ABSTRACT
Swelling of the intervertebral disc nucleus pulposus may be a contributing factor in lower back pain syndromes. We have designed and tested a new osmometer for in vitro determination of nucleus pulposus swelling pressure. The functional principle of the osmometer involves compressing a sample of nucleus pulposus with nitrogen gas until saline pressure gradients across a 0.45-micron Millipore filter are eliminated. Swelling pressures of both pooled dog and pooled pig lumbar disc nucleus pulposus were measured on the new osmometer and were compared with swelling pressure determined using the equilibrium dialysis technique. The osmometer measured swelling pressures comparable to those obtained by the dialysis technique. This osmometer provides a rapid, direct, and accurate measurement of swelling pressure of the nucleus pulposus.
Subject(s)
Intervertebral Disc/physiopathology , Animals , Back Pain/etiology , Back Pain/pathology , Back Pain/physiopathology , Dogs , Intervertebral Disc/pathology , Intervertebral Disc Displacement/pathology , Intervertebral Disc Displacement/physiopathology , Methods , Osmotic Pressure , Swine , Swine, MiniatureABSTRACT
Expert diagnosticians draw upon rich, integrated structures of knowledge and associated action rules to achieve their prodigious performances. Studies in both medical diagnosis and electronic troubleshooting have revealed that it is particularized knowledge that plays a vital role for experts in both domains, not inexplicable powers of intuition. Advanced knowledge engineering methods have been developed and applied in a number of Air Force technical domains so that experts' mental databases and procedural libraries can be made explicit enough to serve as targets of instruction. Instructional principles have been derived from this knowledge engineering work and are guiding the development of a new generation of Air Force technical training systems. The training dictum is to teach from realistic cases so that theory of system operation and specialized solution methods are taught in tandem. The learning environments will further foster the welding of factual knowledge to action rules by providing "assisted laboratory" experiences via intelligent tutoring systems. In these environments, trainees can practice carrying out diagnoses on increasingly complex problems with the help of an articulate expert coach.
