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BackgroundIcodextrin induces ultrafiltration (UF) during long-dwell exchanges by creating a difference in oncotic pressure between the peritoneal cavity and plasma; however, the mechanisms governing intra-patient and inter-patient variability in UF when icodextrin is used remain largely unexplained. In the present study, we show theoretically that differences in peritoneal residual volume ( VR) have a more profound effect on UF with icodextrin use than with glucose use. This phenomenon is attributed to a differential effect of VRon oncotic, rather than osmotic, pressure between the peritoneal cavity and plasma.MethodsThe three-pore model was used to calculate the effect on UF of VRbetween 150 mL and 1200 mL when 7.5% icodextrin (ICO) or 3.86% glucose solution is used at the end of a 12-hour dwell in the four patient transport groups (that is, fast to slow). Oncotic (with ICO) and osmotic (with glucose) pressure differences averaged over the entire dwell were also calculated.ResultsAs expected, at a nominal VRof 300 mL, UF with glucose differed substantially between the four patient transport groups (2 – 804 mL), whereas UF with ICO did not (556 – 573 mL). When VRwas increased to 1200 mL from 150 mL, the concentrations of the oncotic and osmotic agents at the start of the dwell with an infusion volume of 2 L decreased to 4.9% from 7.0% with ICO and to 2.5% from 3.6% with glucose. The decrease in UF on average was greater with ICO [to 252 mL from 624 mL: that is, a reduction of 372 mL (60%)] than with glucose [to 292 mL from 398 mL: that is, a reduction of 106 mL (27%)]. Those trends agreed with the calculated reductions in the oncotic pressure difference with ICO [reduction of 12 mmHg (49%)] and the osmotic pressure difference with glucose [reduction of 19 mmHg (33%)].ConclusionsWhen ICO is used, VRmodifies the oncotic pressure difference between the peritoneal cavity and plasma to substantially alter UF. This modification suggests that potential causes of increased VRshould be considered when UF with ICO is considerably less than expected. Prospective clinical studies evaluating the relationship between VRand UF with ICO are warranted to validate the theoretical predictions in this report.

Background The high rate of cardiovascular mortality in patients with end-stage renal disease (ESRD) is a significant barrier to improved life expectancy. Unique in this population is the marked development and aggressive worsening of vascular calcification (VC). Pyrophosphate (PPi), an endogenous molecule, appears to naturally inhibit soft tissue calcification, but may be depressed in chronic kidney disease (CKD) and ESRD. Although once thought to be a promising therapeutic, PPi's very short half-life in circulation curtailed earlier studies. We tested the possibility that a slow, continuous entry of PPi into the circulation and prevention of VC might be achieved by daily peritoneal dialysis (PD). Methods Pharmacokinetic studies were first carried out in rats with renal impairment resulting from a 5/6 nephrectomy. Efficacy studies were then performed in the apolipoprotein E gene knockout mouse model overlaid with CKD. PPi was delivered by means of a permanent peritoneal catheter in a solution simulating PD, but without the timed removal of spent dialysate. von Kossa's staining followed by semiquantitative morphological image processing, with separation of inside (intimal) and outside (presumed medial) lesions, was used to determine aortic root calcification. Results In comparison to an intravenous bolus, delivery of PPi in a PD solution resulted in a slower, extended delivery over >4 h. Next, the efficacy studies showed that a 6-day/week PD-simulated administration of PPi resulted in a dose-dependent inhibition of aortic calcification in both intimal and medial lesions. A dose-response effect on total aortic calcification was also documented, with a full inhibition seen at the highest dose. A limited peritoneal catheter-related inflammation was observed, as expected, and included the placebo-treated control groups. This inflammatory response could have masked a lower level PPi-specific adverse effect, but none was observed. Conclusions Our findings suggest potential for PPi, administered during PD, to prevent the development of VC and to potentially extend the life of ESRD patients.

Peritoneal dialysis (PD) is a well-established form of therapy for stage 5 chronic kidney disease requiring renal replacement therapy. D-Glucose has been used successfully for several decades as the osmotic agent employed in dialysis solutions to achieve adequate fluid removal. The absorption of 100–200 grams of glucose per day has been suggested as potentially increasing cardiometabolic risk, particularly in patients with diabetes. Supporting and undermining evidence for this hypothesis is reviewed, with a focus on the role of glucose absorption in changes in body composition, dyslipidemia, and glycemic control in diabetic PD patients. Clinical strategies to optimize fluid removal while minimizing the metabolic impact of glucose absorption are also discussed.

Background: We evaluated the incidence of spontaneous peritonitis as well as the local inflammatory response and macroscopic changes in the peritoneum during the use of a bicarbonate/lactate-buffered (P) solution in comparison to conventional (D) solutions in rats on chronic peritoneal dialysis. Methods: Sixty-three male Wistar rats were implanted with peritoneal catheters. After 7 days, the animals were randomly divided into 2 experimental groups (32 rats in D, 31 rats in P) and infused twice daily over the following 4 weeks. Results: After 14 and 23 days, rats dialyzed with D had a higher peritonitis rate than those dialyzed with P. The median number of days until peritonitis occurred was 22 days for the rats in the D group and 29 days for the rats in the P group. Spontaneously infected rats dialyzed with the D solution had higher scores for adhesion formation. Conclusions: In this animal model, dialysis with P delayed the time to the 1st infection, reduced the overall peritonitis rate and reduced peritonitis-associated peritoneal adhesion formation during chronic peritoneal dialysis.

In the last 5 years, we have started to witness the emergence of new technologies and techniques that offer the potential for improved patient outcomes but which often still lack clinical demonstration and/or confirmation in well-designed, multicentre studies. These include biocompatible solutions, glucose sparing regimens, low-sodium solutions, bimodal solution formulations and continuous flow peritoneal dialysis (CFPD). This review discusses the potential benefits ascribable to each of these technologies and an analysis of the challenges that have to be surmounted before anyone of these candidate technologies can be declared as established. The demonstration of either hard clinical endpoints or validated surrogate endpoints is very feasible in terms of sample size requirements for some outcome measures, such as preservation of RRF, but will be much more challenging for other endpoints such as preservation of UF capacity.

Glucose has served well as the prototypical osmotic agent in peritoneal dialysis for more than 2 decades, because it affords many of the characteristics required of a safe and effective osmotic agent. The disadvantages of glucose include its rapid dissipation from the peritoneum and its resulting limited UF efficiency capacity in high and high-average transporters, the associated metabolic response to absorbed glucose in all patients, and the local effects of glucose, glucose degradation products, and hyperosmolality on peritoneal membrane structure and function. This paper briefly reviews the salient elements of glucotoxicity associated with conventional glucose-based peritoneal dialysis (PD) solution use, and then discusses emerging clinical benefits of newer nonglucose PD solutions. Potential future strategies designed to abrogate glucose-associated toxicity are then reviewed. These approaches include bimodal long-dwell solutions, nonglucose crystalloid osmotic agent mixtures, and administration of pharmacologically active agents.

BackgroundContrary to ultrafiltration, the three-pore model predictions of icodextrin absorption from the peritoneal cavity have not yet been reported likely, in part, due to difficulties in estimating the degradation of glucose-polymer chains by α–amylase activity in dialysate. We incorporated this degradation process in a modified three-pore model of peritoneal transport to predict ultrafiltration and icodextrin absorption simultaneously in rats and humans.MethodsSeparate three-pore models were constructed for humans and rats. The model for humans was adapted from PD Adequest 2.0 including a clearance term out of the peritoneal cavity to account for the absorption of large molecules to the peritoneal tissues, and considering patients who routinely used icodextrin by establishing steady-state plasma concentrations. The model for rats employed a standard three-pore model in which human kinetic parameters were scaled for a rat based on differences in body weight. Both models described the icodextrin molecular weight (MW) distribution as five distinct MW fractions. First order kinetics was applied using degradation rate constants obtained from previous in-vitro measurements using gel permeation chromatography. Ultrafiltration and absorption were predicted during a 4-hour exchange in rats, and 9 and 14-hour exchanges in humans with slow to fast transport characteristics with and without the effect of amylase activity.ResultsIn rats, the icodextrin MW profile shifted towards the low MW fractions due to complete disappearance of the MW fractions greater than 27.5 kDa. Including the effect of amylase activity (60 U/L) resulted in 21.1% increase in ultrafiltration (UF) (7.6 mL vs 6.0 mL) and 7.1% increase in icodextrin absorption (CHO) (62.5% with vs 58.1%). In humans, the shift in MW profile was less pronounced. The fast transport (H) patient absorbed more icodextrin than the slow transport (L) patient during both 14-hour (H: 47.9% vs L: 40.2%) and 9-hour (H: 37.4% vs L: 31.7%) exchanges. While the UF was higher during the longer exchange, it varied modestly among the patient types (14-hour range: 460 – 509 mL vs 9-hour range: 382 – 389 mL). When averaged over all patients, the increases in UF and CHO during the 14-hour exchange due to amylase activity (7 U/L) were 15% and 1.5%, respectively.ConclusionThe icodextrin absorption values predicted by the model agreed with those measured in rats and humans to accurately show the increased absorption in rats. Also, the model confirmed the previous suggestions by predicting an increase in UF specific to amylase activity in dialysate, likely due to the added osmolality by the small molecules generated as a result of the degradation process. As expected, this increase was more pronounced in rats than in humans because of higher dialysate concentrations of amylase in rats.

Glucose sparing is a central component of modern peritoneal dialysis therapy, necessary to reduce the trade-offs of the therapy in terms of membrane protection and alleviation of systemic consequences. We present a detailed exploration of a metric for this approach in the form of the index of ultrafiltration efficiency, that we propose as a guide for designing therapeutic regimens and for the development of new dialysis solutions. Based on insights from exploration of ultrafiltration efficiency with various dialysis solutions, we propose an approach to optimizing dialysis prescription.

The development of bacterial biofilms in the hydraulic circuit of hemodialysis machines is routinely prevented by frequent use of a variety of chemical and heat disinfection strategies. This study compared the effectiveness of several chemical disinfectants, commonly used either alone or in combination with a treatment regimen that involved cleaning plus heat disinfection using an in vitro Pseudomonas biofilm model. Effectiveness of these procedures was evaluated using total and viable biomass quantitation and polysaccharide and endotoxin determination. The chemical disinfection procedures were only partially successful in removing all biofilm components. Heat disinfection alone killed viable biofilm bacteria, but did not remove all the biomass components, including endotoxin. The combination of cleaning with citric acid followed by heat disinfection was the most effective in eliminating all biofilm components from the hydraulic circuit of the in vitro model.

The in vitro biocompatibility performance of a 25mmol/L bicarbonate/10mmol/L lactate-buffered peritoneal dialysis fluid. Background. The biocompatibility profile of a new peritoneal dialysis (PD) solution (Physioneal 35) was determined using a selection of in vitro assay systems. Physioneal 35 is buffered by a combination of 25mmol/L bicarbonate and 10mmol/L lactate, thereby providing a solution with a total of 35mmol/L of alkali to complement the currently available 25mmol/L bicarbonate and 15mmol/L lactate combination solution, Physioneal 40. In addition, the new solution contains a calcium concentration of 1.75mmol/L rather than 1.25mmol/L present in Physioneal 40. Physioneal 35 and 40 are manufactured in double chamber bag systems that permit separation of glucose from the buffer during sterilization. When the two chambers are mixed just before patient use, the resulting solution has a neutral pH and reduced glucose degradation content. Physioneal 35 was evaluated for its cytotoxicity potential using a murine fibroblast assay, its acute effect on human neutrophil and human peritoneal mesothelial cell function, and its in vitro potential to form advanced glycation end products (AGE). The biocompatibility characteristics of this new formulation were compared with that of a conventional, lactate-based solution and to that of its parent formulation, Physioneal 40. Methods Proliferation of murine fibroblasts was determined after exposure to dialysis fluids for 72hours. Cell viability was assayed by the ability to take up neutral red dye. Human neutrophils were exposed for 15 minutes to dialysis fluids, and their ATP content and phorbol 12-myristate 13-acetate (PMA) stimulated chemiluminescence response was determined as a measure of viability and respiratory burst activity, respectively. Cellular interleukin (IL)-1β–driven IL-8 synthesis by human mesothelial cells following acute exposure to dialysis fluids was also assessed. Advanced glycation end product formation in the dialysis fluids was measured after 5 and 20days of incubation with human serum albumin (HSA) as the model protein. Results In all assays employed, the biocompatibility profile of Physioneal 35 was similar to that of the Physioneal 40 parent formulation. Physioneal 35 showed a significant improvement in biocompatibility performance compared to a pH neutralized conventional lactate-buffered peritoneal dialysis solution in the murine fibroblast assay. In the acute exposure assays, human neutrophil viability and respiratory burst were significantly improved compared with the acidic, conventional solution; however, no statistically significant improvement were seen in mesothelial cells. AGE formation, which is thought to be an important mechanism by which glucose and glucose degradation products cause structural and functional changes of the peritoneal membrane, was significantly lower in Physioneal 35 compared with the conventional dialysis solution. Conclusion The biocompatibility profile of Physioneal 35 was similar to that of the original Physioneal 40 bicarbonate/ lactate-buffered dialysis solution, confirming that differences in both buffer content and calcium concentration do not affect biocompatibility performance. Both bicarbonate/lactate formulations (Physioneal 35 and Physioneal 40) were more biocompatible than a conventional lactate-buffered dialysis solution in this in vitro biocompatibility assessment.

A functional variant of the myeloperoxidase gene is associated with cardiovascular disease in end-stage renal disease patients. Cardiovascular disease (CVD) is the leading cause of mortality in end-stage renal disease (ESRD) patients and there is emerging evidence that genetic factors may contribute to the development of atherosclerosis. Myeloperoxidase (MPO) is an abundant enzyme involved in the production of free radicals. A functional G→A single nucleotide polymorphism (SNP) has been identified at position -463, where the A allele is associated with lower MPO expression. To analyze the association between this SNP and inflammation, oxidative stress, and CVD, we studied a cohort of 155 ESRD patients (52 ± 1 years, 62% males, 22% diabetics) shortly before the initiation of dialysis treatment. CVD was defined by medical history criteria; plasma interleukin-6 (IL-6) was used as a marker of inflammation, and plasma pentosidine as an estimation of oxidative protein damage. DNA from leukocytes was used for genotyping, performed by the pyrosequencing reaction. Only five patients (3%) had the genotype AA at the -463 position, whereas 38 (25%) had the GA and 112 (72%) had the GG genotype. No differences were noted in plasma IL-6 levels between the genotype groups, whereas the pentosidine levels were higher in the GG group (28.4 pmol/mg albumin [range, 8.5 to 123 pmol/mg albumin]) compared to the other two groups (21.4 pmol/mg albumin [range, 7.6 to 384 pmol/mg albumin; P < 0.05]). Patients with the GG genotype had a higher prevalence of positive serology for Chlamydia pneumoniae (51%) when compared to the carriers of the A allele (24%) (P < 0.05). The prevalence of CVD was lower in the AA (0%) and GA genotypes (18%), compared to the GG genotype (35%). The GG genotype was still associated with CVD after correction for age, diabetes, smoking, malnutrition, and inflammation. Our findings suggest that the -463 G→A SNP, which supposedly results in lower MPO activity, is associated with a lower prevalence of CVD in ESRD patients. It could be speculated that this effect is mediated by a decreased oxidative stress due to lower production of free radicals.

To identify the relative importance of peritoneal fibrosis and angiogenesis in peritoneal membrane dysfunction, adenoviral mediated gene transfer of angiostatin, a recognized angiogenesis inhibitor, and decorin, a transforming growth factor-beta-inhibiting proteoglycan, were used in a daily infusion model of peritoneal dialysis. A peritoneal catheter and subcutaneous port were inserted in rats. Five and fourteen d after insertion, adenovirus-expressing angiostatin, decorin, or AdDL70, a null control virus, were administered. Daily infusion of 4.25% Baxter Dianeal was initiated 7 d after catheter insertion and continued until day 35. Three initial doses of lipopolysaccharide were administered on days 8, 10, and 12 to promote an inflammatory response. Net ultrafiltration was used as a measure of membrane function, and peritoneum-associated vasculature and mesenteric collagen content was quantified. Ultrafiltration dysfunction, angiogenesis, and fibrosis were observed in daily infusion control animals. Animals treated with AdAngiostatin demonstrated an improvement in net ultrafiltration (-3.1 versus -7.8 ml for control animals; P = 0.0004) with a significant reduction in vessel density. AdDecorin-treated animals showed a reduction in mesenteric collagen content (1.8 versus 2.9 microg/mg; P = 0.04); however, AdDecorin treatment had no effect on net ultrafiltration. In a rodent model of peritoneal membrane failure, net ultrafiltration was significantly improved and peritoneal-associated blood vessels were significantly reduced by using adenovirus-mediated gene transfer of angiostatin. Decorin, a transforming growth factor-beta-inhibiting proteoglycan, reduced collagen content but did not affect net ultrafiltration. Improvement in the function of the peritoneum as a dialysis membrane after treatment with angiostatin has implications for treatment of peritoneal membrane dysfunction seen in patients on long-term dialysis.

♦ Objective Conventional lactate-buffered peritoneal dialysis (PD) solutions have several bioincompatible characteristics, including acidic pH, lactate buffer, and the presence of glucose degradation products (GDPs). These characteristics, along with inflammation, are believed to contribute to membrane dysfunction in peritoneal dialysis patients. A new PD solution containing a bicarbonate/ lactate buffer system with physiologic pH and low GDPs has shown improved biocompatibility in both in vitro and ex vivo studies. In the present study, the concentrations of cytokines interleukin-6 (IL-6), tumor necrosis factor alpha (TNFα), and vascular endothelial growth factor (VEGF), were measured in timed overnight effluents from PD patients continuously dialyzed with either lactate-based control solution (C) or bicarbonate/lactate–based solution (B/L) for 6 months. ♦ Methods Effluents from 92 continuous ambulatory peritoneal dialysis (CAPD) patients were collected when the patients were entered into the study (baseline, all patients on C for more than 3 months), and at 3 and 6 months following randomization to C ( n = 31) or to B/L ( n = 61). Effluent samples were filtered, stored frozen, and then assayed for IL-6, TNFα, and VEGF by ELISA. ♦ Results A significant decrease in effluent IL-6 was seen at 3 months and at 6 months in the B/L-treated patients. Levels of VEGF were significantly reduced at 3 months. No changes in the levels of IL-6 or VEGF were seen in the C-treated patients, and no changes in TNFα were seen in either group over time. ♦ Conclusions Treatment with B/L is associated with decreased IL-6 synthesis and decreased VEGF secretion. The data suggest that the use of B/L solution is associated with reduced intraperitoneal inflammation and potential for angiogenesis. The use of B/L solution may, over time, help to restore peritoneal homeostasis and therefore preserve the function of the membrane in peritoneal dialysis.

The objective of this study was to compare, using in vitro quantitative microbiology, the ability of two commercially available peritoneal dialysis solution delivery systems to prevent and remove, via convective fluid flow, intralumenal fluid path bacterial contamination. The two systems (A and B) differed in both the configuration of their flow control, or Y-junction and the method of fluid flow control and also in the design of their Luer tubing connectors. System A had a tubing type Y-junction that requires clamps to control fluid flow and uses a connector with a male Luer that is deeply recessed within a shroud. System B has a dial-type rigid Y-junction with in-line flow control and a connector with a male Luer that is shrouded but not recessed. System A connectors allowed significantly (p < 0.0001) fewer bacteria to be transferred into the fluid path than System B after simulated touch contamination. Also, when an equivalent number of bacteria were deliberately placed into the fluid paths of both systems, System A was more effective in removal of the bacterial contamination by convective fluid flow than System B (p < 0.0001), resulting in fewer organisms infused into the simulated peritoneum. Specific design features of System A, such as a recessed male Luer, and a Y-junction fluid flow path with low turbulence were likely explanations for its superior results. This study emphasizes the importance of connector and fluid path flow design in the aseptic performance of peritoneal dialysis delivery systems.

Pre-clinical biocompatibility testing of peritoneal dialysis (PD) solutions has become an integral part of new solution development. The construction of a pre-clinical screening program for solution biocompatibility should take a hierarchical approach, starting with in vitro cell viability and function assays. The selection of cell types and assay systems for the in vitro studies should be broad enough to permit a balanced interpretation. Whenever possible, animal models are recommended for the next hierarchical level of testing, followed by human ex vivo study designs. Designs of the latter sort provide evidence that a new solution formulation is exerting an altered biological response in vivo; the response is not purely an in vitro artifact or restricted to a given animal species. This article discusses the various approaches available for biocompatibility testing during the pre-clinical phase of solution development, with an emphasis on the advantages and drawbacks of each method.

Department of Medicine,1 Hennepin County Medical Center, University of Minnesota Medical School, Minneapolis, Minnesota; Albany College of Pharmacy,2 Albany, New York, U.S.A.; Department of Peritoneal Dialysis,3 Academic Medical Center, Amsterdam, The Netherlands; Manchester Royal Infirmary,4 Manchester, United Kingdom; Vanderbilt University Medical Center,5 Nashville, Tennessee; Baxter Healthcare Corporation,6 McGaw Park, Illinois, U.S.A.; Renal Division,7 Jikei-kai University, School of Medicine, Tokyo, Japan; University of Pittsburgh Medical Center,8 Pittsburgh, Pennsylvania, U.S.A.; Renal Division,9 Department of Medicine, Evangelic School of Medicine, Curitiba Parana, Brazil; University of Toronto,10 Toronto Hospital, Toronto, Ontario, Canada

Glucose has been used successfully for more than two decades in peritoneal dialysis, and in this regard, must be considered a safe and effective osmotic agent. Recently, however, insight has been growing about the potential for metabolic and peritoneal effects arising from long-term exposure to high glucose concentrations—for example, hyperlipidemia and loss of peritoneal ultrafiltration. Clinical concerns over exposure to excessive glucose and glucose degradation products (GDPs) during peritoneal dialysis can be significantly ameliorated by the use of non-glucose-based peritoneal dialysis (PD) solutions, in combination with more biocompatible glucose-based formulations. Peritoneal exposure to GDPs can be reduced by using low-GDP-containing glucose formulations and non glucose solutions such as amino acids and icodextrin. Peritoneal glucose exposure, hyperosmolar stress, and carbohydrate absorption can be reduced by using a combination of icodextrin and amino acids.

The impact on peritoneal macrophage (PMO) function of acidic lactate-buffered (Lac-PDF [PD4]; 40 mmol/L of lactate; pH 5.2) and neutral-pH, bicarbonate-buffered (TB; 38 mmol/L of bicarbonate; pH 7. 3) and bicarbonate/lactate-buffered (TBL; 25 mmol/L of bicarbonate/15 mmol/L of lactate; pH 7.3) peritoneal dialysis fluids (PDFs) was compared during a study of continuous therapy with PD4, TB, or TBL. During a run-in phase of 6 weeks when all patients (n = 15) were treated with their regular dialysis regimen with Lac-PDF, median PMO tumor necrosis factor alpha (TNFalpha) release values were 203.6, 89.9, and 115.5 pg TNFalpha/10(6) PMO in the patients subsequently randomized to the PD4, TB, and TBL treatment groups, respectively. Median stimulated TNFalpha values (serum-treated zymosan [STZ], 10 microgram/mL) were 1,894.6, 567.3, and 554.5 pg TNFalpha/10(6) PMO in the same groups, respectively. During the trial phase of 12 weeks, when the three groups of patients (n = 5 per group) were randomized to continuous treatment with PD4, TB, or TBL, median constitutive TNFalpha release values were 204.7, 131.4, and 155.4 pg TNFalpha/10(6) PMO, respectively. Stimulated TNFalpha values (STZ, 10 microgram/mL) were 1,911, 1,832, and 1,378 pg TNFalpha/10(6) PMO in the same groups, respectively. Repeated-measures analysis of variance comparing the run-in phase with the trial phase showed that PMO TNFalpha release was significantly elevated in patients treated with both TB (P = 0.040) and TBL (P = 0.014) but not in patients treated with Lac-PDF (P = 0. 795). These data suggest that patients continuously exposed to bicarbonate- and bicarbonate/lactate-buffered PDFs might have better preserved PMO function and thus improved host defense status.

ObjectiveTo compare the effect of Dianeal and two newly-formulated bicarbonate-based peritoneal solutions on intracellular pH (pHi), tumor necrosis factor-α (TNFα) mRNA level, and TNFα secretion by peritoneal macrophages (PMΦ).Design and MeasurementsPeritoneal macrophages were isolated from dialysates collected after overnight dwells in peritonitis -free continuous ambulatory peritoneal dialysis patients. Dialysis solutions contained 1.5% or 4.25% dextrose. HCO3 concentrations of bicarbonate(TB)and bicarbonate/lactate-buffered (TBL) solution were 38 mM and 25 mM, respectively. TBL also contained lactate at a concentration of 15 mM. pCO2 levels were 78 mmHg and 51 mmHg, respectively. In all experiments pC02 was carefully maintained at a stable level. The pHi was measured by spectrofluorometry in BCECF-Ioaded PMΦ exposed to different dialysis solutions or Hank's balanced salt solution. TNFα levels were measured by ELISA in the supernatant of lipopolysaccharide (LPS) stimulated PMΦ after their incubation in different solutions for 15 and 30 minutes. TNFα mRNA was measured by reverse transcriptase polymerase chain reaction (RT PCR) of total RNA extracted from LPS-stimulated PMΦ after their incubation in different solutions for 30 minutes. β-actin mRNA was used as the control.ResultsDianeal caused a profound drop in pHi to below 6.2. Following an initial drop, pHi stabilized after 4 minutes at levels of 6.96 and 6.8 after incubation in TB and TBL, respectively. In comparison to the control solution, a fall of 11% and 21% in TNFα secretion was seen after incubation in TB for 15 and 30 minutes, respectively, and 15% and 26% after incubation in TBL. Under identical conditions, Dianeal (Baxter, McGaw Park, IL, U.S.A.) caused 59% and >95% suppression of TNFα secretion. Accordingly, TNFα mRNA level in PMΦ was severely depressed by Dianeal but no detectable inhibition was observed following incubation for 30 minutes in TB and TBL. When dextrose concentration in TB and TBL was increased from 1.5% to 4.25%, TNFα secretion by PMΦ was not suppressed by more than 49%, even after 30 minutes incubation. Moreover, suppression of TNFα mRNA levels could not be detected with TB or TBL even at high dextrose concentrations.ConclusionsIn contrast to Dianeal, both bicarbonate based solutions caused only a mild drop in pHi of PMΦ. We postulate this effect to be responsible for the improved capacity of PMΦ to secrete TNFα when incubated in bicarbonate-based solutions compared to Dianeal. Reflecting its known cytotoxicity, dextrose in high concentrations diminishes the protective effect of TB and TBL on immune function of PMΦ. TBL is as effective as TB in preventing the deleterious effect of Dianeal on PMΦ function.

ObjectivesThe aims of the current study were: (1) to determine the effects of peritoneal dialysis (PD) solutions at different glucose concentrations on the growth of cultured cells; (2) to determine whether a bicarbonate/ lactate-based solution, as a result of the configuration of its components during heat sterilization in a two-chambered bag, was lower in glucose degradation products than a corresponding lactate-based PD solution; and (3) to determine whether lower glucose degradation corresponded to a decreased inhibition of cell growth.DesignGrowth inhibition of cells exposed to lactatebased PD solutions at three different glucose concentrations was determined. Bicarbonate/lactate-based and lactate-based solutions at high glucose concentration (3.86%) were further analyzed for presence of glucose degradation products and inhibition of cell growth.MethodsCell growth was determined by neutral red uptake, measured by optical density at 540 nm. Glucose degradation to acetaldehyde or fructose was determined by gas chromatographymass spectroscopy and highperformance liquid chromatography.ResultsOnly 3.86% glucose lactate-based PD solution caused significant inhibition of cell growth (p < 0.05). The heat-sterilized, bicarbonate/lactate-based solution (3.86% glucose) had lower levels of fructose and acetaldehyde than a conventional heat-sterilized, lactatebased solution with the same glucose concentration. Growth of cultured cells exposed to the bicarbonate/ lactate-based solution was significantly improved (p < 0.05) over growth in the conventional solution.ConclusionsThe bicarbonate/lactate-based solutions, manufactured and heat-sterilized in two-chambered bags, were lower in glucose degradation products than the corresponding lactate-based PD solutions, and demonstrated improvedin vitrobiocompatibility as measured by the growth of cultured cells.

Objective Cellular immune function in peritoneal dialysis patients has been shown to be depressed, but the mechanism of this immunosuppression has not been ascertained. Because calcium is an important mediator of lymphocyte activation, this study was designed to investigate if there was an alteration of calcium metabolism in the lymphocytes of continuous ambulatory peritoneal dialysis (CAPD) patients. Design Sixteen CAPD patients were studied at the initiation of CAPD and after two months of treatment. Twenty-three normal controls were also enrolled in the study. Cytoplasmic calcium changes were investigated in response to the mitogen phytohemagglutinin (PHA) in peripheral blood and peritoneal lymphocytes, using the intracellular calcium probe indo-1 and flow cytometry. Baseline cytoplasmic calcium levels and changes in cytoplasmic calcium in response to PHA were assessed at the initiation of CAPD and after two months of therapy. Results Peripheral lymphocytes of patients and controls had similar calcium baseline levels, but the peritoneal lymphocytes had baseline cytoplasmic calcium levels averaging 81% higher than the corresponding calcium levels of the patients’ peripheral blood lymphocytes. As compared to peripheral lymphocytes, the response to PHA stimulation was significantly less in the peritoneal lymphocytes, increasing an average of only 46.8% above baseline. Peripheral blood lymphocytes of the patients responded by an average increase of 78.9% over baseline. Control cells increased an average of 66.3% over baseline. Follow-up studies done two months after the initiation of CAPD indicated there were no significant changes (as compared to month 0) that occurred in baseline or stimulated intracellular calcium concentrations. Conclusions While the peripheral lymphocytes of CAPD patients respond adequately to PHA, the high baseline calcium levels of the peritoneal lymphocytes suggest that these cells may be in a state of chronic activation and may respond minimally to an antigenic challenge.

♦BackgroundPeritoneal dialysis (PD) solutions containing icodextrin as the osmotic agent have advantages during long dwells. The glucose polymers that constitute icodextrin are a heterogeneous mix of molecules with a polydispersity [ratio of weight-average to number-average molecular weight (Mw/Mn)] of approximately 2.6. The present study evaluates whether modifications in the polydispersity and concentration of glucose polymers can improve ultrafiltration (UF) without an associated increase in carbohydrate absorption (CA).♦MethodsComputer simulations using a three-pore model of peritoneal transport during a long dwell in PD patients predict that, in general, compared with 7.5% icodextrin, glucose polymers with a Mw greater than or equal to 7.5 kDa, a polydispersity less than 2.6, and concentrations greater than 7% could achieve higher UF without higher CA. Based on the simulations, we hypothesized that, compared with 7.5% icodextrin, glucose polymers with a Mw of 18 – 19 kDa and a polydispersity of 2.0 at 11% concentration could achieve higher UF without a higher CA. We tested this hypothesis in experimental studies using 8-hour dwells in New Zealand White rabbits. In those studies, UF was measured by complete fluid collection, and CA was measured by subtracting the total carbohydrate in the collected fluid from the carbohydrate initially infused.♦ResultsThe UF was higher with 11% 19 kDa glucose polymer than with 7.5% icodextrin (mean ± standard deviation: 89 ± 31 mL vs 49 ± 15 mL; p = 0.004) without higher CA (5.2 ± 0.9 g vs 5.0 ± 0.9 g, p = 0.7). Similar results were seen with the 11% 18 kDa glucose polymer, which, compared with 7.5% icodextrin, resulted in higher UF (mean ± standard deviation: 96 ± 18 mL vs 66 ± 17 mL; p < 0.001) without higher CA (4.8 ± 0.7 g vs 5.2 ± 0.6 g, p = 0.2).♦ConclusionsThe findings demonstrate that, compared with 7.5% icodextrin solution, long-dwell PD solutions containing 11% glucose polymers with a Mw of 18–19 kDa and a polydispersity of 2.0 can provide higher UF without higher CA.

The recommendations provided in this document represent a distillation of various experiences, as well as data obtained from published studies in the setting of substantial changes in antibiotic sensitivity. It is hoped that this revised compilation will provide a basis upon which future developments and advances can be made in the therapeutic approach to infectious complications of peritoneal dialysis.

The inclusion of bicarbonate in the formulation of peritoneal dialysis solutions may avoid the in vitro impairment of certain cell functions seen with acidic lactate-based fluids. The supranormal physiological levels of HCO3- and PCO2 inherent in such formulations may, however, not be biocompatible. This study compared the in vitro biocompatibility of a pH 5.2 lactate-based formulation with formulations containing either 40 mM lactate at pH 7.4, 38 mM HCO3- at pH 6.8 (PCO2 at approximately 240 mm Hg) or 7.4 (PCO2 at approximately 60 mm Hg), and 25 mM HCO3- plus 15 mM lactate at pH 6.8 (PCO2 at approximately 160 mm Hg) or 7.4 (PCO2 at approximately 40 mm Hg). Significant release of lactate dehydrogenase or decreases in ATP content by human peritoneal mesothelial cells (HPMC) and human peripheral polymorphonuclear leukocytes (PMN) after a 30-min exposure to each test solution was only seen with the pH 5.2 lactate-based fluid. The ATP content of HPMC exposed to this fluid returned to control levels after 30 min of recovery in M199 control medium but showed a trend toward decreasing ATP content at 240 min. Similarly, interleukin (IL)-1 beta-induced IL-6 synthesis by HPMC was also only significantly reduced by the pH 5.2 lactate solution. PMN chemiluminescence was unaffected by 30-min exposure to all test solutions except for the pH 5.2 lactate formulation. Staphylococcus epidermidis phagocytosis was reduced to between 46 to 57% of control with all test solutions except the pH 5.2 lactate solution, which further suppressed the chemiluminescence response to 17% of control. These data suggest that short exposure to supranormal physiological levels of HCO3- and PCO2 does not impair HPMC or PMN viability and function. Furthermore, neutral pH lactate-containing solutions show equivalent biocompatibility to bicarbonate-based ones.

Patients with end-stage kidney disease exhibit the retention of a large variety of solutes that may affect a range of biological functions and, for instance, contribute to elevation of cardiovascular risk and modulate inflammatory responses. Such uraemic retention solutes can be classified on the basis of molecular size and protein binding as reviewed recently by the European Uraemic Toxin Work Group (EUTOX) [1]. Serum levels of uraemic retention solutes will reflect a complex interplay of changes in production or generation, reduced renal clearance and adsorption or clearance during renal replacement therapy, but could also be affected by protein binding or non-renal (e.g. hepatic) clearance. The recent EUTOX review demonstrated that new studies using state-of-the-art methodology show major differences in the concentration of some retention solutes from original reports. As nephrologists consider how to adjust dialysis therapy regimes to improve clinical outcomes, it is important to carefully consider the biological significance of elevated levels of any solute and how it may be influenced by the mode or dose (or intensity) of dialysis. For many years, attention has focused on highmolecular-weight toxins or middle molecules and their effects in dialysis patients or changes with dialysis therapy. β2-Microglobulin (β2M) is commonly measured as a representative middle molecule because its concentration is elevated significantly in end-stage kidney disease patients, it can be readily measured in serum, and it is readily cleared by high-flux membranes. Large randomized clinical trials have used either the clearance of β2M or serum β2M concentrations to define high-flux haemodialysis [2, 3] or haemodiafiltration [4]; however, these trials have failed to demonstrate that the use of high-flux membranes generally enhance patient survival in haemodialysis or haemodiafiltration therapies, although there may be benefits in certain patient subgroups [3–5]. These results were disappointing; many nephrologists expected more clear evidence of the importance of middle molecule removal in determining patient outcomes. The reasons why these large clinical trials did not more clearly demonstrate improved patient survival remain incompletely understood. One possible reason is that the trial interventions did not provide clearances of middle molecules that were large enough to improve patient survival. Mean predialysis serum β2M concentrations during the follow-up phase were 33.5 mg/L in the high-flux group during the HEMO study [6] and 26.4 mg/L in the haemodiafiltration group during the CONTRAST study [4], but these concentrations are still more than 10-fold higher than in individuals with normal kidney function. Furthermore, although the absolute levels of serum β2M were not reported in the primary outcome paper from the MPO study, serum levels of β2M for patients treated with high-flux membranes increased during the follow-up because incident patients participated in that study [3] and residual kidney function presumably dropped over time. In that study, the increase in serum β2M concentration in patients treated by highflux membranes was less than that in those treated by low-flux membranes; nevertheless, serum levels of β2M, and likely of other middle molecules, continued to increase above normal levels during the follow-up in patients treated by high-flux membranes. Although improvements to high-flux membrane performance continue

Background Icodextrin, a glucose polymer with a polydispersity [ratio of weight-average molecular weight (Mw) to number-average molecular weight] of approximately 2.6, has been shown, compared with glucose, to provide superior ultrafiltration (UF) efficiency [ratio of UF to carbohydrate (CHO) absorbed] when used as an osmotic agent during a long-dwell peritoneal dialysis exchange. In an experimental rabbit model, we evaluated the effect of Mw on the UF and UF efficiency of glucose polymers with low polydispersity. Methods A crossover trial in female New Zealand White rabbits (2.20 – 2.65 kg) with surgically implanted peritoneal catheters evaluated two glucose polymers at nominal concentrations of 7.5 g/dL: a 6K polymer (Mw: 6.4 kDa; polydispersity: 2.3) and a 19K polymer (Mw: 18.8 kDa; polydispersity: 2.0). Rabbits were randomized to receive either the 6K ( n = 11) or the 19K ( n = 12) solution during the first exchange (40 mL/kg body weight). The alternative solution was evaluated in a second exchange 3 days later. During each 4-hour dwell, the UF and total glucose polymer CHO absorbed were determined. Results The UF was higher for the 6K ( p < 0.0001) than for the 19K polymer (mean ± standard deviation: 73.6 ± 30.8 mL vs. 43.0 ± 20.2 mL), as was the amount of CHO absorbed (42.5% ± 9.8% vs. 35.7% ± 11.0%, p = 0.021). In spite of higher CHO absorption, an approximately 50% higher ( p = 0.029) UF efficiency was achieved with the 6K polymer (28.3 ± 18.8 mL/g) than with the 19K polymer (19.0 ± 11.3 mL/g). The results were independent of the order of the experimental exchanges. Conclusions Glucose polymers with low polydispersity are effective osmotic agents in a rabbit model. The low-Mw polymer was more effective at generating UF and had a higher UF efficiency, but those results came at the expense of the polymer being more readily absorbed from the peritoneal cavity.

The contribution of glucose or glucose degradation products (GDPs) to AGE formation associated with peritoneal dialysis (PD) fluids was determined by incubating lysozyme with PD fluids or glucose or GDPs with or without replenishment of the incubation solutions. Replacement of PD fluid or GDPs enhanced AGE fluorescence generation compared to continuous incubation. The converse occurred with glucose incubations, suggesting that GDPs in sterilised PD fluids are largely responsible for AGE formation.

Reprocessing of used dialyzers with chemical disinfectants is practiced commonly in the United States and in some areas of Western Europe. Concern over residual toxic or allergenic agents has encourag

A survey of the literature suggests continued interest in modifying the composition of peritoneal dialysis solutions. Osmotic agents such as glucose polymers and short-chain polypeptides may find a role in peritoneal dialysis fluids as partial substitutes for dextrose. New solutions containing amino acids should serve as more than sinks for uremic toxins by providing nutritional support and by ameliorating uremic lipid abnormalities. Increasing emphasis is being paid to biocompatibility during the development of new peritoneal dialysis fluids.

The role of peritoneal lymphocytes in host immunity for continuous ambulatory peritoneal dialysis (CAPD) patients Is just beginning to be understood. CAPD therapy Increases the proportion of peritoneal lymphocytes, most of which demonstrate signs of activation. There are decreased peritoneal T cells and increased peritoneal B cells as compared to the patients’ peripheral blood. When studies examine Immunophenotypes of peripheral and peritoneallymphocytes over time, no significant changes are found. Although changes in peritoneal lymphocyte subsets occur during peritonitis episodes, there are no changes In peripheral blood lymphocytes. The purpose of this article Is to provide a brief review of research that has studied lymphocytes In CAPD patients.

Mercury vapor sourced ultraviolet light has been used for several years to disinfect connections that are integral to peritoneal dialysis solution delivery systems. This in vitro study evaluated the suitability of xenon flash sourced ultraviolet light as an effective alternative disinfecting agent. Candida albicans was determined to be at least four times more resistant than Staphylococcus epidermidis, Staphylococcus aureus, Streptococcus mitis, and Pseudomonas aeruginosa to ultraviolet radiation generated by both mercury vapor and xenon flash devices. Both ultraviolet devices effectively disinfected transfer set spikes that were inoculated intraluminally with each of these five test microorganisms suspended in a pool of patient dialysis effluent. However, ultraviolet (254 nm) absorbance values of dialysis effluent was found to vary greatly between patients, with the most ultraviolet-opaque effluent significantly reducing the microbicidal effectiveness of the mercury vapor, but not the xenon flash system.

This article provides a review of studies on peritoneal white blood cells (WBC) in CAPD patients. To some extent these studies support the concept that the peritoneal cavity of these patients contains adequate-functioning WBC that can provide effective antimicrobial defenses when they are studied in dialysate-free media. Commercially available dialysis solutions significantly impair WBC function. In some patients with high incidences of peritonitis, there appears to be reduced bactericidal capacity of their peritoneal macrophages. CAPD seems to contribute to a state of both macrophage and lymphocyte activation in the peritoneal cavity. The clinical consequences of this chronic activation are not known.

The ultrafiltration (UF) efficiency of peritoneal dialysis (PD) solutions, defined as the net UF divided by the amount of carbohydrate absorbed per dwell, has been shown to be higher during long dwells with 7.5% icodextrin solution (Extraneal: Baxter Healthcare Corporation, Deerfield, IL, U.S.A.) than during those with glucose-based solution (2.5% and 4.25% Dianeal: Baxter Healthcare Corporation), prompting a better understanding of UF efficiency. We used the three-pore kinetic model of PD transport to investigate UF efficiency for single long dwells and various combinations of multiple short glucose-based dwells during automated PD (APD). To demonstrate a practical consequence of the effect of dwell time, we simulated two hypothetical APD prescriptions (A and B) in which fluid with a high glucose concentration was used during either the long day dwell (A: 4.25%; B: 2.5%) or the short night dwells (A: 3 x 1.5% + 1 x 2.5%; B: 4 x 2.5%). Computer simulations showed that higher glucose concentrations and shorter dwell times increase the UF efficiency of a single dwell, and UF efficiency depends on patient transport status. When 24-hour APD therapy was simulated for a low-average transporter, the net UF did not differ considerably (A: 1132 mL; B: 1154 mL), but total carbohydrate absorption was higher when solution with a high glucose concentration was used during the single long dwell (A: 146 g; B: 137 g), resulting in lower UF efficiency (A: 7.8 mL/g; B: 8.4 mL/g). We conclude that the UF efficiency of the entire regimen should be considered in prescribing PD therapy. When available, Extraneal provides the best UF efficiency during long dwells. Our simulations suggest that raising the glucose concentration in the short dwells and lowering it in the long dwell is the optimal strategy to maximize UF efficiency during APD when Extraneal is not available.

The purpose of this study was to determine if there were differences in selected dialysate white blood cells (WBC) parameters between continuous ambulatory peritoneal dialysis (CAPD) patient groups identified as having a high or low incidence of peritonitis. Parameters studied were total peritoneal WBC yield, percentage and absolute number of various WBC types, and expression of WBC receptors known to be involved in normal host defense mechanisms. WBCs were obtained from peritoneal dialysis effluents (overnight dwell), which were collected at monthly intervals for 6 to 8 months from eight CAPD patients-four with a history of high peritonitis incidence (HPI) (more than two episodes in 12 months) and four with a history of low peritonitis incidence (LPI) (no episodes in more than 24 months). Our results demonstrated that there was no significant difference in the overall mean total cell yields or absolute cell counts between the two patient groups. WBC differentials, although differing somewhat among patients, stayed quite stable over time for an individual patient and there was no significant difference between the two patient groups. Analysis of receptors on the peritoneal WBC was performed using flow cytometry and fluorescein-conjugated chemotactic factors (C5a and Met-Leu-Phe-Lys), as well as monoclonal antibodies specific for Fc receptors and complement receptors, CR1(CD35) and CR3 (CD11 b). Although there was a trend toward increased expression of all of these receptors in the HPI patients, there was no significant difference in the fluorescence intensity of peritoneal neutrophils or macrophages that expressed these receptors between the two patient groups. It has been proposed that altered peritoneal host defense mechanisms exist in patients with a high rate of peritonitis. However, based on the parameters analyzed in this study, no significant differences could be found among patients or between groups identified as having a high or low incidence of peritonitis.

Patients on continuous ambulatory peritoneal dialysis (CAPD) who reside long distances from a CAPD center often use community medical laboratories to document and manage episodes of peritonitis. We examined the feasibility of using large volume cultures as an alternative to more costly and labor intensive methods and to enhance earlier recovery of microorganisms from these patients. Three methods of processing dialysate from patients on CAPD were compared: (a) inoculation of 400 mL dialysate into a transfer bag (Baxter Healthcare, Inc., Round Lake, IL) containing 100 mL of 5-fold concentrate of trypticase-soy broth: (b) inoculation of 5 mL into each of two Bactec bottles (Johnston Laboratories, Towson, MD): and (c) centrifugation of 50 mL and culture of the sediment without white cell lysis on plated media and two Bactec bottles. Of the 58 specimens cultured, 34 (59%) were positive by one or more methods. Antimicrobial activity was detected in 20158 (34%) dialysates, which represent 54% of all no-growth cultures. Of the 34 culture-positive specimens, microorganisms were recovered on plated media in 22 (65%); by the centrifugation system in 32 (94%); by the routine Bactec system in 28 (82%); and by large volume culture in 30 (88%). The large volume culture system is an acceptable alternative to the more costly Bactec System and the labor intensive centrifugation method but does not significantly improve recovery of microorganisms.

Background: Wasting and inflammation are two common risk factors for death in patients with end-stage renal disease (ESRD). Interleukin-1β (IL-1β) and its receptor antagonist (IL-1Ra) may play a pivotal role in the pathogenesis of wasting and inflammation. Methods: To investigate effects of the IL-1 gene cluster polymorphisms on wasting and inflammation, we studied 189 ESRD patients (52 ± 12 years, 62% males) close to the start of renal replacement therapy. 205 healthy volunteers served as controls. We analyzed the IL-1B –511C/T, –31C/T, and +3954C/T polymorphisms as well as a variable number of a tandem repeat (VNTR) in IL-1RN. Nutritional parameters included serum albumin level, subjective global nutritional assessment (SGA), and body composition evaluated by dual-energy X-ray absorptiometry (DXA). We used serum high-sensitivity C-reactive protein (hsCRP) as a marker of inflammation. Results: Wasting (SGA >1) was present in 31%, whereas inflammation (CRP ≧10 mg/l) was present in 36% of the patients. The male carriers of the –511T/T and –31C/C genotypes had a lower prevalence of wasting (p < 0.05), higher body mass index (BMI) (p < 0.05), and higher lean body mass (LBM) (p < 0.01). In a stepwise multiple regression model, age (p < 0.05), BMI (p < 0.01) and the IL-1B –511 genotype (p < 0.01) were independently associated with LBM. The carriers of the +3954T allele had a lower prevalence of inflammation (p < 0.05) and lower serum hsCRP (p < 0.05). The VNTR in IL-1RN was not associated with any markers. Conclusion: The investigated IL-1 gene cluster polymorphisms were associated with nutritional status and inflammation in ESRD patients, but marked differences were found between the genders. These polymorphisms could have prognostic utility for predicting wasting and inflammation in ESRD patients.

Low fetuin-A levels are associated with cardiovascular death: Impact of variations in the gene encoding fetuin.BackgroundVascular calcification is common among end-stage renal disease (ESRD) patients and a central characteristic of the atherosclerotic cardiovascular disease observed in dialysis patients. Fetuin-A, a circulating calcium-regulatory glycoprotein that inhibits vascular calcification, is associated with inflammation and outcome in dialysis patients. In the present study, we evaluated the association between fetuin-A, clinical phenotype, and outcome, as well as the impact of fetuin gene (AHSG) polymorphisms on the protein product and outcome.MethodsIn a cohort of 258 (161 males) ESRD patients starting renal replacement therapy [glomerular filtration rate (GFR) 6.8 ± 0.2 mL/min] aged 52 ± 1 years the following parameters were studied: presence of malnutrition (subjective global assessment), comorbidity [diabetes mellitus and clinical manifest cardiovascular disease (CVD)], carotid plaques (N = 101), hs-CRP, fetuin-A, S-albumin, interleukin (IL)-6, and single nucleotide polymorphisms (SNPs) in the AHSG gene (N = 215) at amino acid positions Thr248Met (C→T), Thr256Ser (C→G), Asp276Asn (G→A), and Arg317Cys (C→T).ResultsBoth all-cause (P < 0.001) and cardiovascular (P < 0.001) mortality were associated with low fetuin-A levels independently of age, smoking, diabetes, S-albumin, CVD, and inflammation (CRP ≥10 mg/L). Inflamed (0.199 vs. 0.247 g/L; P < 0.01) and malnourished (0.207 vs. 0.262 g/L; P < 0.05) patients had significantly lower median fetuin-A than noninflamed and well-nourished ESRD patients, respectively. In a logistic regression model (N = 101), fetuin-A was significantly (P < 0.05) associated with the presence of carotid plaques independently of age, CVD, diabetes, S-albumin, gender, and inflammation. Significant correlations were observed between fetuin-A and both S-albumin (Rho = 0.30; P < 0.0001) and IL-6 (Rho =-0.21; P < 0.01). Patients with the AHSG 256Ser allele had lower serum fetuin-A levels, and higher all-cause and cardiovascular mortality rate if they were inflamed.ConclusionThe present study shows that a low fetuin-A level is associated with malnutrition, inflammation, and atherosclerosis (carotid plaques), as well as with increased cardiovascular and all-cause mortality. Because the present study demonstrates an effect of variations in the AHSG gene on both circulating fetuin-A levels and outcome, this indicates that ESRD patients with the AHSG 256Ser allele are at risk of accelerated vascular calcification.

Encapsulating peritoneal sclerosis (EPS) is a serious complication of PD. The cause(s) of EPS are unknown but may include peritonitis and long duration of PD treatment. However, EPS may also develop in some patients without a history of peritonitis or with rather short duration of PD therapy. It has been suggested that an increasing peritoneal solute transport rate (PSTR) as a function of time on PD treatment is a risk factor for EPS development after transfer to hemodialysis, and that high PSTR is associated with an increased peritoneal microvessels surface area. Other putative mechanisms might include advanced glycated end products (AGE) and their receptors, RAGE. The purpose of this study was to investigate genetic variations in PD patients developing EPS in comparison to PD patients without EPS. SNPs in genes related to angiogenesis as well as RAGE were analyzed. Twenty patients (M/F: 12/8, mean age at start of PD 42.2 years, mean duration of PD 8.4 years) who were diagnosed as EPS during the period 1982 - 2002 at Jikei University Hospital and a matched control group (n = 20) of nonEPS PD patients were studied. The following 5 SNPs were analyzed: VEGF 936 C/T, ecNOS -786 T/C, 298 Glu/Asp, and RAGE -374 T/A, and -429 T/C. The SNPs were analyzed by the pyrosequencing method. The C allele (T/C and C/C) in the RAGE -429T/C genotype was not found in any of the EPS patients (EPS, T/T: 20/20 (100%), nonEPS, T/T: 15/20 (75%), T/C: 4/20 (20%), C/C: 1/2 0(5%), nonC allele vs C allele, p = 0.013), although every allele was found in other SNPs. We conclude that these preliminary data show that whereas genotypes directly related to angiogenesis did not differ between EPS and nonEPS patients, it is noteworthy that no patients in the EPS group had a C allele in the RAGE -429T/C genotype. This might indicate a possible genetic contribution to the development of EPS that is related to RAGE.

It is well established that materials employed for medical diagnostic and therapeutic purposes require biocompatibility testing before human use, as evidenced by the comprehensive and general guide to biocompatibility testing published in the International Standard ISO-10993 [1]. Similarly, in hemodialysis, biocompatibility profiling has become a prerequisite for any new membrane that is developed [2‐5]. This requirement has been in response to the recognition that biocompatibility may play an important role both in acute intradialytic symptoms and chronic morbidities associated with hemodialysis therapy, such as susceptibility to infection, osteodystrophy, and amyloidosis. Today, biocompatibility profiling of peritoneal dialysis (PD) solutions has become an important feature of both conventional and new dialysis solution performance [6‐11]. It is now over 20 years since the in vitro detrimental effects of commercial dialysis solution on phagocyte function were first described [12]. Since this time, there has been a plethora of reports describing a wide variety of approaches, techniques, and results of biocompatibility PD solution testing. The impetus for this proliferation of research is the growing belief that the first generation of commercially available PD solutions that have low pH, high lactate and glucose concentrations, are hyperosmolar, and contain glucose degradation products that may be causally associated with some of the complications of PD therapy [7, 8, 13‐19]. Examples of the latter are pain upon infusion in the acute setting and loss of ultrafiltration in the long-term patient. The aim of this review is to discuss definitions of biocompatibility, the hierarchical testing schemes that are often selected for biocompatibility testing, how these schemes relate to contemporary models of structural and functional alterations of the peritoneal membrane, and the associated clinical consequences. Finally, an example of how the results of such a biocompatibility testing scheme helped to

The in vitro biocompatibility performance of a 25 mmol/L bicarbonate/10 mmol/L lactate-buffered peritoneal dialysis fluid.The biocompatibility profile of a new peritoneal dialysis (PD) solution (Physioneal 35) was determined using a selection of in vitro assay systems. Physioneal 35 is buffered by a combination of 25 mmol/L bicarbonate and 10 mmol/L lactate, thereby providing a solution with a total of 35 mmol/L of alkali to complement the currently available 25 mmol/L bicarbonate and 15 mmol/L lactate combination solution, Physioneal 40. In addition, the new solution contains a calcium concentration of 1.75 mmol/L rather than 1.25 mmol/L present in Physioneal 40. Physioneal 35 and 40 are manufactured in double chamber bag systems that permit separation of glucose from the buffer during sterilization. When the two chambers are mixed just before patient use, the resulting solution has a neutral pH and reduced glucose degradation content. Physioneal 35 was evaluated for its cytotoxicity potential using a murine fibroblast assay, its acute effect on human neutrophil and human peritoneal mesothelial cell function, and its in vitro potential to form advanced glycation end products (AGE). The biocompatibility characteristics of this new formulation were compared with that of a conventional, lactate-based solution and to that of its parent formulation, Physioneal 40.Proliferation of murine fibroblasts was determined after exposure to dialysis fluids for 72 hours. Cell viability was assayed by the ability to take up neutral red dye. Human neutrophils were exposed for 15 minutes to dialysis fluids, and their ATP content and phorbol 12-myristate 13-acetate (PMA) stimulated chemiluminescence response was determined as a measure of viability and respiratory burst activity, respectively. Cellular interleukin (IL)-1beta-driven IL-8 synthesis by human mesothelial cells following acute exposure to dialysis fluids was also assessed. Advanced glycation end product formation in the dialysis fluids was measured after 5 and 20 days of incubation with human serum albumin (HSA) as the model protein.In all assays employed, the biocompatibility profile of Physioneal 35 was similar to that of the Physioneal 40 parent formulation. Physioneal 35 showed a significant improvement in biocompatibility performance compared to a pH neutralized conventional lactate-buffered peritoneal dialysis solution in the murine fibroblast assay. In the acute exposure assays, human neutrophil viability and respiratory burst were significantly improved compared with the acidic, conventional solution; however, no statistically significant improvement were seen in mesothelial cells. AGE formation, which is thought to be an important mechanism by which glucose and glucose degradation products cause structural and functional changes of the peritoneal membrane, was significantly lower in Physioneal 35 compared with the conventional dialysis solution.The biocompatibility profile of Physioneal 35 was similar to that of the original Physioneal 40 bicarbonate/ lactate-buffered dialysis solution, confirming that differences in both buffer content and calcium concentration do not affect biocompatibility performance. Both bicarbonate/lactate formulations (Physioneal 35 and Physioneal 40) were more biocompatible than a conventional lactate-buffered dialysis solution in this in vitro biocompatibility assessment.

Clinical indices of in vivo biocompatibility: The role of ex vivo cell function studies and effluent markers in peritoneal dialysis patients. Over the past 20 years, studies of the biocompatibility profile of peritoneal dialysis solutions (PDF) have evolved from initial in vitro studies assessing the impact of solutions on leukocyte function to evaluations of mesothelial cell behavior. More recent biocompatibility evaluations have involved assessments of the impact of PDF on membrane integrity and cell function in peritoneal dialysis (PD) patients. The development of ex vivo systems for the evaluation of in vivo cell function, and effluent markers of membrane integrity and inflammation in patients exposed both acutely and chronically to conventional and new PDF will be interpreted in the context of our current understanding of the biology of the dialyzed peritoneum. The available data indicate that exposure of the peritoneal environment to more biocompatible PDF is associated with improvements in peritoneal cell function, alterations in markers of membrane integrity, and reduced local inflammation. These data suggest that more biocompatible PDF will have a positive impact on host defense, peritoneal homeostasis, and the long-term preservation of peritoneal membrane function in PD patients.