We have developed an immunological procedure for measuring advanced glycosylation end-products (AGEs) in serum. Using this method, we measured AGEs in healthy volunteers, patients with diabetes, renal failure without treatment and in patients with renal failure, treated with hemodialysis (HD) or continuous ambulatory peritoneal dialysis (CAPD). We found that AGEs were moderately elevated in diabetics without renal failure and highly elevated in CAPD and HD patients irrespective of their glycemic status. AGE levels correlated significantly with creatinine levels but not with levels of glucose or patient age or sex. AGE levels were reduced significantly post-hemodialysis. Preliminary experiments have shown that circulating AGEs have a molecular weight of approximately 1.5 to 2.0 kDa. More studies are needed to establish if AGE measurements in serum are prognostic indicators of the complications of either diabetes or renal failure.

We evaluated the effect of the various osmotic solutes on the growth rate of human mesothelial cells (HMC) in an in vitro culture. Glucose inhibited proliferation of HMC in a dose dependent way. At high glucose concentrations (60 mM, 90 mM) the effect was instant but at lower concentration (30 mM) decrease in the mesothelial cell proliferation was significant only after five days of incubation. Reversibility of the glucose effect was inversely proportional to exposure time to this solute. Mannitol and glycerol studied in similar concentrations as glucose decreased proliferation of the mesothelial cells less than glucose, whereas amino acid glycine had a similar effect to glucose. However, all osmotic solutes caused similar injury to mesothelial cells membrane as measured by release of LDH. These results suggest that the toxic effect of the osmotic solutes on proliferation of the mesothelial cells depends not only on the hyperosmolality but also on some metabolic effect(s). In an in vitro culture, HMC may provide a suitable model for the study of the toxic effect of dialysis fluid on peritoneal mesothelium.

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We studied the effect of intracellular calcium stores modulation on the ability of lymph vessels to propel fluid in a preparation of actively contracting isolated bovine mesenteric lymph vessels. Vessels were cannulated at each end, placed in a temperature-controlled organ bath, and circulated with oxygenated Krebs solution. Vessel wall tension (transmural pressure) was changed by raising the height of the fluid-filled reservoir and outflow catheters appropriately. When transmural pressure was set and maintained at 6 cmH2O (1 cmH2O = 98.1 Pa), caffeine (10(-3) M), ryanodine (10(-7) M), and cyclopiazonic acid (CPA; 7 x 10(-6) M) inhibited lymphatic pumping. We also studied the effect of these agents on the relationship between lymph pump activity and transmural pressure, a relationship normally described by a bell-shaped curve. When transmural pressure was increased at 5-min intervals, the magnitude of inhibition by caffeine (10(-3) M) and CPA (7 x 10(-6) M) was greater than when transmural pressure was held constant. Ryanodine, on the other hand, had no effect on lymphatic contractility when transmural pressure was manipulated. The ryanodine results suggest the existence of an interaction between vessel wall stretch and intracellular calcium stores modulation that is not seen with caffeine or CPA.