Glucose degradation products in peritoneal dialysis fluids may have both local and systemic effects: a study of residual fluid and mesothelial cells.

OBJECTIVE: When peritoneal dialysis (PD) fluids are heat sterilized, glucose is degraded to carbonyl compounds. These compounds are known to interfere with many cellular functions and to promote the formation of advanced glycation end-products. However, little is known about what actually happens with glucose degradation products (GDPs) after infusion into the peritoneal cavity. The aim of the present study was to investigate possible targets for GDPs in the peritoneal cavity. DESIGN: In vitro reactions between residual fluid and GDPs were studied by incubating unused PD fluid with overnight dialysate. Confluent monolayer cultures of human mesothelial cells were used as a model to study the reactions of GDPs with the cells lining the peritoneal cavity. METHODS: Samples were analyzed, using high pressure liquid chromatography, for the presence of formaldehyde, acetaldehyde, 5-hydroxymethyl-2-furaldehyde (5-HMF), methylglyoxal, and 3-deoxyglucosone (3-DG). Cytotoxicity was determined as inhibition of proliferation of cultured fibroblasts. RESULTS: None of the analyzed GDPs reacted with overnight dialysate. Formaldehyde and methylglyoxal, in contrast to 3-DG and 5-HMF, reacted with the cultured mesothelial cells. CONCLUSIONS: Low molecular weight carbonyls such as formaldehyde and methylglyoxal most probably react with the mesothelial cells lining the peritoneal cavity, and could be responsible for the disappearance of these cells during long-term treatment. 3-Deoxyglucosone showed remarkably low reactivity and was most probably transported within the patient.

3-Deoxyglucosone, a promoter of advanced glycation end products in fluids for peritoneal dialysis.

OBJECTIVE: The accumulation of irreversible formed advanced glycosylation end products (AGE) in the peritoneal cavity might play an important role in the development of ultrafiltration failure and peritoneal membrane destruction. 3-Deoxyglucosone (3-DG), more formally named 3-deoxy-D-erythro-hexos-2-ulose or 3-deoxy-D-erythro-hexosulos is known to be a potent cross-linker responsible for the polymerization of proteins and a precursor of AGE. The purpose of the present study was to determine if the dicarbonyl compound 3-DG, is formed as a glucose degradation product during heat sterilization of fluids for peritoneal dialysis (PD). DESIGN: Four fluids were examined: a commercially available PD fluid Gambrosol (Gambro, Lund, Sweden); Gambrosol-Bio (Gambro), a new PD-fluid produced under conditions that minimize the generation of toxic glucose degradation products; a fluid prepared in the laboratory by sterile-filtration; and a fluid prepared in the laboratory by heat sterilization. METHODS: The concentration of 3-DG was analyzed by measuring the concentration of its diaminonaphthalene derivative by HPLC using a Waters Symmetry C18 column. RESULTS: The 3-DG concentrations in the commercially- and laboratory-prepared heat-sterilized fluids were 118 and 154 micromol/L, respectively. Gambrosol-Bio and the sterile-filtered fluid produced in the laboratory contained 3-DG in concentrations of 12.3 and less than 1.2 micromol/L, respectively. CONCLUSION: Our results demonstrate that during the heat sterilization of conventional PD-fluids, 3-DG is produced as a degradation product of glucose. It was also demonstrated that, through an alteration of the manufacturing condition, the production of 3-DG could be considerably reduced. We speculate that the presence of 3-DG in unused conventional PD-fluid could act as a local promoter, and increase local AGE formation within the peritoneal cavity.

Cytotoxicity, pH, and glucose degradation products in four different brands of PD fluid.

This study was undertaken in order to evaluate differences in pH, cytotoxicity, and concentration of glucose degradation products between different peritoneal dialysis (PD) fluids. Four brands of commercial PD fluids were selected: Gambrosol, Bieffe, Dianeal, and Lock-olys, with a glucose concentration between 3.86% and 4.25%. The cytotoxicity of unused PD fluid was measured as inhibition of cell growth after three days' exposure of a fibroblast cell line using neutral red vital stain. The concentration of 2-furaldehyde, 5-hydroxymethyl-furaldehyde (5-HMF), acetaldehyde, formaldehyde, glyoxal, and methylglyoxal was analyzed by high-performance liquid chromatography technique. All the investigated PD fluids were cytotoxic and contained noticeable amounts of aldehydes. No major differences were observed in pH, although one fluid with a slightly lower pH was found to be less cytotoxic. This fluid also contained less formaldehyde, acetaldehyde, methylglyoxal, and glyoxal but instead contained more 5-HMF. We conclude that all brands of PD fluid are cytotoxic due to glucose degradation products and that they contain noticeable concentrations of low-molecular aldehydes. Our results also demonstrate that the concentration of 5-HMF, used as a regulatory control of PD fluids, does not correlate well with cytotoxicity.

In vitro biocompatibility of a heat-sterilized, low-toxic, and less acidic fluid for peritoneal dialysis.

OBJECTIVE: The aim of this study was to investigate a peritoneal dialysis (PD) fluid (PD-Bio), produced with the intention of reducing the amount of glucose degradation products and to increase the final pH. The heat sterilization of the fluid was performed with the glucose separated from the electrolytes. After sterilization the two solutions were combined. METHODS: The in vitro biocompatibility of PD-Bio was measured as the inhibition of cell growth of a cultured fibroblast cell line and as the stimulated release of interleukin-1 beta from cultured human mononuclear cells. The glucose degradation products were measured as UV absorbance at 228 nm or 284 nm and the concentration of aldehydes was estimated with high-performance liquid chromatography and gas chromatography. RESULTS: Our results demonstrate that in comparison to conventional PD fluids the pH of PD-Bio was increased, to about 6.5. Due to less contaminating glucose degradation products in PD-Bio, basal cytotoxicity was significantly decreased for both 1.5% and 4% glucose-containing fluids, and the stimulated release of interleukin-1 beta was normalized compared to sterile filtered controls with the same pH. UV absorbance measured at 228 nm was decreased, whereas the absorbance at 284 nm was equal to that of a conventional fluid. In PD-Bio the concentrations of formaldehyde, acetaldehyde, methylglyoxal, and 2-furaldehyde were found to be below the detection limit, whereas glyoxal was present in the same and 5-hydroxymethylfurfural (5-HMF) in higher concentrations than in conventionally produced PD fluid. CONCLUSIONS: The results demonstrate that it is possible to improve biocompatibility of PD fluids by simply changing the way the fluid is produced.