Correlation Study of Toxicity of Substituted Phenols to River Bacteria and Their Biodegradability in River Water

To study the correlation of toxicity with biodegradability （BODT） in order to promote QSBR development and understand the degradation mechanism. Methods Toxicity of substituted phenols to river bacteria was determined by the turbidities that were measured using a spectrophotometer （UV-190） at 530 nm against a blank control. The biodegradability of substituted phenols was expressed as BODT and the DO concentrations were determined by the iodometric titration method. Results The BODT and toxicity（log 1/IC50） of 12 substituted phenols to bacteria from the Songhua River were determined respectively. The correlation of biodegradability with toxicity was developed： BODT=8.21 （±2.22） pKa -32.44 （±8.28） log 1/IC50 ＋89.04 （±38.20）, n=12, R^2=0.791, R^2（adj）=0.745, SE=9.134, F=17.066, P=0.001. Conclusion The BODT of substituted phenols was influenced by their toxicity and the ionization constant pKa. The stronger the toxicity, the less readily the compound was degraded by river bacteria.

Ganoderma triterpenes slow cyst growth in polycystic kidney disease

OBJECTIVE Autosomal dominant polycystic kidney disease(ADPKD)is a common inherited disease with a high morbidity around 1/1000-1/400,characterized by progressive enlargement of fluid-fil ed cysts derived from renal tubular epithelial cells.Massive cysts gradually compress renal parenchyma destroying normal renal structures and compromising renal functions.Unfortunately,it will cause end-stage renal disease in most of the patients but without effective therapy now,who have to live on hemodialysis or kidney transplantation.Based on this present situation,it is of great significance to find early intervention to inhibit renal cyst development.The projective of this study was to investigate whether Ganoderma triterpenes(GT)can inhibit renal cyst development and study the related mechanism.METHODS and RESULTS First,we used MDCK cyst model,cultivated MDCK cells in vitro to form fluid-filled cysts surrounded by monolayer cells.GT inhibited MDCK cyst formation significantly,and inhibited cyst enlargement dose-dependently proving GT cyst inhibition in vitro.Then we used an embryonic kidney cyst model,wile-type mice kidneys were taken out on embryonic day 13.5 to form renal cysts stimulated with 8-Br-c AMP.GT inhibited embryonic kidney cyst development significantly in a dosedependent and reversible manner proving GT cyst inhibition at organ level.Furthermore,we used two ADPKD mouse models with severe cystic kidney disease phenotypes.GT dramatically inhibited renal cyst development,decreased ADPKD mouse kidney volume and the cyst index inside proving GT cyst inhibition in vivo.By Western blot,we proved GT down-regulated Ras/MAPK signal pathway without detectable effect on m TOR signal pathway both in MDCK cells and two ADPKD mouse kidneys.CONCLUSION GT retard renal cyst development both in vitro and in vivo significantly.The related mechanisms were involved in GT promoting renal tubular epithelial cell differentiation,down-regulating intracellular c AMP level and Ras/MAPK signal pathway.