blank spacer gif Proposed Statement of Research
Aretha J. Hollis
Texas A&M University

Laser microbeams offer potential advantages as accurate manipulating tools for cellular and subcellular organelles. The high precision of laser beams, along with the possibility of narrowing beam spot size from 500-800 microns (used for tissue microsurgery) to 0.5-3 microns (needed for cellular microsurgery), suggest adaptability for in vitro fertilization. Thus, a key motivation for using lasers is the ability to precisely affect small targets. Work done on controlled ablation of holes through mouse zone pellucida, the outer membrane of the egg cell, has established the capability of a 1.48 1lm diode laser for the procedure. This is a novel, inexpensive, robust, continuous wave, diode laser system capable of microsurgical procedures at the cellular level with high resolution and high reliability in conjunction with a laboratory microscope. Its wavelength (1.48 µm) is near a peak absorption band for water at which absorption appears to be high enough to confine thermal effects on cellular biomaterials, yet low enough to allow the transmission and focusing of the laser through a water-based solution. The technique has also been tested successfully to term in humans as well. Optimization of the procedure can be achieved if the mechanism by which this technique works is properly understood. Furthermore, the understanding of how laser locally dissolves cellular material has tremendous potential for other applications in cellular and subcellular laser microsurgery

This technology has potential use in space applications as well. First, the National Aeronautics and Space Administrations' (NASA's) Life Sciences Program uses space as a research laboratory to address key issues in basic biology and physiology and to apply the results of this research to biomedical problems on Earth. For example, it aims to understand the effects of radiation on a cellular level to prevent mutations and carcinogenesis. The Life Sciences Program also seeks comprehension of physiology in space to advance scientific and medical research with the intent of improving the quality of life on Earth. Regulatory physical investigations have contributed to the understanding of disorders such as hypertension and anemia. It is possible that similar investigations, as the proposed research, will facilitate understanding of infertility. Furthermore, the understanding of the effects of space on biological systems is also necessary for the design of self-contained life support systems, especially in long-duration space travel. Plants are a critical component of such a life support system. Research on plant cell cultures in space has shown that removing gravity affects factors such as shape, form, productivity, and genetic composition. This lightweight and compact diode laser system could have excellent applications in plant cell studies because of its high resolution and reliability.

Specifically, this project will involve both theoretical and experimental aspects. I will model and analyze the processes of laser-tissue interaction for this procedure. Analytical solutions will involve Green's function solutions, while numerical solutions will involve two-dimensional axisymmetric fmite difference and finite-element methods. Pore size, laser power and pulse duration, number of pores, and the geometry of irradiation (tangential and radial) are the main variables that will be tested in the proposed studies. The main hypothesis to be tested is whether the process of drilling can be fully described by a localized thermolysis process based on a rate dependent dissolution of glycoproteins. The long-term goal of this project is to develop procedures that can be used for treatment of infertility in humans. Ideally, our results will be applied to other medical problems and related biological research involving microsurgical manipulations at the cellular level.


Wednesday, 26-Mar-2003 22:08:01 CST