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Atlanta, GA, United States

Lee K.N.,Poxvirus and Rabies Branch | Lee K.N.,Mercer University | Ye Y.,Biotechnology Core Facility Branch | Carr J.H.,Clinical and Environmental Microbiology Branch | And 2 more authors.
Journal of Microencapsulation | Year: 2011

Albumin microparticles containing Ofloxacin (Fluoroquinolone derivative commonly used in hospitals) were formulated by the spray dry method. By decreasing the pump feed rate or the total polymer concentration, a mixture of albumin/hypromellose acetate succinate (HPMCAS) microparticles and nanoparticles (MP/NP), containing Ofloxacin, were formulated. MP/NP were characterized, in vitro (particle size, zeta potential, and encapsulation efficiency). A comparison of the pharmacokinetics and biodistribution of aqueous Ofloxacin and Ofloxacin-loaded MP/NP, in Balb/c mice, revealed that peak concentrations were reduced in the serum, liver, spleen and brain, and a more sustained release was observed in serum and all of the organs tested for Ofloxacin MP/NP, compared to aqueous Ofloxacin. The MP/NP formulation allowed extended release by 24?h in the liver and more than 48?h in the brain. In serum, the elimination rate of Ofloxacin MP/NP is slower, the half life is longer, area under the plasma concentration time curve is decreased and volume of distribution is increased. © 2011 Informa UK Ltd All rights reserved. Source


Harris C.,University of Michigan | Shuster D.Z.,University of Michigan | Gomez R.R.,University of Michigan | Sant K.E.,University of Michigan | And 3 more authors.
Free Radical Biology and Medicine | Year: 2013

Developmental signals that control growth and differentiation are regulated by environmental factors that generate reactive oxygen species (ROS) and alter steady-state redox environments in tissues and fluids. Protein thiols are selectively oxidized and reduced in distinct spatial and temporal patterns in conjunction with changes in glutathione/glutathione disulfide (GSH/GSSG) and cysteine/cystine (Cys/ CySS) redox potentials (Eh) to regulate developmental signaling. The purpose of this study was to measure compartment-specific thiol redox status in cultured organogenesis-stage rat conceptuses and to evaluate the impact of thiol oxidation on the redox proteome. The visceral yolk sac (VYS) has the highest initial (0 h) total intracellular GSH (GSH+2GSSG) concentration (5.5 mM) and the lowest Eh (-223 mV) as determined by HPLC analysis. Total embryo (EMB) GSH concentrations ranged lower (3.2 mM) and were only slightly more oxidized than the VYS. Total GSH concentrations in yolk sac fluid (YSF) and amniotic fluid (AF) are >500-fold lower than in tissues and are highly oxidized (YSF Eh=-121 mV and AF Eh=-49 mV). Steady-state total Cys concentrations (Cys+2CySS) were significantly lower than GSH in tissues but were otherwise equal in VYS and EMB near 0.5 mM. On gestational day 11, total GSH and Cys concentrations in EMB and VYS increase significantly over the 6 h time course while Eh remains relatively constant. The Eh (GSH/GSSG) in YSF and AF become more reduced over time while Eh (Cys/CySS) become more oxidized. Addition of L-buthionine-S,R-sulfoximine (BS0) to selectively inhibit GSH synthesis and mimic the effects of some GSH-depleting environmental chemicals significantly decreased VYS and EMB GSH and Cys concentrations and increased Eh over the 6 h exposure period, showing a greater overall oxidation. In the YSF, BSO caused a significant increase in total Cys concentrations to 1.7 mM but did not significantly change the Eh for Cys/CySS. A significant net oxidation was seen in the BSO-treated AF compartment after 6 h. Biotinylated iodoacetamide (BIAM) labeling of proteins revealed the significant thiol oxidation of many EMB proteins following BSO treatment. Quantitative changes in the thiol proteome, associated with developmentally relevant pathways, were detected using isotope coded affinity tag (ICAT) labeling and mass spectroscopy. Adaptive pathways were selectively enriched with increased concentrations of proteins involved in mRNA processing (splicesome) and mRNA stabilization (glycolysis, GAPDH), as well as protein synthesis (aminoacyl-tRNA) and protein folding (antigen processing, Hsp70, protein disulfide isomerase). These results show the ability of chemical and environmental modulators to selectively alter compartmental intracellular and extracellular GSH and Cys concentrations and change their corresponding Eh within the intact viable conceptus. The altered Eh were also of sufficient magnitude to alter the redox proteome and change relative protein concentrations, suggesting that the mechanistic links through which environmental factors inform and regulate developmental signaling pathways may be discovered using systems developmental biology techniques. © 2013 Elsevier Inc. All rights reserved. Source


Harris C.,University of Michigan | Jilek J.L.,University of Michigan | Sant K.E.,University of Michigan | Pohl J.,Biotechnology Core Facility Branch | And 2 more authors.
Journal of Nutritional Biochemistry | Year: 2015

The process of embryonic nutrition in rodent conceptuses during organogenesis has been shown to involve a dominant histiotrophic mechanism where essential developmental substrates and micronutrients are supplied as whole maternal proteins or cargoes associated with proteins. The histiotrophic nutrition pathways (HNP) responsible for uptake and initial processing of proteins across maternal-conceptal interfaces involve uptake via receptor mediated endocytosis and protein degradation via lysosomal proteolysis. Chemical inhibition of either process can lead to growth deficits and malformation in the embryo (EMB), but selective inhibition of either HNP component will elicit a different subset of developmental perturbations. In vitro, whole embryo culture exposure of GD10 or GD11 rat conceptuses to the natural protease inhibitor, leupeptin, leads to significant reductions in all measured embryonic growth parameters as well as a myriad of other effects. Leupeptin doses of 10 μM or 20 μM over a 26-h period (GD10-GD11) and 50 μM over a 3 h pulse period produced significant decreases in the clearance of FITC-albumin from culture media. The near complete loss of acid soluble fluorescence and increased total visceral yolk sac (VYS) protein content confirmed the selective inhibition of proteolysis. Inhibition of lysosomal proteolysis thus deprives the developing EMB of essential nutrient amino acids producing conditions akin to amino acid starvation, but may also cause direct effects on pathways critical for normal growth and differentiation. Following leupeptin exposure for 26 or 6 h, total glutathione (GSH) concentrations dropped significantly in the VYS, but only slightly in yolk sac (YSF) and amniotic (AF) fluids. Cys concentrations increased in VYS and EMB, but dropped in YSF and AF fluids. Redox potentials (E. h) for the glutathione disulfide (GSSG)/glutathione (GSH) redox couple trended significantly toward the positive, confirming the net oxidation of conceptual tissues following leupeptin treatment. Analysis of the thiol proteome showed few alterations to specific pathways mapped to the Kyoto Encyclopedia of Genes and Genomes Pathway database, but did reveal significant increases in concentrations of proteins associated with glycolysis/gluconeogenesis in the VYS and decreased concentrations proteins associated with ribosome biogenesis and function in the EMB. A subset of proteins elevated by >2-23-fold in the VYS were identified as serum (blood) proteins and represent the maternal-side proteins captured by the VYS and which are not degraded in the lysosomes as a result of leupeptin's inhibitory action. The observed constellation of proteins decreased in the EMB by leupeptin represent proteins from several adaptive pathways that are commonly altered in responses to amino acid starvation. These studies show clear differential responses to protease inhibition in VYS and EMB during organogenesis and suggest the possibility for additional roles of redox regulation, cellular adaptations and metabolic insufficiency caused by protease inhibition. © 2015 Elsevier Inc.. Source

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