Indoxyl sulfate and 3-carboxy-4-methyl-5-propyl-2-furanpropionic acid (furancarboxylic acid) in serum and equilibrated peritoneal dialysate from 20 uremic patients on continuous ambulatory peritoneal dialysis (CAPD) and 23 uremic patients on maintenance hemodialysis (HD) were analyzed by high-performance liquid chromatography.
Serum levels of indoxyl sulfate and furancarboxylic acid in CAPD patients, 2.03±1.22 (mean±SD)mg/dl and 1.31±0.69 (mean±SD)mg/dl, respectively, were about 40 and about 4 times as high as in healthy subjects.
The amounts of indoxyl sulfate and furancarboxylic acid removed by CAPD and transferred into the equilibrated peritoneal dialysate were 30.2±39.2 (mean±SD)mg/day and 1.13±0.42 (mean±SD)mg/day, respectively.
On the other hand serum levels of indoxyl sulfate and furancarboxylic acid in HD patients (pre-HD: 2.76±1.65 (mean±SD)mg/dl and 4.10±1.83 (mean±SD)mg/dl, respectively, and post-HD: 2.27±1.25 (mean±SD)mg/dl and 4.83±2.13 (mean±SD)mg/dl, respectively) were markedly higher than those in healthy subjects. Rates of reduction of indoxyl sulfate and furancarboxylic acid were 17.8% and -18.0%, respectively.
These results indicate that the serum level of furancarboxylic acid in CAPD patients was significantly lower than that in HD patients, owing to removal of furancarboxylic acid by CAPD associated with transfer of albumin into the peritoneal dialysate. The serum level of indoxyl sulfate in CAPD patients was not significantly different from that in HD patients.

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Continuous ambulatory peritoneal dialysis (CAPD) is now being accepted as a treatment for end-stage renal disease (ESRD). Since diabetic patients often have systemic complications, CAPD should be recommended as a treatment rather than hemodialysis. A number of diabetics are, however, excluded from CAPD because of technical difficulties due to concomitant complications, such as visual disturbance, muscle weakness, and incomprehension of the practice of CAPD, especially in the elderly.
An ultraviolet germicidal CAPD exchange device (UV-XD) has been developed, which disinfects the spike and outlet of the dialysate bag before spike insertion, and insertion or extraction of the spike is performed with a mechanical lever.
From 1987, 5 diabetic ESRD patients were introduced to CAPD therapy using UV-XD. During a treatment period of 80.3 patient·months no peritonitis was observed in these patients, while four episodes of peritonitis occurred in 18 patients using the conventional manual exchange technique during 105.6 patient·months. Although no statistically significant difference was found in the cumulative probability of peritonitis by Kaplan-Meier's method between the two groups, the usefulness of UV-XD was recognized for patients who were not able to perform CAPD previously.
We expect an increase in CAPD therapy in diabetic patients with ESRD by means of UV-XD.

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The present study was undertaken to evaluate the effects and toxicity of vitamin C supplementation (VCS) in 61 clinically stable hemodialysis outpatients.
All patients were given VC, 500mg daily, for 2 years and observed for a further 2 years without VCS. VCS significantly increased plasma levels of ascorbic acid up to 7.8mg/dl (mean 3.3±0.4 SEM) which fell after withdrawal to within the normal range (mean 1.2±0.2mg/dl). Hyperoxalemia was aggravated by VCS (mean 61.5±3.3μmol/l, range 33.3 to 165.5) while plasma oxalate levels in the unsupplemented period decreased to 36.3±3.3μmol/l, (p<0.01). There was no difference in creatinine, hematocrit, blood transfusion requirement, morbidity (including hospitalisation) or mortality between the two periods of time in the same patients. In conclusion, we could not find any beneficial efects on morbidity or mortality as a result of using VCS in stable hemodialysis outpatients, however, secondary hyperoxalemia was aggravated. As a result of these observations it appears that VCS is harmful and unnecessary in these patients provided they are on an adequate diet.

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β₂-microglobulin (β₂-MG) production by the peripheral blood mononuclear cells (PBMC), lymphocytes and monocytes of hemodialysis (HD) patients was compared in vitro with that of healthy individuals.
In cultures of up to 96 hours, the levels of spontaneous production of β₂-MG by PBMC, lymphocytes and monocytes were not significantly different in the two groups.
However, the amount of β₂-MG produced by the PBMC of HD patients stimulated for 96 hours in culture by 10μg of phytohemagglutinin-P (PHA-P) per ml was significantly less than that of healthy individuals (p<0.005). In HD patients with a serum β₂-MG level of more than 60mg, the β₂-MG production by PBMC induced by 100 JRU of IFN-γ per ml was significantly less than that of the control group (p<0.05). Therefore, the amounts of β₂-MG produced by the lymphocytes and monocytes of HD patients with a serum level of more than 60mg/l was investigated with the use of a serum-free medium. β₂-MG production by both the lymphocytes and monocytes stimulated by 100 JRU of IFN-γ perml was decreased. However, the uptake of ³H-TdR by the IFN-γ treated PBMC did not change compared with the control group.
These findings suggest that the PBMC of HD patients have some abnormal cellular response to IFN-γ and PHA-P. In addition, the β₂-MG itself might be a mixture of free β₂-MG, modified β₂-MG and HLA-associated β₂-MG. Therefore it is important to determine the precise ratio of each type of β₂-MG in the serum and culture supernatant.

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