Objective To study the drifting law of floats and potential risks of Oncomelania hupensis diffusion in the water diversion rivers of the east route of South?to?North Water Diversion Project. Methods The O. hupensis snails in the river chan?nels were monitored by the salvage method and snail luring method with rice straw curtains,and the diffusion possibility of snails along with water was assessed through the drift test of floats with GPS. Results In the flood seasons from 2006 to 2013, totally 8 338.0 kg of floats were salvaged,and 2 100 rice straw curtains were put into water in the Li Canal and Jinbao shipping channel,but no Oncomelania snails were found. The drift test of floats with GPS before water diversion showed that the flow ve?locity on water surface(northbound)was 0.45 m/s,the average drift velocity of the floats was 0.56-0.60 m/s,and the average drift distances each time were 999.70- 1 995.50 m in the Gaoshui River section,while there were no obvious drift in Jinbao shipping channel section. During the water diversion period,the flow velocity on water surface(northbound)was 0.45 m/s,the average drift velocity of the floats was 0.35-0.41m/s,and the average drift distances each time were 1 248.06-1 289.44 m in the Gaoshui River,while in Jinbao shipping channel section,the flow velocity on water surface was 0.28 m/s,the average drift velocity of the floats was 0.25- 0.27 m/s,and the average drift distances each time were 477.76- 496.38 m. The drift test showed that the floats gradually closed to the river bank as affected by water flow,wind direction and ship waves,when blocked by the reeds,water plants or other obstacles,and they would stopped and could not continue to drift without outside help. Con?clusions There are no Oncomelania snails found in the river channels of the east route of South?to?North Water Diversion Proj?ect. The drifting distance of the floating debris along with the water is restricted by the flow rate and shore environment.

OBJECTIVETo evaluate the roles of folic acid and beta-carotene in the chemoprevention of gastric and other gastrointestinal (GI) cancers.

METHODSIn a randomized, double-blind, placebo-controlled trial, a total of 216 patients with atrophic gastritis were randomly assigned to one of the four groups: (1) folate (FA, 20 mg per day plus vitamin B(12) 1 mg, intramuscularly, per month for one year, then 20 mg two times a week plus 1 mg per three months for the next year); (2) natural beta-carotene (N-betaC, 30 mg per day for first year, then 30 mg two times a week for the next); (3) synthetic beta-carotene (S-betaC, administered as in N-betaC); and (4) placebo. Follow-ups continued from 1994 to 2001.

RESULTSA total of 7 new cases of gastrointestinal cancers were diagnosed with 3 stomach, 1 colon and 1 esophageal cancers occurring in the placebo group; 1 stomach cancer in both of the N-betaC and S-betaC groups, and no cancer occurring in FA group. In terms of GI cancers, there was a significant reduction in the FA group, compared with the placebo group (P = 0.04). A similar trend was observed in both N-betaC and S-betaC groups (P = 0.07 - 0.08). Taken together, the three intervention groups displayed a highly significant decrease in occurrence (P = 0.004, vs placebo), and a lower risk for GI cancers (OR = 0.12; 95% confidence interval, 0.03 - 0.51). For development of gastric cancer, any one of the three active-treated groups did not reach statistically significant reduction. The FA group showed obvious improvement of the gastric mucosal lesions with more patients displaying lesions reversed or stable atrophy and inflammation (P = 0.04), reversed intestinal metaplasia (P = 0.06) at the end of follow-up, and reversed displasia (P = 0.017) at 12 months. Two cases of false jaundice were found in beta-carotene groups with no influence on administration, and no side-effects were reported in FA group.

CONCLUSIONSThis trial revealed the interventional effect of folic acid on the development of GI cancers, a similar effect of beta-carotene was also detected. Also, folic acid may be of use to treat atrophic gastritis by preventing or reversing the precancerous lesions.

Adult ; Aged ; Anticarcinogenic Agents ; therapeutic use ; Double-Blind Method ; Female ; Folic Acid ; adverse effects ; therapeutic use ; Gastric Mucosa ; pathology ; Gastrointestinal Neoplasms ; prevention & control ; Humans ; Male ; Middle Aged ; Patient Compliance ; Stomach Neoplasms ; prevention & control ; beta Carotene ; therapeutic use