connect extracellular regulation of cell behavior with the biophysical cues. We then discuss the challenges in dissecting the biophysical regulation of cell behavior and in translating the mechanistic understanding of these cues to tissue engineering and regenerative medicine.

Analysis of the Expression of Angioarchitecture-related Factors in Patients with Cerebral Arteriovenous Malformation

Background： Cerebral arteriovenous malformation （cAVM） is a type of vascular malformation associated with vascular remodeling, hemodynamic imbalance, and inflammation. We detected four angioarchitecture-related cytokines to make a better understanding of the potential aberrant signaling in the pathogenesis of cAVM and found useful proteins in predicting the risk of cerebral hemorrhage. Methods： lmmunohistochemical analysis was conducted on specimens from twenty patients with cAVM diagnosed via magnetic resonance imaging and digital subtraction angiography and twenty primary epilepsy controls using antibodies against vascular endothelial growth factor receptor-2 （VEGFR-2）, matrix metalloproteinase-9 （MMP-9）, vascular cell adhesion molecule （VCAM- 1 ）, and endothelial nitric oxide synthase （eNOS）. Western blotting and real-time fluorescent quantitative polymerase chain reaction （PCR） were performed to determine protein and mRNA expression levels. Student＇s t-test was used for statistical analysis. Results： VEGFR-2, MMP-9, VCAM-1, and eNOS expression levels increased in patients with cAVM compared with those in normal cerebral vascular tissue, as determined by immunohistochemical analysis. In addition, Western blotting and real-time PCR showed that the protein and mRNA expression levels ofVEGFR-2, MMP-9, VCAM-1, and eNOS were higher in the cAVM group than in the control group, all the differences mentioned were statistically significant （P 〈 0,05）. Conclusions： VEGFR-2, MMP-9, VCAM-1, and eNOS are upregulated in patients with cAVM and might play important roles in angiogenesis, vascular remodeling, and migration in patients with cAVM. MMP-9, VEGFR-2, VCAM-1, and eNOS might be potential excellent group proteins in predicting the risk of cerebral hemorrhage at arteriovenous malformation.

Crystal structures of Bbp from Staphylococcus aureus reveal the ligand binding mechanism with Fibrinogen a

Bone sialoprotein-binding protein （Bbp）, a MSCRAMMs （Microbial Surface Components Recognizing Adhesive Matrix Molecules） family protein expressed on the surface of Staphylococcus aureus （S. aureus）, mediates adherence to fibrinogen a （Fg a）, a component in the extracellular matrix of the host cell and is important for infection and pathogenesis. In this study, we solved the crystal structures of apo-Bbp273-598 and Bbp273-598-Fg a561-575 complex at a resolution of 2.03 A and 1.45 A, respectively. Apo-Bbp273-598 contained the ligand binding region N2 and N3 domains, both of which followed a DE variant IgG fold characterized by an additional DI strand in N2 domain and D1＇ and D2＇ strands in N3 domain. The peptide mapped to the Fg o561-575 bond to Bbp273-sgs on the open groove between the N2 and N3 domains. Strikingly, the disordered C-terminus in the apo-form reorganized into a highly-ordered loop and a β-strand G＂ covering the ligand upon ligand binding. BbpAla298-Gly301 in the N2 domain of the Bbp273-598-Fg a561-575 complex, which is a loop in the apo-form, formed a short a-helix to interact tightly with the peptide. In addition, Bbpser547-Glns61 in the N3 domain moved toward the binding groove to make contact directly with the peptide, while BbpAsp338-Gly355 and BbpThr365-Tyr387 in N2 domain shifted their configurations to stabilize the reorganized C-terminus mainly through strong hydrogen bonds. Altogether, our results revealed the molecular basis for Bbp-ligand interaction and advanced our understanding of S. aureus infection process.