Level of Evidence: 1b Laryngoscope

Objectives: Single doses of different ototopical antibiotic preparations (OAPs) have been shown to have an unequal reduction of post tympanostomy tube otorrhea (PTTO). Microbial biofilm formation on the tympanostomy tube (TT) has been implicated as one cause of PTTO. The goal of this study was to determine if TT exposure to a single dose of OAP reduces biofilm formation by Pseudomonas aeruginosa. Study Design: Prospective and controlled. Methods: Fluoroplastic TTs were briefly exposed to plasma, followed by one of three OAPs (ofloxacin, neomycin/polymyxin B/hydrocortisone, or ciprofloxacin/dexamethasone) or saline (20 TT per group). TTs were placed in growth media with P. aeruginosa and incubated for 4 days, during which total bacterial growth was monitored by media turbidity. At 4 days, planktonic organisms were killed and biofilm development was measured with microbial counts. Results: Bacterial growth was significantly delayed by OAPs, with the least growth seen with ciprofloxacin/dexamethasone followed by ofloxacin and neomycin/polymyxin B/hydrocortisone (P .0001). At day 4, bacterial growth was less with ciprofloxacin/dexamethasone than ofloxacin and neomycin/polymyxin B/hydrocortisone (P < .05). After 4 days, biofilm counts were lower on OAP-treated than saline-treated TTs (P ¼ .0015) with both ciprofloxacin/dexamethasone and ofloxacin significantly less than saline (P < .05). Biofilm counts were not significantly different between OAPs (P > .05). Conclusions: Treatment of TTs with ototopical antibiotic preparations reduces P. aeruginosa growth and biofilm formation in vitro. This may, in part, explain the reduction of PTTO rates observed with single doses of OAPs

Association of Mitochondrial Function and Feed Efficiency

Studies were conducted to evaluate the potential link between mitochondrial function and biochemistry with the phenotypic expression of feed efficiency (FE) in a single line of broilers fed the same diet. Mitochondria isolated from low FE birds had lower respiratory chain coupling but oxidative phosphorylation capability was either equal or superior to that of mitochondria from broilers with high FE. Higher H2O2 production and higher protein carbonyls (oxidation) was also consistently observed in mitochondria or homogenate from low FE broilers. Respiratory chain complex activities, except for Complex IV activity in the duodenum, were lower in mitochondria from low FE birds. There were differences in gene and protein expression of certain mitochondrial and extra-mitochondrial proteins, but there was no indication that the lower complex activity and respiratory chain coupling in mitochondria from low FE birds is due to a generalized decreased in gene or protein expression. However, three mitochondrial proteins (COX II, cyt c1, and cyt c) and vinculin, a focal adhesion regulator, appear to be differentially expressed with broiler FE phenotype in several tissues. To our knowledge, these studies are the first to demonstrate functional and biochemical differences in mitochondria isolated from tissues of broilers with low and high FE. Furthermore, differences in expression of mitochondrial proteins between high and low FE birds could be exploited to develop FE biomarker(s) to aid selection programs in identifying breeder replacement stock with inferior or superior FE

AAV3-Mediated Transfer and Expression of the Pyruvate Dehydrogenase E1 Alpha Subunit Gene Causes Metabolic Remodeling and Apoptosis of Human Liver Cancer Cells

Most cancers rely disproportionately on glycolysis for energy even in the presence of adequate oxygen supply, a condition known as aerobic glycolysis , or the Warburg effect. Pharmacological reversal of the Warburg effect has been shown to cause selective apoptosis of tumor cells, presumably by stimulating mitochondrial respiratory chain activity and production of reactive oxygen species that, in turn, induce a caspase-mediated series of reactions leading to cell death. We reasoned that a similar effect on tumor cells might result from up-regulation of the E1α subunit gene (pda1) of the pyruvate dehydrogenase complex (PDC) that catalyzes the rate-limiting step in aerobic glucose oxidation and thus plays a major role in the control of oxidative phosphorylation. To test this postulate, we employed a self-complementary adeno-associated virus (scAAV)-based delivery and expression system for targeting pda1 to the mitochondria of primary cultures of human hepatoblastoma (HB) and hepatocellular carcinoma (HCC) cells. Serotypes 1-10 scAAV vectors that included enhanced green fluorescent (egfp) reporter gene driven by either cytomegalovirus (CMV) or chicken beta-actin (CBA) promoters were analyzed for transduction ability of HB (Huh-6) and HCC (Huh-7 and HepG2) cell lines and primary cultures of normal human hepatocytes. Serotype 3 scAAV-egfp (scAAV3-egfp) vector was the most efficient and transduced up to 90% of cells. We limited the transgene expression primarily to liver cancer cells by generating scAAV3 vectors that contained the human alpha-fetoprotein promoter (AFP)-driven reporter gene (scAAV3.AFP-egfp) and the potentially therapeutic gene scAAV3.AFP-pda1. Infection of Huh-6 cells by the scAAV3.AFP-pda1 vector increased protein expression of E1α, PDC catalytic activity, and late-stage apoptotic cell death. Apoptosis was also associated with increased protein expression of Bcl-X/S, an early marker of apoptosis, and release of cytochrome c into the cytosol of infected HB cells. These data indicate that molecular targeting of mitochondrial oxidative metabolism in liver cancer cells by AAV3-mediated delivery of pda1 holds promise as a novel and effective therapeutic approach for human hepatic tumors