Prof. Stephen J. Beebe Profile

Prof. Stephen J. Beebe

Professor at Eastern Virginia Med School

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Publications (3)

Proceedings Article | 1 April 2005 Paper

Real-time imaging of membrane potentials during exposure to nanosecond pulsed electric fields

Juergen Kolb, Wolfgang Frey, Jody White, R. Price, Peter Blackmore, Stephen Beebe, Ravindra Joshi, Karl Schoenbach

Proceedings Volume 5692, (2005) https://doi.org/10.1117/12.591313

KEYWORDS: Luminescence, Pulsed laser operation, Molecules, Electrodes, Temporal resolution, Real time imaging, Microscopes, Cameras, Plasma, CCD cameras

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Proceedings Article | 1 April 2005 Paper

Dynamic effects and applications for nanosecond pulsed electric fields in cells and tissues

Stephen Beebe, Peter Blackmore, Emily Hall, Jody White, Lauren Willis, Laura Fauntleroy, Juergen Kolb, Karl Schoenbach

Proceedings Volume 5692, (2005) https://doi.org/10.1117/12.604449

KEYWORDS: Calcium, Phase modulation, Cell death, Picosecond phenomena, Tissues, Luminescence, Colon, Tumors, In vivo imaging, Green fluorescent protein

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Nanosecond, high intensity pulsed electric fields [nsPEFs] that are below the plasma membrane [PM] charging time constant have decreasing effects on the PM and increasing effects on intracellular structures and functions as the pulse duration decreases. When human cell suspensions were exposed to nsPEFs where the electric fields were sufficiently intense [10-300ns, ≤300 kV/cm.], apoptosis signaling pathways could be activated in several cell models. Multiple apoptosis markers were observed in Jurkat, HL-60, 3T3L1-preadipocytes, and isolated rat adipocytes including decreased cell size and number, caspase activation, DNA fragmentation, and/or cytochrome c release into the cytoplasm. Phosphatidylserine externalization was observed as a biological response to nsPEFs in 3T3-L1 preadipocytes and p53-wildtype and -null human colon carcinoma cells. B10.2 mouse fibrosarcoma tumors that were exposed to nsPEFs ex vivo and in vivo exhibited DNA fragmentation, elevated caspase activity, and reduced size and weight compared to contralateral sham-treated control tumors. When nsPEF conditions were below thresholds for apoptosis and classical PM electroporation, non-apoptotic responses were observed similar to those initiated through PM purinergic receptors in HL-60 cells and thrombin in human platelets. These included Ca²⁺ mobilization from intracellular stores [endoplasmic reticulum] and subsequently through store-operated Ca²⁺ channels in the PM. In addition, platelet activation measured as aggregation responses were observed in human platelets. Finally, when nsPEF conditions followed classical electroporation-mediated transfection, the expression intensity and number of GFP-expressing cells were enhanced above cells exposed to electroporation conditions alone. These studies demonstrate that application of nsPEFs to cells or tissues can modulate cell-signaling mechanisms with possible applications as a new basic science tool, cancer treatment, wound healing, and gene therapy.

Proceedings Article | 3 March 1995 Paper

Effect of submicrosecond electric fields on microorganisms: experiments and applications

Karl Schoenbach, Frank Peterkin, S. Beebe, D. Byars, R. Alden, P. Adolphson, T. Turner

Proceedings Volume 2374, (1995) https://doi.org/10.1117/12.205008

KEYWORDS: Bacteria, Microorganisms, Organisms, Capacitance, Cooling systems, Oceanography, Water, Information operations, Medical research, Energy efficiency

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