Clinical and Doppler ultrasonography data of a polyurethane vascular access graft for haemodialysis: a prospective study.

BACKGROUND: Absence of a permanent vascular access in most patients starting haemodialysis remains a cause of high morbidity and costs. This study obtained new clinical and colour Doppler ultrasound (CDU) data of a polyurethane vascular access graft (PVAG) proposing early post-operative cannulation. METHODS: Baseline characteristics were determined in 15 patients and the PVAGs were evaluated prospectively including first cannulation, patency and complications. CDU was used post-operatively and after 1 year for assessing graft morphology and access blood flow. RESULTS: PVAGs were cannulated at a median of 4 days post-operatively. The 1-year primary patency of the PVAG was 66.7%. During the 15 months observation three grafts thrombosed, one was replaced because of infection and one because of ischaemia. CDU measurements at the feeding brachial artery revealed a mean initial access volume flow of 773+/-89 ml/min, being significantly higher in patients without thrombosis compared to patients with thrombotic events (930+/-90 vs 375+/-143 ml/min, P<0.05). The initial inability to directly monitor PVAGs by CDU changed at sites of frequent centesis, where Doppler signals and luminal morphology could be evaluated in the follow up examination. CONCLUSIONS: The PVAG offers early access for urgent haemodialysis. CDU for access volume flow measurement at the feeding brachial artery contributes to predict access thrombosis. Direct non-invasive graft imaging is limited and the ultrasonographical changes in the polyurethane material enabling graft monitoring after repeated cannulation might indicate an injury of the graft with increased risk for access failure.

Regulation of glucose transporters in human peritoneal mesothelial cells.

BACKGROUND: Risk factors for peritoneal fibrosis and mesothelial cell (MsC) injury in CAPD are infections and bioincompatibility of the dialysate, including high glucose concentrations. To study a potential link between dialysate and glucose toxicity in MsC, we investigated the expression of facilitative glucose transporters (GLUT), which could contribute to glucose toxicity. METHODS: After induction of cell differentiation, MsC were incubated in regular medium or medium with 60 mM D-glucose, 30 mM glucose plus 30 mM mannitol, 60 mM mannitol, PD effluent, or with a cytokine mix. Expression of GLUT1, GLUT3, SGLT and GAPDH/L32 was studied by RNase protection assay. MsC were incubated under identical conditions with 14C-fluoro-deoxy-glucose for 30 minutes and glucose uptake was measured. To estimate Vmax and Km, 14C-fluoro-deoxy-glucose uptake rates were determined over a range of 0.6 to 10 mM unlabeled glucose. RESULTS: The cytokine mix significantly stimulated GLUT1 expression (3-fold) and GLUT3 (1.7-fold). There was a 1.4-fold increase in GLUT1 (p<0.05) and a 1.7-fold increase in GLUT3 (p<0.05) after incubation in high glucose but not in mannitol or PD-effluent controls. Glucose uptake studies confirmed this increase after incubation in 30 mM (p<0.05) and 60 mM glucose solutions. Kinetic studies showed the Km was approximately 3.7 mM for this transport. CONCLUSIONS: GLUT mRNA expression and glucose uptake are induced by high ambient glucose concentrations and cytokines. Unlike many other cells, MsC are not able to protect themselves from increased glucose concentrations by downregulation of GLUTs. The intracellular glucose concentration may therefore increase during CAPD, affecting growth factor expression and glycosylation, and contributing to glucose toxicity.