Characteristics of Small Intestinal Diseases on Single-Balloon Enteroscopy: A Single-Center Study Conducted Over 6 Years in China.

The small intestine has been considered inaccessible for a long term. The development of single-balloon endoscopy has greatly improved the diagnosis and treatment possibilities for small intestinal diseases.In this study, we aimed to explore the demographic characteristics and small intestinal diseases of patients who underwent single-balloon enteroscopy between 2009 and 2014 at our endoscopy center. We determined the enteroscopic findings for each small intestinal disease and the most susceptible age groups.In total, 186 patients were included in the study. Their mean age was 45.87 ± 15.77 years. Patients who underwent single-balloon enteroscopy were found to have neoplasms (most common age group: 14-45 years, most common lesion location: jejunum), lymphoma (46-59 and 60-74 years, ileum), protuberant lesions (45-59 years, jejunum), inflammation (14-45 and 46-59 years, ileum), benign ulcers (14-45 years, jejunum), diverticulum (14-45 years, ileum), vascular malformations (60-74 years, jejunum), polyps (14-45 years, jejunum), Crohn's disease (14-45 years, jejunum), hookworm infection (14-45 years, jejunum), lipid pigmentation (14-45 and 46-59 years, jejunum), undetermined bleeding (46-59 years, ileum), or undetermined stenosis (31 years, duodenum). Each small intestinal disease had distinct enteroscopic findings.

Quantitation of the synergistic interaction of edatrexate and cisplatin in vitro.

Cytotoxicity studies combining edatrexate (EDX) and cisplatin (Cis-Pt) were carried out in HL-60 cells in vitro as a retrospective analysis of the same combination in animal models and as a prospective study of this combination for future clinical trials. For purposes of comparison, parallel studies were carried out using methotrexate (MTX) and Cis-Pt. Dose-effect relationships were analyzed by the median-effect principle and the combination index-isobologram technique. EDX was the most cytotoxic agent of the three examined. The doses effective in 50% inhibition of the cell proliferation (ED50 values) for EDX, MTX, and Cis-Pt were 0.001, 0.0043, and 1.08 microM, respectively. Synergism occurred at effect levels corresponding to greater than 65% inhibition of cell growth by EDX + Cis-Pt, with an increase in synergism being observed at high doses. By contrast, MTX + Cis-Pt exhibited moderate synergism, with a decrease in synergism being noted at high doses. Preceding one drug by another for 4 h during the 48-h incubation period did not result in synergism greater than that produced by simultaneous exposure to both drugs for both pairs of combinations. Due to the synergism arising from these combinations, the ED90 values can be reduced by as many as 52 and 7.3 times for Cis-Pt and EDX, respectively, as compared with only 4.0 and 1.9 times for Cis-Pt and MTX, respectively. The calculation of these drug interactions was carried out automatically with the use of computer software and was also illustrated by a sample calculation performed without computer simulation.

Selective distribution of selenium in colon parallels its antitumor activity.

Results of epidemiologic and experimental studies suggest that selenium can inhibit the development of tumors. In rats, the administration of selenium decreases the incidence of carcinogen-induced colon tumors; the inhibition is greater in the proximal colon that in the distal colon. We investigated the distribution of selenium in the different segments of rat colon and determined the uptake of selenium in the mucosa and in the muscle layers of each segment. The colon was perfused before removal of the segments to ensure complete removal of blood-borne selenium. We found that the concentration of selenium was greater in the proximal colon than in the distal colon and that within each segment the uptake was higher in mucosa than in muscle. In addition, we determined the level of selenium in blood, serum, and liver at different times after the administration of various doses of selenium. Though the mechanism by which selenium prevents tumor development is unknown, the data indicate a correlation between the uptake of selenium in different segments of colon and inhibition of tumorigenesis.

Selenium and the acute effects of the carcinogens, 2-acetylaminofluorene and methylazoxymethanol acetate.

Selenium inhibits the development of 2-acetylaminofluorene-induced hepatic tumors and methylazoxymethanol-induced colon tumors. It has been suggested that selenium exerts these protective effects by inhibiting metabolic activation of the carcinogen. We have studied the effects of selenium upon the acute inhibition of RNA and DNA synthesis induced by 2-acetylaminofluorene or methylazoxymethanol in intact liver, regenerating liver, and colon of weanling male Sprague-Dawley rats. Some animals received selenium in the drinking water (4 ppm) for 1 week, while others received a single injection of selenium (1 mg/kg i.p.) prior to being treated with the carcinogens. No protection against the effects of the carcinogens on RNA or DNA synthesis was noted with either treatment of selenium. Disulfiram did protect against the 2-acetylaminofluorene-induced inhibition of hepatic RNA synthesis, and pyrazole prevented the inhibition of RNA synthesis induced by methylazoxymethanol in both liver and colon. Serum selenium levels are reported. The data indicate that selenium does not influence the acute alterations induced by the carcinogens 2-acetylaminofluorene or methylazoxymethanol and suggest that the tumor-preventive effects of selenium are probably due to a mechanism other than interference with carcinogen activation and interaction with cellular macromolecules.

Inhibition of methylazoxymethanol-induced intestinal tumors in the rat by pyrazole with paradoxical effects on skin and kidney.

Methylazoxymethanol is a potent carcinogen and induces tumors predominantly of the small intestine and colon following a single injection. Previous data indicated that alcohol dehydrogenase could convert this carcinogen to a reactive alkylating agent. Rats were treated with an inhibitor of this enzyme, pyrazole, 2 hr prior to their receiving the carcinogen. The development of intestinal and colonic tumors was prevented. The rats did, however, develop numerous tumors of the skin and kidney. Analyses of the complete autopsies are presented. The data indicate that intestinal and colonic alcohol dehydrogenase plays a role in the tumorigenic effects of methylazoxymethanol and that other non-pyrazole-sensitive enzymes exist in other organs that can also activate this carcinogen.

Histochemical findings suggesting that methylazoxymethanol, a liver and kidney carcinogen, is a substrate for hepatic and renal choline dehydrogenase.

Methylazoxymethanol (MAM) is a potent carcinogen and induces tumors predominantly in rat liver, colon and kidney. The findings reported in this paper suggest that MAM is a substrate for the enzyme choline dehydrogenase located in rat hepatocytes and in the terminal portion of the renal proximal convoluted tubule. As with the natural substrate choline, this reaction with MAM did not require NAD+, was not inhibited by pyrazole and was dependent on the electron transfer reagent, phenazine methosulfate. The product of this reaction is probably the same as that obtained from the metabolism of MAM by alcohol dehydrogenase, namely, an unstable aldehydic derivative which decomposes rapidly to carbonium ions. The reaction with alcohol dehydrogenase offered an explanation for the organotropic effects of this carcinogen in liver and colon and the current report provides a mechanism for the induction of kidney tumors as well as another possible means for production of liver tumors.