The influence of patterned nanofiber meshes on human mesenchymal stem cell osteogenesis

A specially designed electroconductive collector enables the electrospinning of P-NFM composed of areas of parallel/uniaxially aligned fibers and areas of random/orthogonal nanofiber distribution. The biological relevance of P-NFM is demonstrated using hBMSCs as an autologous cell source. The structures induce cell orientation along the uniaxially aligned fibers, mainly during earlier culturing periods under basal and osteogenic differentiation conditions. The microtopography of the P-NFM also controls the deposition of mineralized extracellular matrix along the pre-defined fiber direction. Genotypic characterization confirms the successful differentiation into the osteogenic lineage.     

A zebrafish scale assay to monitor dioxin-like activity in surface water samples

New regulations on water quality require a close control of the possible biological activities known or unexpected pollutants may bring about. We present here a protocol based on the direct exposure of zebrafish to river water and the analysis of expression of specific genes in their scales to determine the presence of compounds with dioxin-like biological activity. The method does not require the killing of animals and allows detection of the biological activity after a single day of exposure. When tested, the method with real samples from the Llobregat River, clear temporal and spatial variations were observed, demonstrating its suitability for monitoring natural variations in water quality linked to specific discharges. High biological activities were unrelated to the currently checked water quality parameters (macropollutants, turbidity, TOC, etc.), but they did correlate with the presence of micropollutants (estrogens, detergents, etc.) related to domestic and/or industrial runoffs. The scale assay therefore provides a new tool to evaluate water quality changes that cannot be easily derived from the existing standard analytical procedures. It ranks among the very few described protocols able to detect biological effects from natural water samples, without a pre-concentration step, and after only 24 h of exposure.     

Nanostructure of polysaccharide complexes

The interaction of gum arabic (GA) with chitosan (Ch) of different degree of deacetylation was studied by turbidity measurements, dynamic light scattering and atomic force microscopy. The structure of the complexes was found to be directly related to the charge density of chitosan molecules. Gum arabic and chitosan with a degree of deacetylation of 75% form soluble complexes with a loosely globular structure of about 250 nm, at weight ratios up to 1.2, if the concentrations are kept low (total biopolymer concentration up to 0.06%). If chitosan has a higher charge density (degree of deacetylation of 93%), colloidal particles are formed, independently of the polymer concentration or ratio. At low concentrations and GA/Ch ratios of 1 or 1.2, the particles have diameters of 200-250 nm. The formation of soluble complexes is attributed to a chitosan lower charge density and the presence of non-charged monomers, which prevent the efficient self-assembly of the macromolecules.     

Validation of the ethnopharmacological use of Polygonum persicaria for its antifungal properties

Polygonum L. genus (Polygonaceae) is represented in Argentina by 21 species and some of them have been used in the traditional medicine of our country to treat affections related with fungal infections, such as skin ailments and vaginal diseases. With the aim of contributing to the correct ethnopharmacological use of this genus, in the present work we describe the antifungal properties of P. persicaria (species not studied up to now) and the bio-guided isolation of the main active compounds. Results showed that dichloromethane extracts was the most active with MICs (Minimun Inhibitory Concentrations) between 31.2 - 1000 microg/mL, validating the ethnopharmacological use of P. persicaria to treat affections related with fungal infections in the Argentinean traditional medicine.     

Antimycotic effect of the essential oil of Aloysia triphylla against Candida species obtained from human pathologies

The research of alternative substances to treat infections caused by Candida species is a need. Aromatic plants have the ability to produce secondary metabolites, such as essential oils (EO). The antimicrobial properties of Aloysia triphylla (L'Her.) Britton (cedrón) EO has been previously described. The aims of this work were to determine the antimicrobial activity and the effect on the cell structure of the EO of A. triphylla against Candida sp isolated from human illnesses. The EO was obtained by hydrodistillation of A. triphylla leaves. The minimum inhibitory concentration (MIC) was performed with microdilution method and the minimum fungicidal concentration (MFC) was determined. A. triphylla EO's showed antifungal activity against all yeast: C. albicans, C. dubliniensis, C. glabrata, C. krusei, C. guillermondii, C. parapsilosis and C. tropicalis which were resistant to fluconazol (150 mg/mL). The range of MIC values was from: 35 to 140 microg/mL and the MFC: 1842 to 2300 microg/mL. The time of killing at the MFC against C. albicans (3 x 10(5) UFC/mL) was 140 min. The dates of OD620 and OD260 suggest lysis and loss of absorbing material, respectively. The HROM shows distortion in morphology and shape of the cell, with large vacuoles in the cytoplasm. These studies clearly show that A. triphylla EO is a promising alternative for the treatment of candidiasis.     

On the Ferrers property of valued interval orders

We study the relationship between the Ferrers property and the notion of interval order in the context of valued relations. Given a crisp preference structure without incomparability, the strict preference relation satisfies the Ferrers property if and only if the associated weak preference relation does. These conditions characterize a total interval order. For valued relations the Ferrers property can be written in two different and non-equivalent ways. In this work, we compare these properties by finding the kind of completeness they imply. Moreover, we study whether they still characterize a valued total interval orders.     

A note on classes of structured matrices with elliptical type numerical range

Czechoslovak Mathematical Journal - We identify new classes of structured matrices whose numerical range is of the elliptical type, that is, an elliptical disk or the convex hull of elliptical disks.     

Imposex and organotin body burden in the dog‐whelk (Nucella lapillus L.) along the Portuguese coast

Nucella lapillus imposex—superimposition of male characters onto prosobranch (a subclass of gastropod molluscs) females—and organotin female body burden were surveyed on the Portuguese coast, from Vila Praia de Âncora (northern limit) to Praia da Luz (southern limit), at 17 sampling stations, between May and August 2003. The vas deferens sequence index (VDSI), the relative penis size index (RPSI), the percentage of females affected with imposex (%I) and the percentage of sterile females (%S) were used to assess the level of imposex at each site. VDSI, RPSI and %I were 0.20–4.04, 0.0–42.2% and 16.7–100.0%, respectively. Sterile females were found at stations 2 (6.2%), 5 (4.0%) and 7 (5.0%). Tributyltin (TBT) and dibutyltin (DBT) female body burdens were 23–138 and <10–62 ng Sn/g dry weight, respectively. TBT female body burden was significantly correlated with RPSI and VDSI [Spearman rank order linear correlation: RPSI vs TBT body burden (b.b.) r = 0.71, p < 0.01; VDSI vs logTBT body burden r = 0.71, p < 0.01]. Imposex and TBT b.b. were highest at sites located in the proximity of harbours, where TBT leaching from antifouling paints is more intense owing to the high concentration of ships and dockyard activities. Copyright © 2005 John Wiley & Sons, Ltd.     

THE EFFECT OF ALA AND RADIATION ON PORPHYRIN/HEME BIOSYNTHESIS IN ENDOTHELIAL CELLS

To study porphyrin biosynthesis in human microvascular endothelial cells, HMEC-1 cells, a transformed human microvascular endothelial cell line, were incubated with 5-aminolevulinic acid (ALA), the precursor of endogenous porphyrins, and porphyrin accumulation was measured spectro-fluorometrically. The HMEC-1 cells accumulated porphyrin in a concentration-related and a time-dependent fashion. Protoporphyrin was the predominant porphyrin accumulated in the cells. The effect of light on protoporphyrin accumulation was evaluated by exposing the ALA-loaded HMEC-1 cells to ultraviolet-A (UVA) and blue light, followed by another incubation with ALA for 2–24 h. Enhancement of protoporphyrin accumulation in irradiated HMEC-1 cells was observed 2–24 h after irradiation, which was associated with a decrease in ferrochelatase protein and activity. Porphyrin accumulation from ALA after irradiation was significantly decreased when catalase (750–3000 U/mL, 29.3–44.3% suppression) or superoxide dismutase (270 U/mL, 36.4% suppression) was present during irradiation. These data demonstrate that HMEC-1 cells were capable of porphyrin biosynthesis, and that exposure of protoporphyrin-containing HMEC-1 cells to UVA and blue light, which includes the Soret band spectrum, decreased the ferrochelatase activity and its protein. These changes were mediated, at least in part, by reactive oxygen species.     

Numerical Method to Fit the Refractive Index Profile of Planar Microlenses Made by Ion Exchange Techniques

We present a fitting method for obtaining a functional form of the refractive index profile of planar microlenses made by ion exchange techniques from total shearing interferometric measurements. Compared to the usual power series expansion fit, this method allows a reduction in the number of coefficients needed to characterize a lens.