Sarcosine ethyl ester

A gas chromatographic method for the determination of N,N-dimethylglycine in urine has been developed. After clean-up by cation-exchange, N,N-dimethylglycine was derivatized with ethanol and hydrochloric acid to form the corresponding ethyl ester. After evaporation of solvent, N,N-dimethylglycine ethyl ester was extracted into methylene chloride and chromatographed on a gas chromatograph equipped with a packed column containing 10% Carbowax 20 M. The detection limit of the method is 0.01 mM N,N-dimethylglycine in urine. This method has been used to detect N,N-dimethylglycine in urine from healthy subjects as well as in urine from patients with metabolic disorders. These findings were verified by gas chromatography-mass spectrometry.

The aim of the present study was to investigate the expression and function of forkhead box protein 3 (FOXP3) in gastric cancer using a rat model. A total of 92 Wistar rats were divided into two groups: An experimental group (n=46) and a control group (n=46). In the experimental group, sarcosine ethyl ester hydrochloride and sodium nitrite carcinogens were administered for 6 months to induce gastric cancer, whereas the control group was administered saline. Reverse transcription-polymerase chain reaction, immunoblotting, immunohistochemistry and western blotting were applied to analyze FOXP3 expression in gastric cancer and normal gastric tissue in the experimental and control groups, respectively. The association between FOXP3 expression and gastric cancer pathogenesis was investigated. In the experimental group, 6/46 rats developed hyperplastic lesions (grade I), 8 rats developed precancerous lesions (grade II), 18 rats developed early stage gastric cancer (grade III) and 14 rats developed gastrointestinal invasive carcinoma (grade IV). FOXP3 transcription and expression was observed in all gastric tissues of the experimental group. FOXP3 transcription and expression levels were significantly higher in the experimental group than in the control group (P<0.05). Furthermore, in the experimental group, a higher lesion grade was associated with a higher level of FOXP3 transcription and expression (P<0.05). FOXP3 protein was predominantly distributed in the tumor nuclei of the gastric cancer tissues. In the 32 pathological slices of gastric cancer tissue obtained from the experimental group, 20 cases (62.50%) exhibited positive FOXP3 staining. In the hyperplastic (grade I) and precancerous gastric (grade II) tissues, 2 cases (33.33%) and 4 cases (50.00%) exhibited positive FOXP3 staining, respectively. However, no positive FOXP3 expression was identified in the 46 pathological gastric tissue slices obtained from the control group. In conclusion, the expression of FOXP3 exhibits a positive correlation with gastric lesion grade. Therefore, FOXP3 may exhibit an important function in the occurrence and development of gastric cancer.

Cancers and precancerous lesions of the esophagus were efficiently induced in rats by the simulation of a clinico-epidemiological setting; that is, the administration of precursors of nitrosamine. Six week old non-inbred male Wistar rats were given 2g/kg bodyweight of sarcosine ethyl ester hydrochloride (SEEH) and concurrently 0.3g/kg bodyweight of sodium nitrite (NaNO2), precursors of N-nitrososarcosine ethyl ester (NSEE), in 2% sucrose as drinking water. Group 1 received the precursors twice a week for 6 weeks followed by 8 weeks observation, and group 2, once every 3 days for 7 weeks followed by 26 weeks observation. At the end of treatment, no tumor had developed in the esophagus of rats in group 1, but the [3H]-thymidine labeling indices in both basal and superficial layer cells were higher than in the control group. On subsequent observation, papillomas appeared in group 1 (33.3%), and carcinomas in group 2 (33.3%), within 4 weeks. The tumors induced in group 1 were mostly papillomas and rarely carcinomas. When the observation was prolonged in group 2, 100% of the animals had cancer in week 20. The pathological changes of the lesions paralleled the sequential development of human squamous cell carcinoma of the esophagus. Our system has the advantages in that papillomas and cancers can be induced in rats in a short time and the agents used are less toxic than preformed nitrosamines administered previously by gastric intubation. It would serve as a useful experimental tool to study premalignant lesions and cancers of the esophagus.