Biography:
Osama Ibrahim is a highly-experienced Principal Research Scientist with particular expertise in the fi eld of microbiology, molecular biology, food safety, and bioprocessing for both pharmaceutical and food ingredients. He is knowledgeable in microbial testing, microbial screening, culture improvement; molecular biology and fermentation research for antibiotics, enzymes, therapeutic proteins, organic acids and food fl avors; Biochemistry for metabolic pathways and enzymes kinetics, enzymes immobilization, bioconversion, and Analytical Biochemistry. Dr. Ibrahim was external research liaison for Kraft Foods with Universities for research projects related to molecular biology and microbial screening and holds three bioprocessing patents. In January 2005, he accepted an early retirement offer from
Kraft Foods and in the same year he formed his own biotechnology company providing technical and marketing consultation for new startup biotechnology and food companies. Dr. Ibrahim received his B.S. in Biochemistry with honor and two M.S. degrees in Microbial physiology/ fermentation and in Applied Microbiology. He received his Ph.D in Basic Medical Science (Microbiology, Immunology and Molecular biology) from New York Medical College. His research dissertation was on the construction of plasmid for the expression of a fusion protein of VEGF121/ Shiga-like toxin as a therapeutic protein for targeting angiogenesis (cancer treatment). Since 1979 he is a member of American Chemical Society, American Society of Microbiology, and Society of Industrial Microbiology.
Abstract:
Angiogenesis is a highly controlled process of growing new blood vessels under normal circumstances. However, in a large number of pathologies, such as solid tumor growth, angiogenesis is a crucial component of the disease process. Therefore, inhibitors of angiogenesis are being investigated as potential therapeutics for tumor growth. During angiogenesis endothelial cells of existing blood vessels undergo a complex process of reshaping, migration, growth, and organizing into new vessels. Vascular Endothelial Growth Factor (VEGF) is a central mediator of this process and acts via receptors whose
expression is restricted almost exclusively to endothelial cells. Because of its selectivity, VEGF represents a unique vehicle for delivery of inhibitors of angiogenesis to endothelial cells. Among potential inhibitors of angiogenesis, the shiga-like toxin-1 (SLT-I) produced by E. coli O157:H7 has the advantage that endothelial cells appear to be particularly sensitive to its action. The hypothesis that combining an SLT-I toxin with VEGF as a delivery vehicle would serve as a highly selective and active inhibitor of angiogenesis. To this end, fusion proteins containing VEGF121 and two forms of shiga-like toxin-I (SLT-I) were developed and tested in vitro for activities that have the potential to inhibit angiogenesis in vivo. Plasmids encoding the fusion proteins VEGF121/A1 containing the catalytically active fragment of the SLT-I A subunit and VEGF121/A containing the full length A subunit of SLT-I were constructed in pET-29a and pET-32a systems. Escherichia coli BL21 (DE3) pLysS bacteria were transformed with the plasmid constructs for the expression of these two fusion proteins. Both puri ed fusion proteins inhibited the translation of luciferase mRNA as a reporter gene in vitro translation system, indicating that both fusion proteins retain the N-glycosidase activity of SLT-I. However, only VEGF121/A1 fusion proteins displayed the ability to induce
auto-phosphorylation of the VEGF receptor KDR/FLK-1 and displayed a strong, selective growth inhibition of cultured cells expressing KDR/FLK-1 receptors. These results indicated that VEGF/SLT fusion proteins are promising therapeutic agents that can be developed into powerful and selective inhibitors of angiogenesis.