Antibacterial Activity of Defensin PaDef from Avocado Fruit (Persea americanavar.drymifolia) Expressed in Endothelial Cells againstEscherichia coliandStaphylococcus aureus

Antimicrobial therapy is a useful tool to control infectious diseases in general and rising antibiotic resistant microorganisms in particular. Alternative strategies are desirable, and antimicrobial peptides (AMP) represent attractive control agents. Mexican avocado (Persea americanavar.drymifolia) is used in traditional medicine; however, the AMP production has not been reported in this plant. We obtained a cDNA library from avocado fruit and clone PaDef was identified, which has a cDNA (249 bp) encoding a protein (78 aa) homologous with plant defensins (>80%). We expressed the defensinPaDefcDNA (pBME3) in the bovine endothelial cell line BVE-E6E7. Polyclonal and clonal populations were obtained and their activity was evaluated againstEscherichia coli,Staphylococcus aureus, andCandida albicans.E. coliviability was inhibited with 100 μg/mL of total protein from clones (>55%). Also,S. aureusviability was inhibited from 50 μg/mL total protein (27–38%) but was more evident at 100 μg/mL (52–65%). This inhibition was higher than the effect showed by polyclonal population (~23%). Finally, we did not detect activity againstC. albicans. These results are the first report that shows antimicrobial activity of a defensin produced by avocado and suggest that this AMP could be used in the control of pathogens.

Investigation of the Influences of Micro Vibrational Stimuli and Hydrophilicity of a Scaffold on a Bovine Endothelial Cell Culture

Both the hydrophilicity of the scaffold and applied sheer stress can influence the growth of cultured cells. In this study, the influences of applied shear stress and the hydrophilicity of the scaffold on the growth of bovine endothelial cells (BEC) were investigated. A piezoelectric micro vibrational stage was used to provide micro vibrational stimuli of different frequencies to generate various sheer stresses. 24-well, biodegradable lactide-co-glycolide (PLGA) scaffolds, and nanostructuresd PLGA scaffolds were used for the cell culturing. From the results of this study, it can be inferred that the vibration induced sheer stress can effectively enhance BEC growth as long as the corresponding sheer force is less than the adhesive force between a cell and the scaffold. It is also suggested that micro vibration stimulus may be a more cost and time effective solution than the nanostructured scaffold approach for the enhancement of BEC growth.

Adhesion Studies of Single Living Cells Using MEMS Sensors

Adhesion between cells is related to several physiological phenomena such as heart failure (Karila00), how cancer spreads (Ruoslahti99) and if an infection will be fought off. Controlling of these events requires knowledge of how cells adhere. Many previous studies have been conducted with various amounts of success. But none of these methods are independently capable of understanding the adhesion properties of a single living cell. In this article a MEMS sensor has been employed to study, quantitatively and qualitatively, the adhesion properties of a single living bovine endothelial cell. This experiment shows that the strength of a single anchorage site of the endothelial cell to an extracellular matrix coated substrate is 36 nN. Anchorage sites have been observed, in-situ, to be spaced on the order of 1 μm intervals. A model is also proposed for the detachment of a single living cell from a substrate.

Monoclonal Antibody Binding to a Surface-Exposed Epitope on Cowdria ruminantium That Is Conserved among Eight Strains

ABSTRACT Monoclonal antibodies (MAb) binding to Cowdria ruminantium elementary bodies (EB) were identified by enzyme-linked immunosorbent assay, and surface binding of one MAb (446.15) to intact EB was determined by immunofluorescence, immunogold labeling, and transmission electron microscopy. MAb 446.15 bound an antigen of approximately 43 kDa in immunoblots of eight geographically distinct strains. The MAb did not react with Ehrlichia canis antigens or uninfected bovine endothelial cell lysate and may be useful in diagnostic assays and vaccine development.