Fabrication,characterization and evaluation of the effect of PLGA and PLGA–PEG biomaterials on the proliferation and neurogenesis potential of human neural SH-SY5Y cells

In recent years with regard to the development of nanotechnology and neural stem cell discovery, the combinatorial therapeutic strategies of neural progenitor cells and appropriate biomaterials have raised the hope for brain regeneration following neurological disorders. This study aimed to explore the proliferation and neurogenic effect of PLGA and PLGA–PEG nanofibers on human SH-SY5Y cells in in vitro condition. Nanofibers of PLGA and PLGA–PEG biomaterials were synthesized and fabricated using electrospinning method. Physicochemical features were examined using HNMR, FT-IR, and water contact angle assays. Ultrastructural morphology, the orientation of nanofibers, cell distribution and attachment were visualized by SEM imaging. Cell survival and proliferation rate were measured. Differentiation capacity was monitored by immunofluorescence staining of Map-2. HNMR, FT-IR assays confirmed the integration of PEG to PLGA backbone. Water contact angel assay showed increasing surface hydrophilicity in PLGA–PEG biomaterial compared to the PLGA substrate. SEM analysis revealed the reduction of PLGA–PEG nanofibers' diameter compared to the PLGA group. Cell attachment was observed in both groups while PLGA–PEG had a superior effect in the promotion of survival rate compared to other groups (p < .05). Compared to the PLGA group, PLGA–PEG increased the number of Ki67⁺ cells (p < .01). PLGA–PEG biomaterial induced neural maturation by increasing protein Map-2 compared to the PLGA scaffold in a three-dimensional culture system. According to our data, structural modification of PLGA with PEG could enhance orientated differentiation and the dynamic growth of neural cells.     

Contribution of the Tyr-1 in Plantaricin149a to Disrupt Phospholipid Model Membranes

Plantaricin149a (Pln149a) is a cationic antimicrobial peptide, which was suggested to cause membrane destabilization via the carpet mechanism. The mode of action proposed to this antimicrobial peptide describes the induction of an amphipathic α-helix from Ala7 to Lys20, while the N-terminus residues remain in a coil conformation after binding. To better investigate this assumption, the purpose of this study was to determine the contributions of the Tyr1 in Pln149a in the binding to model membranes to promote its destabilization. The Tyr to Ser substitution increased the dissociation constant (K_D) of the antimicrobial peptide from the liposomes (approximately three-fold higher), and decreased the enthalpy of binding to anionic vesicles from −17.2 kcal/mol to −10.2 kcal/mol. The peptide adsorption/incorporation into the negatively charged lipid vesicles was less effective with the Tyr1 substitution and peptide Pln149a perturbed the liposome integrity more than the analog, Pln149S. Taken together, the peptide-lipid interactions that govern the Pln149a antimicrobial activity are found not only in the amphipathic helix, but also in the N-terminus residues, which take part in enthalpic contributions due to the allocation at a lipid-aqueous interface.     

Maternal sensitivity during infancy and subsequent life events relate to attachment representation at early adulthood.

A prospective longitudinal research study of 86 prematurely born children from birth to age 18 years provided empirical evidence for continuity from infancy experience to representations of attachment at age 18 years. Young adults whose representation of attachment was dismissing had been objectively observed during infancy, 16–17 years earlier, to receive less sensitive maternal care than those infants who were later judged at early adulthood to have secure or preoccupied representations. Infancy experience alone did not differentiate young adults with secure representations from those with preoccupied representations. Rather, adverse life events through age 12, particularly parental divorce, reduced the likelihood of secure representations and increased the likelihood of preoccupied representations. The absence of adverse life events did not increase the likelihood of security for those who had not experienced early sensitive caregiving. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Langmuir technique and Brewster angle microscope studies of the interfacial behavior of bitumen, asphaltenes and maltenes at the air-water interface. I. Effect of different spreading solution volumes

It is believed that surface active materials in bitumen (asphaltenes and maltenes) are responsible for the stabilization of undesirable water-in-bitumen emulsions in several processes in the petrochemical and oil sands industries. In order to find an efficient technique to break these emulsions, complete knowledge of the interfacial properties of bitumen, maltenes and asphaltenes is required. In this work, the capability of these three fractions to form monolayers at the air-water interface and the structural conformations formed under different compression stages and different added volumes, taken from constant concentration spreading solutions, are analyzed using a Langmuir trough and Brewster angle microscopy. According to the results presented here, the three fractions form true monolayers at the air-water interface with bitumen displaying a “sponge-like” structure, asphaltenes arranging in dense islands and maltenes forming very thin flexible layers. Bitumen, asphaltenes and maltenes organize in association structures of added volume depending sizes: increasing volumes lead to increasing sizes. Compression of the monolayers also favors the formation of larger structures that, upon expansion, do not relax to their original state. This fact is responsible for the hysteresis displayed by the three fractions, being asphaltenes the fraction showing the greatest rigidity, maltenes the greatest flexibility and bitumen an intermediate behavior. Out-of-plane regions were only detected for asphaltenes, which at high surface pressures, fold and bulge up, resulting in a loss of surface active material at the air-water interface. These three-dimensional structures persist upon expansion of the film.     

A fuzzy approach for the earned value management

The Earned Value technique is a crucial technique in analyzing and controlling the performance of a project which allows a more accurate measurement of both the performance and the progress of a project. This paper presents a new fuzzy-based earned value model with the advantage of developing and analyzing the earned value indices, and the time and the cost estimates at completion under uncertainty. As the uncertainty is inherent in real-life activities, the developed model is very useful in evaluating the progress of a project where uncertainty arises. A small example illustrates how the new model can be implemented in reality.     

Electrochemical study of corrosion inhibition of steel reinforcement in alkaline solutions containing phosphates based components

The aim of this study is to investigate the viability of use of sodium phosphate (Na₃PO₄: SP), tetrasodium pyrophosphate (Na₄P₂O₇: TSPP) and hydroxyethylidene-diphosphonic acid (C₂H₈O₇P₂: HEDP) as a non-toxic corrosion inhibitors of steel bars in alkaline media which simulate the electrolyte in the concrete pores. The effectiveness of these phosphate compounds as corrosion inhibitors was investigated by measuring the corrosion potentials, the polarization curves, the corrosion current densities, and the electrochemical impedance spectroscopy of steel bars immersed for 30 days in saturated Ca(OH)₂ solutions with and without chlorides. At the completion of the tests, the mass losses were determined in order to verify the reliability of the electrochemical results. The results showed that phosphate compounds form a protective layer on the steel surface when immersed in alkaline solution without chlorides. In the presence of chloride ions, the SP acts as an anodic inhibitor and reduces the corrosion activity on steel. The HEDP shows lower efficiency, probably due to the decrease of the pH and to the high [Cl⁻]/[inh] ratio used. Results obtained by electrochemical and gravimetric methods are in quite reasonable agreement.     

Surface-Enhanced Raman Scattering (SERS) of Microorganisms

Normal Raman (NR) spectra and surface-enhanced Raman scattering (SERS) spectra were obtained for the bacterium Escherichia coli and were compared with those of two other microorganisms, Haloferax volcanii and Thiobacillus neapolitanus. It was found that at 514 nm the SERS of E. coli was similar to that of flavin adenine dinucleotide (FAD). Upon increasing the excitation wavelength, contributions from other cell components became evident, and they were attributed to nicotinamide adenine dinucleotide (NAD) or other adenine-containing molecules in the bacterium. A comprehensive study of FAD, riboflavin (RF), NAD, and adenine under various experimental conditions was thus performed to shed light on the features in the SERS obtained for E. coli. Comparison of NR and SERS measurements of the various samples enabled a better understanding of the SERS spectra and their sensitivity to the specific experimental conditions (excess metal ion concentration and laser excitation wavelengths and intensity). It was concluded that SERS is a highly sensitive technique and that careful examination of the spectra can provide important chemical information.