LOCATION : Wiley Building TIME: 6:30 pm
1500 Paint Branch Parkway
College Park, MD 20740
Room 1A001
currently a JIFSAN student at FDA
Title: pH and Temperature Stability of Shiga-like Toxins 1 & 2
Shiga toxins and Shiga-like toxins (Stx) are a relatively large group of cytotoxins produced by certain serotype of Shigella and E. coli (STEC), which are responsible for hemolytic uremic syndrome. These toxins consist of 5 small subunits responsible for binding to an outer membrane ligand on host cells, and surround the larger, biologically active subunit. Once transported into the cell, the subunit interacts with and inhibits ribosomal protein synthese. This results in the induction of apoptosis in a variety of cell types...The flow cytometry method used, based on binding R-pycoerytherin-labeled annexin V to exposed membrane phosphatidyl serine, is sensitive and highly quantitative, in addition to being widely accepted as a marker for early apoptotic events. There was a greater loss of biological activity at acid pH than at nuetral pH. The combination of acid pH and higher storage temperature resulted in the greatest degree of toxin inactivation. We estimate the this loss of activity is betweeen 10 and 100 fold at low pH. Positive controls for inactivation, including inhibition by monoclonal antibodies, and heat treatment resulted in complete or near complete inactivation of the toxins.
Animal Science, Animal and Avian Science Dept.
Title: Equine Obesity and Associated Metabolic Disorders
Equine obesity is a growing problem in companion horse populations leading to excessive
accumulate of adipose tissue on the horse's body. Adipose tissue is a potent producer of pro-inflammatory cytokines, hormones involvved in energy balance, and acute phase proteins.
Increases in these substances have been either directly or indirectly associated with a group
of equine metabolic disorders including insulin resistance and laminitis. When combined
with obesity, the condition is know as Equine Metabolic Syndrome.
Title: Determination of species range and virulence in
Plasmodium falciparum malaria
Plasmodium malaria parasites infect the blood of a wide range of vertebrates with a high degree of host specificity. Host sharing and cross-species transmission occurs rarely. Therefore, while animal models are required for drug development and vaccine studies, only higher primates and New World monkeys can be experimentally infected with the human malarias. Only a few P. falciparum lines can infect New World monkeys, and the virulence and disease of these lines often differ substantially from human P. falciparum malaria infections. To explore the nature of this species restriction and to identify determinants critical to the use of the P. falciparum-Aotus model in malaria research, we have completed a genetic cross between a P. falciparum clone unable to infect Aotus and a clone highly virulent to these monkeys. Thirty-three independent recombinant progeny have been isolated and typed with microsatellite markers at 3 cM resolution. Linkage analysis of this cross maps Aotus infectivity to a 13kb locus on chromosome IV containing 2 genes. Genetic manipulations are offering insights into the gene underlying the virulence/invasion phenotype and will be discussed.
Title: Antibiotic, Prebiotic and Probiotic Treatment for Salmonella sp. Reduction in Commercial Laying Hens
Salmonella enterica subsp. enterica serotype enteritidis can be responsible for food borne illness from the ingestion of contaminated poultry meat and eggs. Table eggs can become infected with Salmonella sp. when hens have a systemic infection that invades ovarian tissues. The efficacy of antibiotics, prebiotics and probiotics or products in combination was evaluated by the level of Salmonella reduction in commercial chicks...In four trials, the products demonstrated a rate of Salmonella enteriditis phage type 8 (SEPT8) reduction in tissues from 21.1% to 98.0% compared to positive controls. Mortality was not significantly impacted by the treatment products in three of the four frials and feed intake by any of the dietary or drinking water additives. Future studies will evaluate commercial products in laying hens during stressful periods of maximun egg production, with the goal of ultimately reducing the number of Salmonella positive eggs that could be ingested by consumers.
