Biochemical alterations from normal mucosa to gastric cancer by ex vivo magnetic resonance spectroscopy.

BACKGROUND AND AIMS: The metabolic profile and morphologic aspects of normal and pathologic human gastric mucosa were studied. The aim of the present research was the application of ex vivo high-resolution magic angle spinning magnetic resonance spectroscopy (HR-MAS MRS) to the human gastric tissue to get information on the molecular steps involved in gastric carcinogenesis and the identification of biochemical markers useful for the development of in vivo MRS methodologies to diagnose gastric pathologies in clinical situations. METHODS: Twelve normal subjects, five with autoimmune atrophic gastritis, five with Helicobacter pylori infection, and five with adenocarcinoma were examined. Ten biopsies were taken during endoscopy from each patient. Specimens from carcinoma were also obtained during gastrectomy. Of the 10 biopsies, 4 were used for histologic evaluation, 4 were fixed in glutaraldehyde and processed for transmission and scanning electron microscopy, and 2 were immersed in liquid nitrogen and stored at -85 degrees C for monodimensional and bidimensional ex vivo HR-MAS MRS analysis. RESULTS: Ex vivo HR-MAS MRS identified glycine, alanine, free choline, and triglycerides as possible molecular markers related to the human gastric mucosa differentiation toward preneoplastic and neoplastic conditions. Ultrastructural studies of autoimmune atrophic gastritis and gastric adenocarcinoma revealed lipid accumulations intracellularly and extracellularly associated with a severe prenecrotic hypoxia and mitochondria degeneration. CONCLUSIONS: This is the first report of synergic applications of ex vivo HR-MAS MRS and electron microscopy in studying the human gastric mucosa differentiation. This research provides useful information about some molecular steps involved in gastric carcinogenesis. The biochemical data obtained on gastric pathologic tissue could represent the basis for clinical applications of in vivo MRS.

Ex vivo HR-MAS magnetic resonance spectroscopy of normal and malignant human renal tissues.

UNLABELLED: The aim of the present study was to examine the metabolic profile of normal and tumoral renal tissues by ex vivo high resolution magic angle spinning magnetic resonance spectroscopy (HR-MAS MRS). PATIENTS AND METHODS: Five patients, three affected by clear cell renal cell carcinoma (RCC) and two by papillary RCC, were examined. A radical nephrectomy was performed in each. In all patients, fresh tissue samples taken from normal cortex, normal medulla and tumor were collected and analyzed by mono-dimensional HR-MAS MRS. RESULTS: The spectra of human normal cortex and medulla showed the presence of differently distributed organic osmolytes as markers of a physiological renal condition. The marked decrease or disappearance of these metabolites and the high lipid content (triglycerides and cholesteryl esters) is typical of clear cell RCC, while papillary RCC are characterized by the absence of lipids and very high amounts of taurine. CONCLUSION: This paper demonstrates that ex vivo HR-MAS MRS is a viable and powerful means of probing for molecular information in human normal and tumoral renal tissues. This research will constitute the basis for a biochemical classification of renal neoplastic pathologies, especially for RCCs, which can be thus evaluated by in vivo MRS for clinical purposes. Moreover, these data may contribute to a better knowledge of the molecular processes for the basis of the onset of renal carcinogenesis.

Evaluation of the lipid composition of human healthy and neoplastic renal tissues.

The assumption that kidney tumors are characterized by high lipid content has directed our research towards the evaluation and comparison of lipids in healthy and neoplastic human renal tissues. This research appears to have marked importance owing to the role of lipids in cancer cell biochemistry. Nuclear Magnetic Resonance spectroscopy and chromatographic methods allow the full description of the lipidic profile typical of intact medulla, intact cortex, clear-cell renal carcinomas, chromophobe-cell renal carcinomas, oncocytomas and two samples of medulla infiltrated by a nephrocarcinoma. Significant differences among healthy, benign and malignant tissues were shown, and the results were discussed in relation to the different roles of each lipidic component and compared with the literature data.

Biochemical characterization of human brain and kidney tissues by magnetic resonance spectroscopy.

In vivo and in vitro Magnetic Resonance Spectroscopy is useful for monitoring changes in intracellular metabolites of human cerebral and renal tissues. Healthy and tumoral tissues of different histologic types have been characterized from a biochemical point of view. In vitro molecular characterization is performed on both the aqueous and lipid extracts of surgically removed tissue biopsies, after in vivo MRS, yielding a full picture of tissue biochemistry. Biochemical markers of healthy brain and kidney and of their relative neoplastic lesions have been disclosed. Moreover, some biochemical features can differentiate neoplasm within the same histological type. Ex vivo MRS also gives molecular information related to necrotic phenomena in glial tumors. MRS finding paralleled histologic data and new knowledge about the molecular base of proliferative neoplastic phenomena can be obtained.

Fast NMR evaluation of lipids in human tissues.

1H and 13C NMR spectroscopy was used to evaluate the degree of unsaturation and the cholesterol/cholesteryl ester ratio on the total lipid fractions obtained from human renal and cerebral tissues. The unsaturated/saturated fatty acid ratio was determined in the 13C NMR spectra from the ratio of the integrated areas of the resonances at 14.13 and 14.17 ppm assigned to the terminal methyl groups of saturated and unsaturated FA, respectively, and is validated by the traditional but time consuming gas-chromatographic analysis. Cholesteryl esters are easily discriminated in the total lipid fraction extracted from human tissues by means of the well-resolved component at 0.99 ppm (1H NMR spectra) of the resonance at about 1.00 ppm generally assigned to free cholesterol. The role of NMR spectroscopy in the study of lipidic biochemistry of human tissues is confirmed.