Functionalisation of PLLA nanofiber scaffolds using a possible cooperative effect between collagen type I and BMP-2: impact on colonization and bone formation in vivo

The reconstruction of large bone defects after injury or tumor resection often requires the use of bone substitution. Artificial scaffolds based on synthetic biomaterials can overcome disadvantages of autologous bone grafts, like limited availability and donor side morbidity. Among them, scaffolds based on nanofibers offer great advantages. They mimic the extracellular matrix, can be used as a carrier for growth factors and allow the differentiation of human mesenchymal stem cells. Differentiation is triggered by a series of signaling processes, including integrin and bone morphogenetic protein (BMP), which act in a cooperative manner. The aim of this study was to analyze whether these processes can be remodeled in artificial poly-(l)-lactide acid (PLLA) based nanofiber scaffolds in vivo. Electrospun matrices composed of PLLA-collagen type I or BMP-2 incorporated PLLA-collagen type I were implanted in calvarial critical size defects in rats. Cranial CT-scans were taken 4, 8 and 12 weeks after implantation. Specimens obtained after euthanasia were processed for histology and immunostainings on osteocalcin, BMP-2 and Smad5. After implantation the scaffolds were inhomogeneously colonized and cells were only present in wrinkle- or channel-like structures. Ossification was detected only in focal areas of the scaffold. This was independent of whether BMP-2 was incorporated in the scaffold. However, cells that migrated into the scaffold showed an increased ratio of osteocalcin and Smad5 positive cells compared to empty defects. Furthermore, in case of BMP-2 incorporated PLLA-collagen type I scaffolds, 4 weeks after implantation approximately 40?% of the cells stained positive for BMP-2 indicating an autocrine process of the ingrown cells. These findings indicate that a cooperative effect between BMP-2 and collagen type I can be transferred to PLLA nanofibers and furthermore, that this effect is active in vivo. However, this had no effect on bone formation. The reason for this seems to be an unbalanced colonization of the scaffolds with cells, due to insufficient pore size.     

Characterization of copper nanoparticles synthesized by a novel microbiological method

The exploitation of various biomaterials for the biosynthesis of nanoparticles is considered as green technology as it does not involve any harmful chemicals. The present study reports the synthesis of copper nanoparticles which involves non-pathogenic bacterial strain Pseudomonas stutzeri, isolated from soil. These copper nanoparticles are further characterized for size and shape distributions by ultraviolet-visible spectroscopy, x-ray diffraction, and high resolution transmission electron microscopy techniques. The results showed that the particles are spherical and quite stable in nature and shows surface plasmon resonance clearly featured in the optical spectra in visible region.     

Smart secondary polyurethane dispersions

Secondary dispersions of cationic segmented polyurethanes (PUs) with thermoresponsivity (upper critical solution temperature (UCST) in water), high solid contents and antibacterial properties are highlighted in this paper. PUs were prepared by polyaddition reactions and subsequent quaternization with methyl iodide. No additional stabilizers, organic solvents or special procedures were required to obtain stable aqueous dispersions containing up to 10 wt% PU; in contrast, stable dispersions were straightforwardly accessed by a combination of UCST behavior and repulsive electrostatic forces among the positively charged segments, which meets the requirements of a green chemistry process. Particle size and UCST strongly depended on the solid content of the dispersions and the content of poly(ethylene glycol) segments in the copolymers. The dispersions exhibited fast‐acting antibacterial properties against Escherichia coli. © 2013 Society of Chemical Industry     

Clinical Advances in Molecular Biomarkers for Cancer Diagnosis and Therapy

Cancer diagnosis is currently undergoing a paradigm shift with the incorporation of molecular biomarkers as part of routine diagnostic panel. The molecular alteration ranges from those involving the DNA, RNA, microRNAs (miRNAs) and proteins. The miRNAs are recently discovered small non-coding endogenous single-stranded RNAs that critically regulates the development, invasion and metastasis of cancers. They are altered in cancers and have the potential to serve as diagnostic markers for cancer. Moreover, deregulating their activity offers novel cancer therapeutic approaches. The availability of high throughput techniques for the identification of altered cellular molecules allowed their use in cancer diagnosis. Their application to a variety of body specimens from blood to tissues has been helpful for appreciating their use in the clinical context. The development of innovative antibodies for immunohistochemical detection of proteins also assists in diagnosis and risk stratification. Overall, the novel cancer diagnostic tools have extended their application as prognostic risk factors and can be used as targets for personalized medicine.     

Protein modeling and active site binding mode interactions of myrosinase-sinigrin in Brassica juncea--an in silico approach

Myrosinase, the only known S-glycosidase, occurs particularly in Cruciferae family. It is responsible for the hydrolysis of glucosinolates and serves as a vital element of plant defense system. The biological and chemical properties of myrosinase catalyzed products of glucosinolates are well characterized. The myrosinase-protein-sequence of Brassica juncea was retrieved from NCBI database and its 3-D model was generated on the basis of crystal structure of 1MYR-A, 1E4M-M and 1DWA-M chains of myrosinase from Sinapis alba by employing Modeller9v7 program. Homolog templates from S. alba exhibited 72% identity with target sequence. The model was optimized by using molecular dynamics (MD) approach together with simulated annealing (SA) methods in the same Modeller program, and eventually verified and validated on SAVES (Structure Analysis and Verification Server) and PROCHECK programs, respectively. Ramachandran plot obtained through PROCHECK program depicted that 99.8% of total residues were confined to the allowed region while only one residue (Thr92) was restrained to the disallowed region. Additionally, B. juncea myrosinase contains three disulphide bridges which were found to be conserved in S. alba homologs as well. Further, overlapping of B. juncea myrosinase with that of template protein 1MYR-A from S. alba stipulates the amino acid residues Arg115, Gln207, Thr210, Asn350, Tyr352 and Glu429 that constitute active site of the enzyme. Active site analysis also speculates the presence of a hydrophobic pocket in addition to seven N-glycosylation sites. Docking studies of enzyme and substrate illuminate the interactions of various active site residues with diverse groups of sinigrin. Therefore, the present study furnishes the first significant, in silico insight into the 3-D structure, active site machinery, and enzyme-substrate interactions of B. juncea myrosinase.