Li-Qing Wang

Pectin-Supplemented Enteral Diet Reduces the Severity of Methotrexate-Induced Enterocolitis in Rats

BACKGROUND Administration of methotrexate (MTX) to rats fed an elemental diet results in a high mortality from severe enterocolitis. Previous studies have shown that pectin is an important precursor of substrates for intestinal structure and function and may facilitate intestinal recovery after enterocolitis. The aim of this study is to evaluate the effect of pectin on MTX-induced enterocolitis in rats. METHODS Rats received intragastric infusion of either 1% pectin-supplemented or pectin-free elemental diet from the beginning of the study via a gastrostomy. On the 4th day animals received either MTX, 20 mg/kg intraperitoneally, or saline injection and were killed on the 7th day for sampling. RESULTS Pectin supplementation significantly decreased body weight loss, organ water content, and intestinal myeloperoxidase levels and increased mucosal protein, DNA, and RNA content in enterocolitis rats. The intestinal permeability was increased by administration of MTX, and pectin supplementation significantly reversed the increased permeability in the distal small bowel and colon. Pectin supplementation also lowered the magnitude of bacterial translocation, decreased plasma endotoxin levels, and restored bowel microecology. CONCLUSIONS Pectin significantly decreased MTX-induced intestinal injury and improved bowel integrity.

Experimental foreign-body infection in the biliary tract in rats.

BACKGROUND Biomaterials used for biliary drainage may potentially result in biomaterial-associated infections. METHODS Foreign-body infection in the biliary tract was investigated in rats. Rubber drain pieces were implanted in the biliary tract in rats for 1-4 weeks, followed by challenges with 10(2) to 10(4) colony-forming units (cfu) Escherichia coli injected into the common bile duct. The rate of infection was calculated, the bacterial growth in the biliary tract was observed over 72 h after challenges, and the opsonic activity in bile and in sera was assessed. RESULTS In the group with drain material, inocula as small as 10(2) cfu produced persisting infection in the common bile duct in 90% of animals, whereas the same number of E. coli infected only 30% of rats in the control and sham implantation groups (p < 0.01, chi-square test). Complement-mediated opsonic activity in bile of animals with implanted drain pieces gradually decreased with time, whereas opsonic activity in sera from the same animals remained unchanged. CONCLUSIONS Implants in the biliary tract impair local host defense, resulting in an increased susceptibility to microbial infection.

Reduction of E. coli adherence to rubber slices treated with phospholipids

The present study aimed at modifying the surface of biliary drain material to reduce bacterial adherence. The adherence of cells of seven E. coli strains to rubber slices treated with phosphatidylcholin (PC) or phosphatidylinositol (PI) and the adherence of cells of E. coli strain NG7C to PC‐ or PI‐treated rubber slices implanted in the common bile duct in rats were studied in vitro. The rubber slices were incubated with 1 times 107 cfu radiolabeled E. coli cells/ml at 37°C for 60 min and then drained and washed thrice in 2 ml PBS, and adherent E. coli cells were quantified by radioactivity counting. The results show that both PC and PI absorbed on the surface of slices reduced the adherence of E. coli cells in at least two ways, i.e. by changing surface properties in vitro and by reducing deposition of host‐derived molecules on phospholipid‐treated surfaces in vivo. The results may be of use for modification of the biomaterial surface in the clinical situation.

COLLATERAL FORMATION AFTER REPEATED TRANSIENT DEARTERIALIZATION OF THE RAT LIVER

Hepatic artery ligation is used for the palliation of patients with malignant liver tumours. Collaterals are developed rapidly and could to some extent explain why the growth is affected for only a short period. With intermittent dearterialization, collaterals seem to be avoided and possibly a more extended effect should be expected. The most efficient period of dearterialization to avoid collaterals was studied in this experiment. Five groups of rats were treated with daily repeated transient dearterializations for 0 (n = 3), 60 (n = 6), 120 (n = 6), 180 (n = 6) and 240 minutes (n = 6) respectively for 5 days and compared to another group (n = 3) that was permanently dearterialized. After treatment, celiac angiograms were obtained. All hepatic arteries were reliably occluded and patent after 5 days of daily blockades in all but two rats. There were no collaterals demonstrable on the angiograms in the first four groups after 5 days of intermittent obstruction of the arterial blood flow to the liver. After 240 minutes of dearterialization as well as after collaterals developed and were clearly demonstrated on the angiograms after six days. Liver enzymes were normal even after 4 hours of dearterialization. Repeated occlusions of the hepatic artery was reliably achieved with the implantable minioccluder. Repeated, transient dearterializations for 1, 2 or 3 hours could be performed without development of collaterals and without damage to the liver.

The Influence of Portal Deviation on the Effect of Repeat Dearterializations of a Transplantable Adenocarcinoma to the Rat Liver

As liver tumours receive some of their blood supply from the portal vein, we wanted to illustrate the influence of portal blood flow in combination with dearterialization in the treatment of liver tumours. Forty male, inbred Wistar/Furth rats with an adenocarcinoma transplanted to the liver were treated with various inflow occlusions repeated daily for 5 days. Deviation of the portal blood flow alone with an end-side porto-caval shunt did not alter the tumour growth (p = 0.089). Thirty min of repeat dearterializations was potentiated by portal deviation so that tumour growth was delayed (p = 0.004). However, repeat dearterializations for 60 min in portal deviated rats induced irreversible liver damage and all rats died in a few days. Repeated dearterializations for 60 minutes alone retarded the tumour growth as efficiently (p = 0.007). Simultaneous occlusion of the hepatic artery and the portal vein for 30 minutes with a side-side porto-caval shunted (total devascularization) did not affect tumour growth (p = 0.154). Liver aminotransferases (ASAT and ALAT) were substantially increased following dearterialization for 30 min in rats with either an end-side or a side-side porto-caval shunt. Dearterialization for 60 min in rats with end-side porto-caval shunts gave a further release of ASAT and ALAT. In conclusion, portal deviation did not augment the therapeutic benefit of repeat dearterializations for the treatment of this experimental liver tumour. Repeat dearterializations alone seemed to be a feasible and efficient therapy for liver tumours.