Biomedical subjects
Publications and source records attributed to R Cothren.
We are investigating the use of optical spectroscopy (fluorescence, reflectance, Raman scattering) for detecting precancerous lesions in the mucosal linings of hollow organs. We present a morphological model for extracting quantitative pathological information from fluorescence spectra, using colonic dysplasia as an example. The potential of this technique in providing histological information in real time without the need for tissue removal is discussed.
This study evaluates the welding effect of argon laser on fascial grafts and its potential application in tympanoplasty. An animal model was designed so that surgically induced perforations of the lumbar fascia of the animals were grafted in an underlay fashion. Each graft was "spot welded" around the circumference of the perforation using a hand-held argon laser. Various lasing parameters were used on different grafts. Control perforations were grafted but not welded. A total of 96 perforations was studied. Weld sites were evaluated both histologically and by tensile strength measurement at the end of surgery, and at 7, 14, and 21 days postoperatively. Comparison with controls showed a higher tensile strength for welded grafts, which was most significant in the early postoperative period (p < 0.001). Histologically, it seems that the basic mechanism of fascial welding involves liquification and denaturation of extravasated proteins at the weld sites. Correlation between the extent of thermal damage on the tissues and the various lasing parameters is described. Based on the well-documented safety of argon laser in otologic surgery, and the successful welding of fascial grafts in this study, argon laser may prove beneficial in welding temporalis fascia grafts in tympanoplasty.
This communication demonstrates that fluorescence spectra of human aorta with good S/N ratios can be collected using an optical fiber laser catheter. The performance of this catheter is compared to a non-fiber optic collection system with an equivalent delivery/collection geometry. For a given sample, fluorescence lineshapes obtained using the two systems are identical; differences in peak fluorescence intensity are related to the different collection efficiencies of the two systems. It is shown that the fluorescence lineshape of arterial tissue depends on the delivery/collection geometry of the detection system, and that this is due to the interaction of absorption and fluorescence within the artery wall. This effect is investigated systematically using a specially designed collection system. Results are analyzed qualitatively using a simple, one-dimensional model of tissue fluorescence. With this analysis, we present design requirements for a collection system in which such geometric effects are eliminated, and show that our optical fiber laser catheter satisfies these requirements.