Studies on the absence of photodynamic mechanism in the normal pancreas

Thomas S. Mang; Thomas Jeffery Wieman M.D.; David H. Crean

doi:10.1117/12.44058

1 June 1991 Studies on the absence of photodynamic mechanism in the normal pancreas

Thomas S. Mang, Thomas Jeffery Wieman M.D., David H. Crean

Proceedings Volume 1426, Optical Methods for Tumor Treatment and Early Diagnosis: Mechanisms and Techniques; (1991) https://doi.org/10.1117/12.44058
Event: Optics, Electro-Optics, and Laser Applications in Science and Engineering, 1991, Los Angeles, CA, United States

Abstract

Extraction procedures to quantitate porfimer sodium concentration in tissues were correlated with fluorescence measurements made in vivo, on hamster and rat normal pancreas and intra-pancreatic tumors. The uptake of photosensitizer has been shown to be high in both normal and malignant pancreatic tissues, in both animal models studied. Photobleaching of the drug, as evidenced by both techniques within the pancreatic tumor, occurs in a typical manner during PDT, with resultant tissue destruction. In contrast, when the normal pancreas is exposed to PDT, a negligible photobleaching effect, as well as a lack of tissue response, is observed. The lack of observable response is corroborated by a lack of measurable physiological response. Both serum amylase and serum glucose show acute changes up to 12 hours post treatment but quickly return to normal. HPLC analysis shows that the drug extracted from both the normal pancreas and intrapancreatic tumor is essentially the same as that extracted from other tissues and similar to that which has been injected into the animal. Fluorescence microscopy has shown that at time points between 12-120 hours the drug is associated with lymphatic channels. This would not, however, necessarily preclude normal tissue destruction. Similar results have been found with other photosensitizers. Understanding the lack of response in the pancreas may lead to a deeper understanding of the diseased state which is normally refractory to all therapy as well as understanding the fundamental concepts of the mechanisms of PDT.

Citation Download Citation

Thomas S. Mang, Thomas Jeffery Wieman M.D., and David H. Crean "Studies on the absence of photodynamic mechanism in the normal pancreas", Proc. SPIE 1426, Optical Methods for Tumor Treatment and Early Diagnosis: Mechanisms and Techniques, (1 June 1991); https://doi.org/10.1117/12.44058

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