Simultaneous determination of acetochlor and propisochlor residues in corn and soil by solid phase extraction and gas chromatography with electron capture detection.

A sensitive and simple method for simultaneous analysis of acetochlor and propisochlor in corn and soil has been developed. Two herbicides were extracted from soil and corn matrices with methanol/water and acetone, respectively, followed by solid phase extraction (SPE) to remove co extractives, prior to analysis by gas chromatography with electron capture detection (GC-ECD). Primary secondary amine (PSA) SPE cartridges (500 mg, 3 mL) were used for sample preparation. The analytes from corn and soil matrices were eluted with 5 mL petroleum ether-acetic ether (95/5, v/v) and 3 mL petroleum ether-acetic ether (95/5, v/v), respectively. The recoveries of two pesticides ranged from 73.8% to 115.5% with relative standard deviations (RSD) less than 11.1% and sensitivity of 0.01 mg/kg, in agreement with directives for method validation in residue analysis. The method was successfully applied to determine the fate of acetochlor and propisochlor in real corn and soil samples. For acetochlor and propisochlor, the half-life times (t1/2) in soil was 5.541 and 6.074 days, respectively. No acetochlor and propisochlor residues (<0.01 mg/kg) were detected in corn at harvest time withholding period of 2.5 months after treatments of the pesticides. Direct confirmation of the analytes in samples was achieved by gas chromatography-mass spectrometry (GC-MS).

Enhanced expression of TGF-beta 1 by peritoneal macrophages in CAPD patients.

Peritoneal macrophages are the predominant cells in peritoneal dialysate. To clarify the role of the macrophage in fibrosis of the peritoneum in long-term continuous ambulatory peritoneal dialysis (CAPD) patients, we studied the transforming growth factor beta (TGF-beta 1) mRNA expression by peritoneal macrophages from peritoneal dialysis patients. Macrophages were obtained when the catheter was inserted and one month later. TGF-beta 1 mRNA was measured by slot-blot hybridization using a cDNA probe. The result was that TGF-beta 1 expression was significantly higher in macrophages from peritoneal dialysate than that of macrophages obtained during catheter insertion. This suggests that peritoneal macrophages play a role in the pathogenesis of fibrosis of peritoneum in peritoneal dialysis patients. It also suggests that peritoneal macrophages in dialysate have been somewhat activated.

Influence of peritoneal dialysis on the progression of chronic renal failure.

To determine whether an early start of peritoneal dialysis is beneficial to the preservation of residual renal function, we studied the effect of peritoneal dialysis on the progression of glomerular sclerosis in subtotal nephrectomy rats. Four weeks after subtotal nephrectomy, Wistar rats were treated with peritoneal dialysis (PD) (through a silicone catheter, two exchanges per day with 20 mL 1.5% dextrose solution per exchange for 8 weeks, n = 10). Then the kidneys were checked. The sclerosis index was significantly lower in the PD group than that of the control group, which was 1.12 +/- 0.13, 1.64 +/- 0.19, respectively (p < 0.05). This suggests that peritoneal dialysis may suppress the progression of chronic renal failure. An early start of PD may benefit the preservation of renal function in uremic patients.