RESUMO
The low-resolution proton nuclear magnetic resonance (NMR) spectra of human pancreatic adenocarcinomas maintained in nude mice and in culture exhibit characteristic features. First, the high values of longitudinal (T1) and transverse (T2) relaxation times were attributed to disturbances in the exchange of ions and water molecules in cancerous cells. Second, a new peak situated at about 1.8 +/- 0.2 ppm from the peak of tissular water was observed. It was higher in spectra recorded from the proliferative peripheral zone of the tumor than from the central necrotic zone and was not observed in healthy control pancreatic tissue. Histological examination of the xenografts by transmission electron microscopy indicated intense phospholipid metabolism with marked development of the plasma membrane and the presence of numerous secretory granules, lysosomes, and multivesicular bodies in the cytoplasm. The new 1H NMR low-resolution peak was thought to reflect an increase in membrane viscosity stemming from alterations in the structure and metabolism of membrane phospholipids. Whatever its origin, the 1.8-ppm peak is a particular feature of cancerous pancreatic cells, which should be readily detectable by NMR in vivo.
