Biomedical Engineering - Audio W. Mark Saltzman

In this final lecture, Professor Saltzman talks about artificial organs, with a stress on synthetic biomaterials. First, the body's responses (immunological and scar healing responses) to foreign materials are introduced. This leads to discussion of different types of polymer/plastic materials (i.e., Dacron and GORE-TEX) and their properties. Next, Professor Saltzman talks about the design and function of some artificial organs, such as lens implants, heart valves and vessels, hip, dialyzer, heart/lung bypass machine, and the artificial heart. Lastly, challenges and areas for improvement in the field are presented.

Professor Saltzman uses cancer diagnosis and treatment as an example to demonstrate the some applications of biomedical engineering technologies and methods. Some issues involved in cancer treatment, such as tumor angiogenesis, radiation sensitivity, drug localization, and cancer stem cells are mentioned. Next, he describes the phases (I-IV), in compliance to guidelines enforced by the Food and Drug Administration (FDA), which a new drug compound must go through to gain approval prior to public distribution/sale. Finally, Professor Saltzman draws attention to the areas that biomedical engineers may contribute to, to improve this process.

In this lecture, Professor Saltzman continues his discussion of tissue engineering, and its role in facilitating healing, tissue regeneration, organ replacement, drug delivery and as model for studying human physiology. Specific examples from current research by scientists at Yale are used to illustrate some of these points and to highlight the current progress in the field. Some examples are generating neo-tissues from hydrogel scaffold seeded with cells, healing spinal cords and controlling mechanical properties of newly grown blood vessels with external conditions.

Professor Saltzman continues his discussion of biomedical imaging technology. Magnetic resonance imaging (MRI) is introduced as an alternate form of imaging, which does not use ionizing radiation yet can provide detailed structure of the body. Functional MRI (fMRI) has a different application from traditional MRI. It can be used to measure oxygen consumption (tissue metabolic rate), and is an important tool in deciphering brain function. Third, ultrasound imaging is another imaging technique that can detect motion by translating sound wave reflections into structural images at fast timescale. Finally, examples of nuclear imaging and advances in light microscopy are discussed.

Professor Saltzman motivates the need for tissue engineering, and describes the basic elements of the tissue engineering approach. Professor Saltzman defines three different types of tissue transplants: autografts, allografts, and xenografts. An online resource for organ donors/recipients is presented, which stresses the great need for donors, and the important contribution of tissue engineering in producing/growing organs that can be used for this purpose. Next, Professor Saltzman compared drug and gene therapy, and discusses the use of stem cell in tissue engineering for wound healing. The need for compatible biomaterials to support growth and differentiation of stem cells into functional organ is also highlighted.

Professor Saltzman begins the lecture with discussion of the importance of motion for the survival and propagation of any living species. He presents the different modes of motion, taking first the example flight to talk about force balance, such as the magnitude of propulsive force that must be generated overcome drag to produce forward motion. Next, the mechanics of walking, running, cycling and swimming is discussed, with emphasis on efficient use of energy, overcoming drag and friction, and the influence of organism shape and size. An equation to calculate drag force of a spherical object of radius, r, moving at velocity, v, in a medium with viscosity, μ, is introduced: Fd = 6πvμr. Finally, Professor Saltzman talks about design of the artificial hip, which biomedical engineers must take into consideration the biomechanics and natural function of the pelvic bone.