Determination of 17-hydroxycorticosteroids in dialysate solution as a measure of adrenocortical function in hemodialysis patients

Dialysate contents of 17-hydroxycorticosteroids (17-OHCS) in hemodialysis patients were studied as a potential measure of adrenocortical function. Dialysate 17-OHCS contents after a 2-day interval of hemodialysis in 15 hemodialysis patients were determined. Dialysate 17-OHCS increased after intravenous injection of cortisol the evening prior to hemodialysis (n = 4). Dialysate 17-OHCS content was suppressed, as was plasma cortisol, after a standard dexamethasone (Dex) suppression test (n = 1). Their plasma cortisol was suppressible or nonsuppressible by an overnight Dex suppression test, as reported previously. However, basal dialysate 17-OHCS contents were not different between them, indicating that the nonsuppressible patients with overnight Dex seem not to have hypercortisolism. We conclude that determination of dialysate 17-OHCS seems a useful noninvasive technique for the evaluation of adrenocortical function in hemodialysis patients.

Peritoneal dialysis solution pH and Ca2+ concentration regulate peritoneal macrophage and mesothelial cell activation

We evaluated the in vitro effects of pH and Ca2+ concentration of peritoneal dialysis solution (PDS) on (1) the release of interleukin-1 (IL-1), tumor necrosis factor alpha (TNF-alpha), interleukin-6 (IL-6), and interleukin-8 (IL-8) from peritoneal macrophages (PM0) and peritoneal mesothelial cells (PMC); (2) the release of IL-6 and IL-8 by PMC; and (3) the PM0 and PMC intracellular Ca2+ concentration. Aliquots of 5 x 10(6) PM0 and PMC were incubated (2 hr, 37 degrees C) in 1 ml of physiologic growth medium (RPMI 1640) and in 1 ml of four different PDS (1.36 g/dl glucose): (1) type A PDS (pH 5.5, Ca2+ 1.75 mM), (2) type B PDS (pH 5.5, Ca2+ 1.25 mM), (3) type C PDS (bicarbonate buffered pH 7.4, Ca2+ 1.75 mmol/L, and (4) type D PDS (bicarbonate buffered pH 7.4, Ca2+ 1.25 mM); each was stimulated with S. epidermidis. Results showed that type A PDS samples induced an average 60% increase in PM0 and PMC cytoplasmic levels and in cytokine release, whereas with type B PDS samples there was a 90% decrease. Type C PDS samples did not modify the PM0 and PMC IL-6 and IL-8 production, whereas a 3-fold rise in the production of IL-1 and TNF-alpha by PM0 was seen; this was associated with an increase in PM0 and PMC Ca2+ cytoplasmic levels. When type D PDS samples were incubated, however, there was an average 40% decrease in PM0 and PMC cytoplasmic Ca2+ levels and in cytokine release.(ABSTRACT TRUNCATED AT 250 WORDS)

Citrate anticoagulation and divalent cations in hemodialysis

Anticoagulation with citrate in combination with a calcium-free, magnesium-containing dialysate (Ca-Mg+) and intravenous supplementation of calcium is a safe procedure in renal failure patients at high risk of bleeding. Since magnesium may antagonize the anticoagulant effect of citrate by forming complexes with citrate, we studied the in vitro and in vivo interactions of calcium and magnesium on citrate anticoagulation. In the in vitro studies the activated partial thromboplastin time (APTT) was 88 s, both after addition of 3.0 mumol magnesium and after addition of 1.0 mumol calcium. The combination of 2.4 mumol magnesium and 1.0 mumol calcium achieved similar APTT values of about 35 s as 3.5 mumol calcium alone. Moreover, in a Lee-White blood clotting time, the anticoagulant effect of 7 mumol citrate was neutralized by either 10.5 mumol of a mixture of the two cations or 10.5 mumol calcium chloride alone. In 6 chronic hemodialysis patients the in vivo interactions of calcium and magnesium on citrate were measured. At the dialyzer outlet, the whole blood activated clotting time (ACT) was significantly (p < 0.05) shorter during dialysis with a Ca-Mg+ dialysate than during dialysis with a calcium- and magnesium-free dialysate (Ca-Mg-). With the Ca-Mg- dialysate the ACT at the dialyzer outlet was still significantly longer than the ACT in the arterial line before citrate infusion. We also compared the serum concentrations of calcium and magnesium during the Ca-Mg- dialysate which was used in combination with intravenous calcium and magnesium supplementation - 0.18 and 0.08 mmol/min respectively--and during a conventional calcium- and magnesium-containing dialysate (Ca+Mg+).(ABSTRACT TRUNCATED AT 250 WORDS)

In vitro effects of amino-acid-based versus glucose-based continuous ambulatory peritoneal dialysis fluids on peritoneal macrophage function

We studied the in vitro effects of peritoneal dialysis fluids (PDF) containing 1 and 1.5% amino acids (AA) as compared to approximately equiosmolar glucose (GLU)-based PDF (1.5 and 4.25%) and control buffer, respectively, on peritoneal macrophage (PMO) function. The media were tested at original pH (5.3-5.5) and after pH adjustment to 7.4. PMO were isolated from the effluents of 10 on continuous ambulatory peritoneal dialysis (CAPD) patients and tested for luminol- and lucigenin-enhanced chemiluminescence (CL), superoxide generation measured by cytochrome c reduction, killing capacity and phagocytosis after incubation (30 min, 37 degrees C) in the PDF used. All AA-based PDF exhibited a statistically significant depressive effect on integral CL response, O2- production and bacterial killing of PMO at pH 7.4 in comparison with pH-adjusted GLU-based PDF of similar osmolality and buffer. Exposure of PMO to acidic AA-based media did not result in a significantly different suppression of the oxidative metabolism and the killing capacity as compared to fresh GLU-based fluids. Phagocytosis of PMO did not show significant differences after incubation in the solutions studied. Thus, the AA-based PDF employed compromise the oxidative metabolism and the killing capacity of PMO at pH 7.4 in vitro significantly more than GLU-based fluids. Since pH-identical and almost equiosmolar PDF were compared, the specific composition of the AA-based fluids, especially the high content of lactate and several essential AA, could be responsible for this detrimental impact.

On-line monitoring of urea in effluent liquid during haemodialysis

An analytical system specially built for on-line urea monitoring is reported. Measurements are carried out in the effluent of a haemodialysis machine. The measuring system employs the dialyser inflow stream as a carrier solution channel in a continuous fashion. The analyser periodically samples the outflow stream of the dialyser by means of an automatic injection valve. The analyser features a bioreactor consisting of immobilized urease and a gas-diffusion module. It is through this module that the urea is converted to ammonia gas which is transferred to another carrier channel, this transports the ammonium ion to a tubular, all-solid-state, ion-sensitive electrode. A timer controls the transport, injection, the measuring and the recording subsystems. The analyser has been used during actual haemodialysis sessions. Urea clearances were also measured in batch, using conventional spectrophotometric clinical equipment. The correlation between both methodologies was sufficient to confirm the usefulness of the developed on-line analyser to monitor the optimal length of haemodialysis sessions.

Aplastic osteodystrophy without aluminum: the role of "suppressed" parathyroid function

We evaluated 259 dialysis patients using serum parathyroid hormone (PTH, IRMA; normal range 1 to 5.5 pM or 10 to 55 pg/ml), the deferoxamine infusion test and iliac crest bone biopsy to determine the various forms of renal osteodystrophy and their risk factors. Although half of the biopsied patients had low turnover osteodystrophy, evidence of aluminum toxicity was present in only 1/3 of them. Additional risk factors for this bone lesion included treatment with peritoneal dialysis, ingestion of calcium carbonate, diabetes mellitus and advanced age. The PTH levels in patients with the aplastic lesion were significantly lower than in patients with normal or high bone turnover lesions [7.7 +/- 6.1 vs. 36.9 +/- 3.2 pM (77 +/- 61 vs. 369 +/- 32 pg/ml), P < 0.0001]. Aside from hypercalcemia, these patients were relatively asymptomatic. In a second study, 10 patients on peritoneal dialysis with the aplastic lesion had their dialysate calcium lowered from 1.62 to 1.0 mM. This resulted in a significant increase in PTH levels, from [3.7 +/- 0.8 to 10.6 +/- 1.9 pM (37 +/- 8 to 106 +/- 19 pg/ml), P < 0.001] which persisted over the nine-month observation period. In conclusion, the aplastic lesion is the most common form of renal osteodystrophy, with aluminum intoxication implicated in only 1/3 of the cases. In the remainder, factors identified include therapy with peritoneal dialysis using supraphysiological dialysate calcium, oral CaCO3 intake and diabetes mellitus.(ABSTRACT TRUNCATED AT 250 WORDS)

The requirement of low calcium dialysate in patients on continuous ambulatory peritoneal dialysis receiving calcium carbonate as a phosphate binder

In the present study we investigated the requirement of low calcium dialysate in 35 patients on continuous ambulatory peritoneal dialysis (CAPD) receiving calcium carbonate as the sole phosphate binder over a 12-month period. Patients with corrected serum calcium > or = 2.85 mmol/L after switching to oral calcium carbonate were given 1 to 3 2-litre exchanges of 2.5 mEq/L calcium dialysate. Serum phosphate level dropped from the pretreatment value of 2.95 +/- 0.62 to a level of between 1.70 +/- 0.41 to 2.03 +/- 0.44 mmol/L 2 weeks after therapy. Corrected serum calcium level increased significantly from 2 weeks onwards. Serum alkaline phosphatase rose initially at 2 and 6 weeks and decreased from 3 months onwards. Serum parathyroid hormone level dropped significantly from a mean pretreatment level of 569 to 320 pg/ml after 12 months (p < 0.001). Serum aluminum decreased significantly from a mean of 1.04 to 0.65 umol/L (p < 0.01). Daily calcium carbonate requirement fluctuated but tended to increase till 8 months and plateaued and ranged from 2.61 +/- 0.57 to 3.98 +/- 2.11 gm. The daily requirement of low calcium dialysate followed a similar trend with approximately three-quarters of patients ultimately requiring at least 1 bag of low calcium dialysate. Eight patients did not require low calcium dialysate. Patients who required low calcium dialysate were significantly older, had a significantly lower pretreatment serum parathyroid hormone and higher serum aluminum levels than those who did not.(ABSTRACT TRUNCATED AT 250 WORDS)

Improvement of severe secondary hyperparathyroidism in dialysis patients by intravenous 1 alpha(OH) vitamin D3, oral CaCO3 and low dialysate calcium

Seventeen patients (9 men, 8 women; aged 27 to 75 years) who were on chronic hemodialysis for 1 to 14 years were included in the study because they had severe hyperparathyroidism diagnosed by elevated plasma alkaline phosphatase and on plasma intact PTH levels more than twice the upper limit of normal. They had been previously treated with various combinations of oral calcium and/or Al(OH)3 as phosphate binders, oral 1 alpha(OH) vitamin D3 metabolites and a dialysate calcium concentration (DCa) of 1.6 to 1.75 mmol/liter. When i.v. alpha calcidol was introduced DCa was reduced to 1.25 mmol/liter and CaCO3 taken with the meal was used as the sole phosphate binder. alpha calcidol was i.v. injected after the third dialysis of the week at a dose up to 4 micrograms per dialysis in order to obtain a predialysis plasma concentration of Ca at 2.5 +/- 0.2 and PO4 between 1.5 and 2 mmol/liter. All the other treatments were discontinued. During the six months of follow-up, the mean weekly dose of alpha calcidol was 6 micrograms and CaCO3 700 +/- 50 mmol. Plasma calcium (PCa) increased moderately from 2.35 to 2.47 mmol/liter (P < 0.05) whereas plasma PO4 (PPO4) did not significantly increase (1.56/1.64 mmol/liter). Total alkaline phosphatase and its bone isoenzyme activity decreased significantly to normal values [respectively from 186 to 83 IU (normal: 135) and from 102 to 32 IU (normal < 33)] whereas plasma intact PTH decreased from 485 to 125 pg/ml (normal < 55).(ABSTRACT TRUNCATED AT 250 WORDS)

Beta 2-microglobulin generation and removal in long slow and short fast hemodialysis

We studied the influence of different modes of hemodialysis (HD) on plasma levels of beta 2-microglobulin (P-beta 2-m) and its correlation to changes in leukocyte count, complement activation (C3a), and elastase generation. The influence of dialyzer membrane, membrane surface area, duration of treatment, and blood flow was analyzed with respect to post-HD levels of P-beta 2-m. Twenty patients underwent 12 modes of bicarbonate hemodialysis in random order (n = 252) using three different membranes (Cuprophan [CU], hemophan [HE], or polyamide [PA], two dialyzer areas, and fast (400 mL/min) or slow (200 mL/min) blood flow (Qb) for 2 or 4 hours, respectively. All dialysate was collected and beta 2-m was analyzed (D-beta 2-m). After correction for hemoconcentration, P-beta 2-m concentrations were found to have decreased significantly during treatment with all three membranes (CU, 0.9 +/- 0.3 mg/L, P = 0.002; HE, 1.2 +/- 0.3 mg/L, P < 0.001; and PA, 8.3 +/- 0.3 mg/L, P < 0.001). Elimination of P-beta 2-m was influenced by type of membrane (P < 0.001) and ultrafiltration volume (P = 0.0019) but not by membrane area or Qb. The largest reduction in P-beta 2-m (-10.4 mg/L) was achieved by the following treatment combination: PA membrane, large dialyzer area, and low Qb for 4 hours. P-beta 2-m decreased more during PA dialysis at low Qb for 4 hours (-9.9 +/- 0.5 mg/L) than during high Qb for 2 hours (-6.8 +/- 0.5 mg/L, P < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Detection of low molecular size lipopolysaccharide contaminated in dialysates used for hemodialysis therapy with polyacrylamide gel electrophoresis in the presence of sodium deoxycholate

Dialysis membranes are generally considered to be impermeable for bacterial endotoxin (lipopolysaccharide, LPS) contaminated in dialysates used for hemodialysis therapy, since LPS molecular size in aqueous media has been reported to be more than 10(6). However, there are few reports concerning its size in dialysates. We have already presented a newly developed polyacrylamide gel electrophoresis with sodium deoxycholate (DOC-PAGE) which proves the LPS size. Using this method, therefore, we attempted to clarify the size of LPS in dialysates. We demonstrated that LPS in dialysates had roughly two different molecular sizes with DOC-PAGE and that compared to migration profiles of Salmonella LPS as controls on DOC-PAGE, one molecular size of LPS was approximately 4,000 and the other in tens of thousands. This investigation indicates the possibility of LPS transfer across dialysis membranes.

Biocompatibility of a glucose-polymer-containing peritoneal dialysis fluid

The currently available glucose-containing peritoneal dialysis fluids (PDF), which are all hyperosmolar, are toxic to the cells present in the peritoneal cavity. However, glucose-polymer solutions, being isosmolar, may have improved biocompatibility in this respect. We therefore compared in vitro the effects of PDF containing glucose-polymers with that of glucose solutions on the function of donor granulocytes and monocytes (MN), and on the viability of mesothelial cells. In addition, the function of peritoneal macrophages (PMO) of eight patients was studied in a randomized cross-over setting following intraperitoneal exposure to glucose-polymer-versus glucose-monomer-containing fluid of comparable ultrafiltration capacity. Donor granulocytes, as well as MN, showed significantly better phagocytosis of both Staphylococcus epidermidis and Escherichia coli after incubation in the glucose-polymer solution as compared with the 3.86% glucose-containing fluid. Their oxidative metabolism, as measured by chemiluminescence, also showed that the glucose-polymer solution was less inhibitory than fluids containing 2.27 or 3.86% glucose. Patient-derived PMO showed a significantly better phagocytic capacity for S epidermidis and E coli, a significantly higher killing of E coli, and a significantly higher chemiluminescence response after intraperitoneal exposure to the glucose-polymer solution as compared with the glucose-monomer-based fluid. Increasing the osmolality of the glucose-polymer solution to that of the respective glucose solutions blunted the favorable effect on phagocyte function, suggesting the beneficial effect to be osmolality-mediated. However, no major difference was observed between the glucose-polymer solution and the glucose-based fluid in their effects on mesothelial viability.(ABSTRACT TRUNCATED AT 250 WORDS)

Choline levels in human peritoneal dialysate

The average free choline level was determined to be 14 mumol/L in peritoneal dialysates and 22 mumol/L in the plasma of 30 patients on continuous ambulatory peritoneal dialysis (CAPD). Daily choline loss via dialysate averaged 129 mumol with 32 mumol choline lost per dwell. Daily choline loss via the dialysate was positively correlated with plasma choline concentrations. Choline levels in dialysate during CAPD exceed plasma levels of choline 9 mumol/L in healthy individuals.

Ultrafiltration failure and dialysate glucose in CAPD

This study was performed to evaluate the use of the glucose concentration versus glucose absorption in the dialysate to estimate ultrafiltration efficacy. In 26 patients (16 men, 10 women) on continuous ambulatory peritoneal dialysis, a total of 128 dwells were investigated. Each dwell lasted 5 hours, using 2 L of peritoneal dialysis fluid containing 140 mmol/L glucose. After the dwell, the removed peritoneal dialysis fluid was weighted. The concentrations of creatinine and glucose and the total amount of glucose were analyzed. The mean concentration of dialysate glucose for the whole group after a 5-hour dwell was 38.9 +/- 8.9 (SD) mmol/L. The ultrafiltration volume was inversely correlated to the glucose absorbed (r = -0.59, p = 0.002), but was not significantly correlated to the glucose concentration in the dialysate (r = 0.40, p = 0.057). The ultrafiltration volume was not related to the creatinine concentration in the dialysate or the body weight. The average dialysate glucose did not change during a one-year observation time. Patients with diabetes mellitus had significantly lower glucose absorption than nondiabetics (p = 0.045), and patients with low ultrafiltration efficacy had significantly greater glucose absorption than those with normal and high ultrafiltration (p = 0.038). There was no difference between those who had those who had not suffered from peritonitis. The results indicate that the glucose absorption from the dialysis fluid is the best parameter to calculate the peritoneal ultrafiltration efficacy and not the glucose concentration currently used.

CAPD prescription in current clinical practice

A total of 132 patients from 15 dialysis centers were studied. Analyses were made of each drained dialysate exchange over 24 hours to determine total peritoneal urea clearance (KpT, liters/day), and a 24-hour urine was collected to determine total renal urea clearance (KrT, liters/day) and the sum of KpT+KrT or KprT, liters/day. Body water volume (V, L) was estimated from gender and surface area, and daily fractional urea clearance (KprT/V) was calculated. Normalized protein catabolic rate (PCRN, grams/kilogram/day) was also calculated from the urea data. Major results were the following: KrT comprised 25% of KprT; the mean KprT/V was 0.28, but ranged from 0.10-0.50; an equivalent thrice-weekly hemodialysis KT/V was calculated from the KprT/V values and showed mean KT/V = 1.07, but 67% of values were less than 1.0. In contrast, the Health Care Finance Administration (HCFA) consensus criteria indicated 91% of prescriptions were adequate. These data indicate the need for clinical outcome studies with KprT/V randomized over the range 0.20-0.30 to better define the domain of adequate CAPD.

Dialysis-induced hypoxaemia

A crossover study to compare the effects of seven different dialysers on blood gas conditions during dialysis using acetate-containing dialysate was carried out at five centres in four countries. A significant decrease in pO2 was noted at both 15 and 60 min after the start of dialysis for all dialysers, with the greatest decrease at 60 min. Filtral caused the greatest reduction and F 60 the least change at both 15 and 60 min. These differences were statistically significant according to the ANOVA multiple-range test for variance. pCO2 also declined by 1.0-2.7 mmHg at 15 min and by 0.7-3.8 mmHg at 60 min. The delta pCO2 was comparable across dialysers and no significant differences were found. Although pH showed no change at 15 min, it was slightly but significantly increased at 60 min across all dialysers compared to predialysis values. There were no statistical differences between dialysers. Calculated blood bicarbonate content significantly decreased at 15 min and recovered at 60 min. Along with the greater decrease in pO2, a larger loss of total CO2 was noted for Filtral. On the other hand F 60 caused the least change in total CO2. This difference may be due to membrane characteristics affecting the diffusion coefficient for O2, CO2, and bicarbonate. Multifactorial mechanisms are likely to be involved, but reflex hypoventilation and an increase in O2 consumption also contributed to hypoxaemia in this study.

Increasing plasma phosphorus values by enriching with phosphorus the "acid concentrate" of a bicarbonate-buffered dialysate delivery system

Each of seven hypophosphatemic hemodialysis patients was dialyzed with a phosphorus-enriched, bicarbonate-buffered dialysate. The latter was prepared by the introduction of sodium phosphate salts to the "acid concentrate" of a bicarbonate-buffered dialysate delivery system. The patients tolerated the procedure well and their hypophosphatemia improved.

Stability of ciprofloxacin in peritoneal dialysis solution

The long-term stability of ciprofloxacin in dialysis fluid was studied. Ciprofloxacin was added to nine 2-L bags of dialysis solution containing 1.3% dextrose to yield a nominal concentration of 25 mg/L. Three bags each were stored at 4, 20, and 37 degrees C; three 20-mL samples were removed from each bag after 0, 0.5, 1, 2, 5, 7, 10, 14, 21, 28, and 42 days and analyzed in triplicate by high-performance liquid chromatography. Additional samples were removed from each bag on day 42 and analyzed by microbiological assay with Pseudomonas aeruginosa (nine samples tested for each storage temperature studied). The net percentage of change in ciprofloxacin concentration was 0.76% after storage at 4 degrees C, 1.02% after storage at 20 degrees C, and 0.75% after storage at 37 degrees C. Antimicrobial activity after storage at all three temperatures was confirmed by microbiological assay. Ciprofloxacin 25 mg/L was stable for 42 days when stored in dialysis fluid containing 1.36% dextrose at 4, 20, and 37 degrees C.

Variables associated with the assessment of systemic tumor necrosis factor alpha levels during hemodialysis

Conflicting results have been published concerning the systemic induction of the cytokine tumor necrosis factor alpha (TNF alpha) during hemodialysis (HD). We therefore evaluated in vitro TNF alpha production in whole blood as well as in vivo variability of TNF alpha levels in patients on long-term HD. Whole blood was incubated at room temperature (RT) with or without exogenously added endotoxin (ET), and plasma-TNF alpha was measured after 5, 30, 120, 240, and 960 min by specific enzyme immunoassay. Additionally, plasma-TNF alpha before and after 120 and 240 min HD was studied longitudinally once a week over a period of 4 weeks in 36 patients on Cuprophan (CU, n = 23) or polysulfone-F60 (PSu, n = 13) HD. Mean plasma TNF alpha levels in vitro rose from (mean) 8 pg/ml after 5 min to 12 pg/ml (120') and 32 pg/ml (960') even without ET addition, and to 18 pg/ml (after 120') and 88 pg/ml (after 960') when 0.1 microgram/ml ET were added. Pre-dialytic as well as intra-dialytic TNF alpha levels in patients showed high intra-individual variability. A substantial (> 100%) increase in plasma TNF alpha was observed during only 14 out of 84 treatments with CU and 20 out of 47 with PSu, however, the increase in TNF alpha was not statistically significant in either group. We conclude that the sampling procedure, if not carefully standardized, is a potential source of artifacts with regard to "systemic" TNF alpha levels. The high intra and inter-individual variability of plasma TNF alpha suggests that results of cross-sectional studies are questionable.

Behaviour of 12 trace elements in serum of uremic patients on hemodiafiltration

The concentrations of the trace elements As, Au, Cd, Cs, Cu, Fe, Hg, Mo, Rb, Se and Zn were studied in the serum of 5 patients with end-stage renal failure who were undergoing treatment with hemodiafiltration. The concentrations of the following elements differ significantly from the reference values: As, Cd, Cu, Hg and Mo are higher, while Rb, Se, Zn and some of the Cs values are lower. The observed concentration deviations may be due to the uremic state and/or the dialysis process. To asses the contribution of the latter, the elements were determined in the substitution fluid and in the dialysate before and after blood contact and passage through the artificial kidney. Our findings suggest that the concentration abnormalities could be related to the substitution fluid for Cs, Rb, Se and Zn and to the dialysate for Mo and Rb.

In vitro buffering capacity of residual peritoneal dialysate fluid: implications for peritoneal dialysis therapy

The buffering capacity of the residual peritoneal dialysate fluid from each of 5 patients undergoing continuous ambulatory peritoneal dialysis was assessed by titrating with fresh, conventional, acidic, and lactate-containing peritoneal dialysis solutions. It was found that residual fluids had considerable buffering capacity.

In vivo clearance and elimination of nine marker substances during hemofiltration with different membranes

The handling of low, middle and high molecular weight markers was examined in seven stable dialysis patients during hemofiltration with different membranes. Four membranes were examined in a randomized, crossover order (polysulfone, polyamide, AN69 polyacrylonitrile, Asahi polyacrylonitrile) by measuring plasma and dialysate concentrations of phosphate, creatinine, vitamin B12, beta 2-microglobulin, furanic acid, hippuric acid, retinol-binding protein, alpha-1-antitrypsin, and albumin. Sieving coefficients and plasma clearances of beta 2-microglobulin or retinol-binding protein were markedly or slightly lower during hemofiltration with the Asahi polyacrylonitrile membrane than with the other membranes (highest removal with polysulfone/AN69 polyacrylonitrile membranes). No differences of obvious clinical relevance could be seen between the four membranes. A high beta 2-microglobulin removal rate might be important to prevent dialysis-associated amyloidosis.

Peritoneal dialysis solution calcium concentration regulates peritoneal fibroblast proliferation in CAPD

Peritoneal fibrosis remains one of the major causes of dropout in continuous ambulatory peritoneal dialysis (CAPD), by reducing ultrafiltration capacity. Since studies in vitro have shown that cytoplasmic Ca2+ regulates the proliferation of most cell lines and the release of cytokines from immune cells, eight uremics and four controls at the start of CAPD were evaluated for the in vitro effects of different peritoneal dialysis solution (PDS) Ca2+ concentrations (1, 1.25, 1.75, and 2 mmol/L) on: 1) peritoneal fibroblast (PF) proliferation; 2) peritoneal macrophage (PM) and peritoneal lymphocyte (PL) release of interleukin-1 (IL-1) and interferon-gamma (IFN-gamma)--cytokines that are known to induce PF proliferation; and 3) cytoplasmic Ca2+ concentrations in PF, PM, and PL. Results showed that in both the uremics and controls, increasing the dose of Ca2+ in the medium induced a dose-dependent rise in PF proliferation, and in the release of IL-1 and IFN-gamma from PM and PL. Meanwhile, the cytoplasmic Ca2+ concentration of PF, PM, and PL also increased. With a PDS containing 1 mmol/L of Ca2+ in the uremics, these parameters were below normal; they exceeded the norm with a Ca2+ concentration of 1.75 and 2 mmol/L, and were normal with a Ca2+ concentration of 1.25 mmol/L. These data suggest that in CAPD patients, the use of a low Ca2+ PDS (1 and 1.25 mmol/L) may be useful in reducing the proliferation of PF and the production of IL-1 and IFN-gamma from PM and PL, thereby preventing peritoneal sclerosis.

Toxicity of heat sterilized peritoneal dialysis fluids is derived from degradation of glucose

Heat sterilization makes peritoneal dialysis (PD) solutions cytotoxic. Two compounds in the solutions, lactate and glucose, can be degraded by heat. This study's goal was to discover which of the compounds was responsible for the cytotoxicity. The influence of sterilization temperature on degradation of the compounds was also subjected to investigation. Solutions of glucose and lactate and a mixture of lactate and glucose were prepared. These were sterilized in glass ampules in an oil bath at different temperatures for varying times. Toxicity was determined as inhibition of cell growth with a fibroblast cell line (L929), and ultraviolet (UV) absorbance was measured at 284 nm. Lactate solutions did not show cytotoxicity after heat sterilization. Glucose solutions that were heat sterilized showed an increase in UV absorbance at 284 nm and were cytotoxic. The mixture of lactate and glucose exhibited the same cytotoxicity as glucose alone. Lower sterilization temperatures lead to increased cytotoxicity and an increase in UV absorbance at 284 nm. Results indicate that the toxic products formed during heat sterilization of PD fluids are derived from glucose.