A Parallel plate electrostatic droplet generator: Parameters affecting microbead size

Polymer microbead production by parallel plate electrostatic extrusion is presented. Factors affecting microbead size such as needle gauge, electrostatic potential, distance between needle and collecting solution, and polymer solution concentration and flow rate were evaluated. Smaller microbeads resulted from reduced needle diameter, reduced needle to collecting solution distance, increased electrostatic potential, and reduced polymer solution concentration and flow rate. In terms of process scale-up, it was shown that a multi-needle (20) device could continuously produce relatively uniform beads via electrostatics. The technology was demonstrated to be feasible for cell encapsulation or immobilization as there was no detectable effect of applied potential onSpodoptera frugiperda viability.     

An evaluation of three methods for the measurement of diamine oxidase (DAO) activity in amniotic fluid.

The activity of diamine oxidase (DAO) in amniotic fluid was measured by three different methods. The first two, one colorimetric and the other fluorometric, depended on the coupled peroxidase assay. The other was a radiochemical procedure. The latter proved to be a reliable method, free from interference and linear over a wide range of time and substrate concentration. The coupled peroxidase assay was shown to be affected by a variety of factors. It was not linear with time, owing to a lag period that varied from sample to sample. The hydrogen peroxide-peroxidase reaction was inhibited by high substrate concentrations and by undialyzed amniotic fluid.     

Sequence-specific binding of HMG-I(Y) to the proximal promoter of the gp91-phox gene.

Screening of a cDNA expression library with a CCAAT-box element derived from the myelomonocyte-specific gp91-phox promoter resulted in the isolation of three independent HMG-I(Y) cDNA clones. Filter binding competition studies reveal that HMG-Y binds to this promoter element in a sequence-specific manner and exhibits a gradient of binding affinities for various A/T-rich sequences. Two adjacent A/T-rich regions within the gp91-phox promoter CCAAT-box element are required for maximal binding. In addition, competition experiments demonstrate that the binding affinity of HMG-Y is influenced by sequences that flank A/T-rich core binding sites.