pH responsive biomineralization onto chitosan grafted biodegradable substrates

Bioactive composites that enable the formation of an apatite layer onto the surface are important in the development of osteoconductive biomaterials in orthopaedic applications. In this work, the surface of biodegradable and bioactive substrates, composed of poly(L-lactic acid) (PLLA) reinforced with Bioglass , was modified by coupling chitosan to the surface, using plasma activation. The wettability of the modified films was analysed by contact angle (CA) measurements as a function of pH. It was found that this surface property changed significantly with pH. Moreover, the apatite formation on the surface upon immersion of the modified films in a simulated body fluid (SBF) solution was analysed at pH 5.4 and pH 7.4 by scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS). It was found that such modification, together with the effect of pH, could block the formation of apatite onto the biodegradable substrate upon immersion in a simulated body fluid solution when the pH changed to 5.4. On the other hand, a dense apatite layer was formed at pH 7.4. For the unmodified substrates an apatite layer was formed at both pHs. These results suggest that the formation of apatite or possibly other kinds of minerals could be controlled by such a smart surface, in this case pH-responsive

Effect of The Inclusion of Butterfly Pea (Clitoria ternatea) and Green Sea Weed (Ulva lactuca) in The Complete Feed on The Concentration of Blood Metabolites of Male Kacang Goats

This experiment aimed to investigate the effect of including  Clitoria ternatea and Ulva lactuca in the complete feed on the concentration of blood metabolites of male kacang goats. Four male kacang goats were involved in this experiment arranged following a Latin Square Design with 4 treatments and 4 periods as replication. The treatments were R0= native grass hay 60%+concentrate 40%, R1= native grass hay 30%+concentrate 40%+ Clitoria ternatea 30%, R2= native grass hay 30%+concentrate 40%+ Clitoria ternatea 15%+ Ulva lactuca 15% and R3= native grass hay 30%+ concentrate 40%+Ulva lactuca 30%. Data were analyzed using analysis of variance (ANOVA) and followed by the Duncan Multiple Range Test when significant differences were found. The results showed that  feeding a complete feed containing  Clitoria ternatea and Ulva lactuca did not significantly (P>0,05) affect the concentration of urea, glucose and  plasm total protein in the blood of male kacang goats. Therefore, it can be concluded the inclusion of Clitoria ternatea and Ulva lactuca has no effect on the concentration of blood metabolites in male kacang goats

Designing biomaterials based on biomineralization of bone

In nature, organisms control crystal nucleation and growth using organic interfaces as templates. Scientists, in the last decades, have tried to learn from nature how to design biomimetic biomaterials inspired by the hierarchical complex structure of bone and other natural mineralised tissues or to control the biomineralization process onto biomaterials substrates to promote the osteoconductive properties of implantable devices. The design of synthetic bone analogues, i.e., with a structure and properties similar to bone, would certainly constitute a major breakthrough in bone tissue engineering. Moreover, many strategies have been proposed in the literature to develop bioactive bone-like materials, for instance using bioactive glasses. Fundamental aspects of biomineralization may be also important in order to propose new methodologies to improve calcification onto the surface of biomaterials or to develop bioactive tridimensional templates that could be used in regenerative medicine. In particular, it has been shown that some chemical groups and proteins, as well as the tridimensional matrix in which calcification would occur, play a fundamental role on the nucleation and growth of hydroxyapatite. All these distinct aspects will be reviewed and discussed in this paper.I. B. Leonor thanks the Portuguese Foundation for Science and Technology (FCT) for providing her a post-doctoral scholarship (SFRH/BPD/26648/2006). This work was supported by the European NoE EXPERTISSUES (NMP3-CT-2004-500283) and by the Portuguese Foundation for Science and Technology, FCT, through the projects PTDC/CTM/68804/2006, PTDC/CTM/67560/2006 and PTDC/FIS/68209/2006

Magnetic-responsive hydrogels for cartilage tissue engineering

Publicado em "Journal of Tissue Engineering and Regenerative Medicine", vol. 7, supp. 1 (2013)The use of magnetic nanoparticles (MNPs) has been explored as an alternative approach to overcome current limitations of regenerative medicine strategies. Cell engineering approaches where MNPs are incorporated within three-dimensional constructs, such as scaffolds or hydrogels may constitute a novel and attractive approach towards the development of a magnetically-responsive system. These systems would enable remote controlled actions over tissue engineered constructs in vitro and in vivo. Moreover, growing evidence suggests that the application of a magnetic field may enhance biological performance over commonly used static culture conditions providing stimulation for cell proliferation, migration and differentiation. In this work we analyze the role of magnetic stimulation on the behavior of human adipose derived stem cells (hASCs) laden in k-carrageenan hydrogels aiming at cartilage tissue engineering approaches. Thermo-responsive natural-based κ-carrageenan hydrogels were used as 3D templates since previous studies(1) report the adequate environment provided by these materials to support the viability and chondrogenic differentiation of several types of cells

Development of a simultaneous analytical method for five conjugated cholesterol metabolites in urine and investigation of their performance as diagnostic markers for Niemann-Pick disease type C

Niemann-Pick disease type C (NPC) is an autosomal recessive disorder characterized by progressive nervous degeneration. Because of the diversity of clinical symptoms and onset age, the diagnosis of this disease is difficult. Therefore, biomarker tests have attracted significant attention for earlier diagnostics. In this study, we developed a simultaneous analysis method for five urinary conjugated cholesterol metabolites, which are potential diagnostic biomarkers for a rapid, convenient, and noninvasive chemical diagnosis, using liquid chromatography/tandem mass spectrometry (LC/MS/MS). By the method, their urinary concentrations were quantified and the NPC diagnostic performances were evaluated. The developed LC/MS/MS method showed high accuracy and and satisfied all analytical method validation criteria. Analyzing the urine of healthy controls and patients with NPC, three of five urinary conjugated cholesterol metabolites concentrations corrected by urinary creatinine were significantly higher in the patients with NPC. As a result of receiver operating characteristics analysis, the urinary metabolites might have excellent diagnostic marker performance. 3β-sulfooxy-7β-hydroxy-5-cholenoic acid showed particularly excellent diagnostic performance with both 100% clinical sensitivity and specificity, suggesting that it is a useful NPC diagnostic marker. The urinary conjugated cholesterol metabolites exhibited high NPC diagnostic marker performance and could be used for NPC diagnosis

Electromagnetic waves in NUT space: Solutions to the Maxwell equations

In this paper, using the Newman-Penrose formalism, we find the Maxwell equations in NUT space and after separation into angular and radial components solve them analytically. All the angular equations are solved in terms of Jaccobi polynomials. The radial equations are transformed into Hypergeometric and Heun's equations with the right hand sides including terms of different order in the frequency of the perturbation which allow solutions in the expansion of this parameter.Comment: 19 pages, Revtex format, Minor changes including an extention of the discussion and typos correction, (Extended version of the article presented to the GR16 conference, July 15-21 2001, Durban, South Africa

Variational Worldline Approximation for the Relativistic Two-Body Bound State in a Scalar Model

We use the worldline representation of field theory together with a variational approximation to determine the lowest bound state in the scalar Wick-Cutkosky model where two equal-mass constituents interact via the exchange of mesons. Self-energy and vertex corrections are included approximately in a consistent way as well as crossed diagrams. Only vacuum-polarization effects of the heavy particles are neglected. In a path integral description of an appropriate current-current correlator an effective, retarded action is obtained by integrating out the meson field. As in the polaron problem we employ a quadratic trial action with variational functions to describe retardation and binding effects through multiple meson exchange.The variational equations for these functions are derived, discussed qualitatively and solved numerically. We compare our results with the ones from traditional approaches based on the Bethe-Salpeter equation and find an enhanced binding contrary to some claims in the literature. For weak coupling this is worked out analytically and compared with results from effective field theories. However, the well-known instability of the model, which usually is ignored, now appears at smaller coupling constants than in the one-body case and even when self-energy and vertex corrections are turned off. This induced instability is investigated analytically and the width of the bound state above the critical coupling is estimated.Comment: 62 pages, 7 figures, FBS style, published versio

Entropy of a Kerr-de Sitter black hole due to arbitrary spin fields

The Newman-Penrose formalism is used to derive the Teukolsky master equations controlling massless scalar, neutrino, electromagnetic, gravitino, and gravitational field perturbations of the Kerr-de Sitter spacetime. Then the quantum entropy of a non-extreme Kerr-de Sitter black hole due to arbitrary spin fields is calculated by the improved thin-layer brick wall model. It is shown that the subleading order contribution to the entropy is dependent on the square of the spins of particles and that of the specific angular momentum of black holes as well as the cosmological constant. The logarithmic correction of the spins of particles to the entropy relies on the rotation of the black hole and the effect of the cosmological constant.Comment: 28 pages, two figures, Revtex4.0. Final revised version to appear in PR

Consequences of Kaizen Practices in MSMEs in the Philippines: The Case of the Manufacturing Productivity Extension Program (MPEX)

The Manufacturing Productivity Extension Program (MPEX) is a fully subsidized public-instigated productivity improvement program directed toward the micro, small, and medium enterprise (MSME) sector. While not advertised and packaged as a Kaizen initiative, it has all the elements of the Kaizen philosophy. Based on survey responses from 64 MPEX beneficiaries and 47 non-MPEX beneficiaries, the study showed that MPEX increased the number of product lines implying that Kaizen practice leads to product innovation among firms. Due to data and confounding issues, significant difference in productivity in terms of number of workers and sales per worker was not established. Firm asset size was implied to influence the capability to implement Kaizen. Regulatory compliance and customer demand requirements and entrepreneurial capacity are catalysts for enabling, adopting, and sustaining Kaizen implementation