Biomedical subjects

P Medberry

Publications and source records attributed to P Medberry.

3 recordsLinked to original sources

PubMed2004

pDNA bioparticles: comparative heterogeneity, surface, binding, and activity analyses.

New applications for nucleic acid-bound micro/nanoparticles are emerging in drug delivery, biocatalysis, diagnostics, and toxicology. Bioactivity of viral or liposomal based technologies is limited by heterogeneity, partitioning, aggregation, and protein binding in physiological fluids, underlying immunotoxicity, and poor in vitro and cell-culture corollaries. Here we have systematically investigated novel pDNA bioparticles formed through complexation to model non-viral/non-lipid materials, peptides, aminoglycans, and small molecules (polybrene, chitosan, butirosin, protamine, Lys10, RGDS, bupivacaine, and chlorpromazine). On the basis of characterization by heterogeneity, kinetics, partitioning in physiological fluid and serum protein-binding, surface, size and electrophoretic behavior, transfection, and immunotoxicity, notably protamine, and chitosan DNA particles gave a long lifetime (12-18h), low protein-binding (<10microg/ml), good transfection activity (10(2)-10(4)RLU/mg cell protein), and low immunotoxicity. Our results support further evaluation of these materials as potential alternatives to viral or liposomal approaches, in combination with pDNA as binding, expression or therapeutic agents.

Animals↗

PubMed1997

Inducible nitric-oxide synthase and nitric oxide production in human fetal astrocytes and microglia. A kinetic analysis.

The understanding of the induction and regulation of inducible nitric-oxide synthase (iNOS) in human cells may be important in developing therapeutic interventions for inflammatory diseases. In the present study, we not only demonstrated that human fetal mixed glial cultures, as well as enriched microglial cultures, synthesize iNOS and nitric oxide (NO) in response to cytokine stimulation, but also assessed the kinetics of iNOS and NO synthesis in human fetal mixed glial cultures. The iNOS mRNA was expressed within 2 h after stimulation and decreased to base line by 2 days. Significant levels of iNOS protein appeared within 24 h after stimulation and remained elevated during the culture period. A dramatic increase in NO production and NO-mediated events, such as the induction of cyclic guanosine monophosphate (cGMP), NADPH diaphorase activity, and nitrotyrosine occurred 3 days after stimulation, a delay of 48 h from the time of the first expression of iNOS enzyme. This delay of NO production was altered by the addition of tetrahydrobiopterin, but not by the addition of L-arginine, heme, flavin adenine dinucleotide (FAD), flavin mononucleotide (FMN), or NADPH. These findings suggest that a post-translational regulatory event might be involved in iNOS-mediated NO production in human glia.

Astrocytes↗

PubMed1997

Quantitative measurement for endothelial constitutive nitric oxide synthase in cultured human endothelial cells.

Constitutively expressed endothelial nitric oxide synthase (ecNOS) produces nitric oxide (NO) from L-arginine and is important for the maintenance of cardiovascular homeostasis. We report the development of a capture ELISA which is specific for ecNOS. The assay detection limit is 0.5 ng/ml ecNOS protein, allowing the measurement of ecNOS from as few as 6000 human endothelial cells cultured in 96-well microtiter plates. This ELISA has been used to measure a downregulation of ecNOS with 24-h TNFalpha treatment, consistent with results obtained by Western blot analysis. Quantitation of ecNOS in human endothelial cells showed a higher expression of ecNOS in human aortic endothelial cells (18.3+/-1.35 ng ecNOS per 10(6) cells, n = 3 donors) than in human umbilical vein endothelial cells (10.4+/-0.48 ng ecNOS per 10(6) cells, n = 3 donors). These studies demonstrate that this convenient, quantitative assay is currently the most sensitive method for investigating ecNOS protein regulation.

Amino Acid Sequence↗