Metabolite composition in breast tumors examined by proton nuclear magnetic resonance spectroscopy.

BACKGROUND: In vivo characterisation of breast tumors using protein (1H) MR spectroscopy relies upon in vitro interpretation of tissue samples. The present study has investigated metabolite composition in extracts from breast tumors and non-involved breast tissue. Multivariate data analysis was used to determinate combinations of metabolites important for differentiation. MATERIALS AND METHODS: Tumor and non-involved breast tissue were obtained from 16 patients undergoing surgical treatment. 1H NMR spectra of perchloric acid tissue extracts were obtained at a BRUKER Avance DRX600 spectrometer. The data was analysed using principal component analysis and probabilistic neural networks. RESULTS: Low levels of glucose and high content of choline compounds were dominant findings in the tumor spectra. Principal component loadings demonstrated this strong association. The spectra were correctly classified using neural network analysis. CONCLUSIONS: Large differences in the metabolite composition of breast tumors and surrounding breast tissues have been documented.

Dexamethasone and dexamethasone phosphate detected by 1H and 19F NMR spectroscopy in the aqueous humour.

To apply nuclear magnetic resonance (NMR) spectroscopy to study the penetration of dexamethasone phosphate into the aqueous humour from rabbit following topical administration. After topical administration of 0.1%, 1.0% and 10% dexamethasone phosphate solutions, respectively, samples of aqueous humour were aspirated, freeze-dried, redissolved in deuterium oxide and analyzed by high resolution 1H and 19F NMR spectroscopy. In order to study the lipophilic and hydrophilic metabolites of the drug, samples obtained after application of 1% dexamethasone phosphate were extracted with methanol/chloroform, and then extracted with perchloric acid. In all samples obtained from eyes denuded of the corneal epithelium prior to administration of dexamethasone, signals corresponding to the chemical shifts of the drug were identified in 19F NMR spectra. In the experiments performed with 1% dexamethasone phosphate, both dexamethasone and dexamethasone phosphate were detected in the aqueous humour. Using 10% dexamethasone phosphate solutions, signals from the drug were detected in 1H NMR spectra simultaneously with signals from about twenty other substances present in the aqueous humour. NMR spectroscopy appears to be a valuable method for studying dexamethasone metabolism and penetration into ocular tissues. It provides simultaneous detection of both the drug metabolites and other substances in the sample and might offer a complementary approach to other analytical methods.