Theses, Dissertations and Student Research Papers (Pharmacy)

Investigation of unique marine environments for microbial natural products

2013-04-01T23:26:23Z

Investigation of unique marine environments for microbial natural products Thornburg, Christopher C. Metagenomics has revealed that the marine microbial biosphere is immensely more diverse than originally considered, and is an almost untapped reservoir for the potential discovery of microbial natural products. Despite numerous advances in culturing, biosynthetic engineering and genomic-based screening efforts to uncover much of this diversity in relatively accessible environments, a high rediscovery rate has resulted in the investigation of unique, relatively unexplored ecosystems harboring phylogenetically diverse communities of marine organisms. The focus of this research was to establish a culture repository of microorganisms collected from the Red Sea and from deep-sea hydrothermal vents, and to assess their biosynthetic potential for the production of new chemical scaffolds. Cultivation of marine cyanobacteria from the Red Sea has led to the identification of five new cyclic depsipeptides, apratoxin H, grassypeptolides D and E, Ibu-epidemethoxylyngbyastin 3 and leptochelin, the latter possessing a unique chemical scaffold capable of binding metals. A collection of deep-sea hydrothermal vent sediment and microbial mat samples led to the isolation of 64 unique bacterial strains, with eight assigned as members of the order Actinomycetales. Importantly, these isolates, along with a collection of deep-vent invertebrates and microbes, have led to the development of methods for the collection, culturing and biological screening of organisms from this extreme environment for future natural products research. Graduation date: 2013

Formulation of an oral acetylsalicylic acid suspension and pharmacokinetics of parenteral thrombomodulin analogues

2013-03-15T19:36:50Z

Formulation of an oral acetylsalicylic acid suspension and pharmacokinetics of parenteral thrombomodulin analogues Piepmeier, Edward H. Sustained concentrations of active compound were maintained in vitro and in vivo for an oral and a parenteral dosage form respectively. The vehicle of a oral dosage form was modified and the molecular structure of a parenteral dosage form was modified. An oral dosage form was tested in vitro using dissolution apparatus. A parenteral dosage form was tested in vivo using rats. A new oral suspension dosage form for acetylsalicylic acid was compared to two controlled release forms and two immediate release dosage forms which are currently commercially available. A parenteral thrombomodulin analogue conjugated to polyethylene glycol was compared to the unconjugated thrombomodulin analogue. In each case the goal was to maintain sustained concentrations of active compound. Graduation date: 1991

Calcium alginate gels in oral dosage form design

2013-03-14T16:47:49Z

Calcium alginate gels in oral dosage form design Lin, Shun Yih In vivo research following ingesting of commercially available Lactobacillus tablets, which contain about 2X10⁶ cfu/tablet of Lactobacillus acidophilus and Lactobacillus bulgaricus cells in a dose of four tablets daily, showed serum lipoprotein concentrations did not change significantly. In order to increase the number of viable Lactobacillus bacteria after challenging in low pH solution (gastric fluid), enteric coating polymer was applied over dried calcium alginate beads containing Lactobacillus. Survival of Lactobacillus bacteria was generally higher from freeze dried calcium alginate beads compared to vacuum dried products. However, after pretreatment with simulated gastric fluid (pH = 1.5) for 2 hours, only the coated products from vacuum drying showed promising results. Lactobacillus bacteria were fully protected against gastric pH after formulating the bacteria inside mini-tablets which were coated with Eudragit L30D, an enteric coating polymer. Alginic acids are naturally occurring substances found only in the brown seaweeds. Alginic acid salts formed with most di-, and polyvalent metals are insoluble in water. The most common application of alginate precipitation in drug product formulation is based on insolubilization of alginate by addition of calcium salt. By altering the composition of calcium alginate, drug loading, enteric coating thickness, and sustained release coating thickness, the lag time for drug dissolution can be controlled. This formulation research provides oral dosage form design for targeted delivery of drug to any desired site in the gastrointestinal tract. Examples of site specific targeted delivery are given for Lactobacillus bacteria, ibuprofen, sulfasalazine, and 5-aminosalicylic acid. Graduation date: 1991

Development of novel oral enteric-coated aquaculture vibrio vaccines

2013-03-14T16:33:10Z

Development of novel oral enteric-coated aquaculture vibrio vaccines Wong, George Kaon An oral Vibrio vaccine for salmonids was developed. The vaccine was produced by spray coating lyophilized formalin-killed whole cells of Vibrio anguillarum (VA LS 1- 74) onto non-pareil sugar beads. Then methacrylic acrylic acid copolymer (Eudragit L-30D) was applied as an enteric protective coating. Using x-ray radiographic techniques, it was found that large particles (> 1.1 mm) remain in the fish stomach for more than 2 hours before they would enter the pyloric caeca. The pyloric sphincter which has an opening of 0.94 mm, acts as barrier to prevent the passage of large food particles in the stomach to the pyloric caeca. Based on this information non-pareil sugar beads of 18-20 mesh or smaller should be used as the vaccine carriers. A 15% (w/w) Eudragit L-30D coating is needed to provide enteric protection of the vaccine loaded sugar beads of 18-20 mesh size. Lower levels of coating resulted in the bead breaking down in the stomach and releasing contents prior to entering the pyloric caeca. Since the lymphoid tissues are diffuse throughout the whole GI tract, it may not be necessary to target a vaccine to deliver antigens to a specific area of the intestinal tract, but only protect the antigens from gastric fluids. In vitro dissolution studies indicate that 10% VA LS 1- 74 loading was sufficient for rapid vaccine release (42% released in 30 minutes) and a 15% Eudragit L-30D coating was suitable for providing protection against stomach acid. The vaccine product used in vivo studies contained 10% VA LS 1- 74 and 15% Eudragit L-30D on non-pareil sugar seeds of 18-20 mesh size. Coho salmon were given the vaccine orally, and 30 days afterward a live challenge test was performed. There was no significant difference in the survival rates in a live bacteria challenge test with the positive control (83.3%) and test (80.3%) groups. Both had higher survival rates than the no vaccine fed control group. The serum and mucosal antibody levels to Vibrio were significantly higher (p<0.01) in the test group (19700 units/ml) than the other two groups (2530 units/ml in the positive control group and 617 units/ml in the negative control group). The antibody titer appears to be a better indicator for vaccine efficacy than survival rate of live bacteria challenge tests. The oral Vibrio vaccine developed is effective, and the technique to protect the antigen can be applied to other antigens or proteins for oral delivery producing an economical pathway for mass vaccination of fish. Graduation date: 1991