Intraperitoneal heparin reduces peritoneal permeability and increases ultrafiltration in peritoneal dialysis patients

Peritoneal dialysis catheter insertion techniques by the nephrologist

Peritoneal dialysis (PD) catheter is the lifeline of PD patients, and despite the overall strength of the PD program in many countries, PD catheter survival remains the major weakness of the program. The prompt and effective implantation of the PD catheter, as well as speedy management of complications arising from catheter insertion, remains crucial for the success of the program.

Fibrosis of Peritoneal Membrane as Target of New Therapies in Peritoneal Dialysis

Peritoneal dialysis (PD) is an efficient renal replacement therapy for patients with end-stage renal disease. Even if it ensures an outcome equivalent to hemodialysis and a better quality of life, in the long-term, PD is associated with the development of peritoneal fibrosis and the consequents patient morbidity and PD technique failure. This unfavorable effect is mostly due to the bio-incompatibility of PD solution (mainly based on high glucose concentration). In the present review, we described the mechanisms and the signaling pathway that governs peritoneal fibrosis, epithelial to mesenchymal transition of mesothelial cells, and angiogenesis. Lastly, we summarize the present and future strategies for developing more biocompatible PD solutions.

How to Improve the Biocompatibility of Peritoneal Dialysis Solutions (without Jeopardizing the Patient's Health)

Peritoneal dialysis (PD) is an important, if underprescribed, modality for the treatment of patients with end-stage kidney disease. Among the barriers to its wider use are the deleterious effects of currently commercially available glucose-based PD solutions on the morphological integrity and function of the peritoneal membrane due to fibrosis. This is primarily driven by hyperglycaemia due to its effects, through multiple cytokine and transcription factor signalling-and their metabolic sequelae-on the synthesis of collagen and other extracellular membrane components. In this review, we outline these interactions and explore how novel PD solution formulations are aimed at utilizing this knowledge to minimise the complications associated with fibrosis, while maintaining adequate rates of ultrafiltration across the peritoneal membrane and preservation of patient urinary volumes. We discuss the development of a new generation of reduced-glucose PD solutions that employ a variety of osmotically active constituents and highlight the biochemical rationale underlying optimization of oxidative metabolism within the peritoneal membrane. They are aimed at achieving optimal clinical outcomes and improving the whole-body metabolic profile of patients, particularly those who are glucose-intolerant, insulin-resistant, or diabetic, and for whom daily exposure to high doses of glucose is contraindicated.

Low Molecular Weight Heparin Improves Peritoneal Ultrafiltration and Blocks Complement and Coagulation

Objectives

Clinical studies have demonstrated that the intraperitoneal (IP) complement and coagulation systems are activated in peritoneal dialysis (PD) patients. In animal models, low molecular weight heparin (LMWH) was seen to inhibit peritoneal angiogenesis, and related compounds have increased ultrafiltration volumes after repeated administration to PD patients. The present study evaluated the effects of LMWH on ultrafiltration, coagulation, and complement activation during a single PD dwell.

Design

Rats were exposed to a single dose of 20 mL 2.5% glucose-based, filter-sterilized PD fluid, with or without supplementation with LMWH. The PD fluid was administered either as an IP injection or as an infusion through an indwelling catheter. The dwell fluid was analyzed 2 hours later concerning activation of the complement and coagulation cascades, chemotactic activity, neutrophil recruitment, ultrafiltration volume, and glucose and urea concentrations.

Results

Exposure to PD fluid induced activation of IP complement [formation of C3a(desArg) and increase of C5a-dependent chemotactic activity] and coagulation (formation of thrombin–antithrombin complex) and recruitment of neutrophils. In the case of IP injection, neutrophil recruitment and complement activation were inhibited by LMWH. In both models, LMWH inhibited thrombin formation, reduced complement-dependent chemotactic activity, and increased the IP fluid volume, indicating an improved ultrafiltration.

Conclusions

The acute inflammatory reaction to PD fluid involves the complement and coagulation cascades. Addition of LMWH to the PD fluid improves ultrafiltration, inhibits formation of thrombin, and potentially blocks C5a activity. The present results motivate further investigations of the IP cascade systems in PD.

The Roles of Complement Factor C5a and CINC-1 in Glucose Transport, Ultrafiltration, and Neutrophil Recruitment during Peritoneal Dialysis

Background

In a recent experimental study, we showed that low molecular weight heparin improved ultrafiltration and blocked complement activation and coagulation in a single peritoneal dialysis (PD) dwell.

Objective

The aim of the present study was to evaluate the possible contribution of the complement factor C5a and the potential interactions between C5a, the coagulation system, and cytokines of the interleukin (IL)-8 family (cytokine-induced neutrophil chemoattractant; CINC-1).

Methods

Nonuremic rats were exposed through an indwelling catheter to a single dose of 20 mL glucose- (2.5%) based filter-sterilized PD fluid, with or without the addition of anti-rat C5 antibody. The dwell fluid was analyzed 2 and 4 hours later concerning activation of the coagulation cascades, neutrophil recruitment, ultrafiltration volume; CINC-1, glucose, urea, and histamine concentrations; and ex vivo intraperitoneal chemotactic activity.

Results

The numbers of neutrophils and levels of thrombin–antithrombin complex (TAT) and CINC-1 increased significantly during the PD dwell. C5 blockade significantly reduced the levels of TAT and increased the ultrafiltration volumes at 2 hours. Glucose concentrations were significantly positively correlated to ultrafiltration volumes.

Conclusions

Blockade of C5 leads to an increase in ultra-filtration, probably by a mechanism that involves a reduction in glucose transport. This effect may form a basis for improving PD efficiency in situations where high glucose transport limits ultrafiltration. Mechanisms connected to complement activation during PD may involve coagulation. Further studies of the intraperitoneal cascade systems under conditions of PD are indicated.

Agents that Modulate Peritoneal Membrane Structure and Function

Extensive experience with chronic peritoneal dialysis has identified a series of functional and anatomical pathologic changes in the peritoneal membrane thought to be the result of repeated insults from bioincompatible solutions. Laboratory and clinical findings from recent investigations often conflict and are difficult to interpret due to variations in methodologies, animal models, study designs, and data analyses. The principal pathophysiologic mechanisms identified thus far are oxidative stress, inflammation, and their consequences. Many substances used to neutralize the action of these insults, prevent formation of toxic compounds, or directly alter solute and water transport to improve peritoneal membrane performance have been studied. We herein review the most promising of these substances or those that deserve attention because their use has contributed to better understanding of peritoneal pathophysiology. Most peritoneal solution additives have proved useless due to their toxicity and undesirable effects, ineffectiveness, or manufacturing limitations. A few substances deserve more attention, particularly those capable of restoring negatively charged membrane sites, those that somehow improve permselectivity, scavengers of oxidants, and advanced glycation end-product inhibitors and breakers. Recent publications on clinical experience with neutral pH, low glucose degradation product (GDP) peritoneal solutions, although few and preliminary, are most encouraging. The virtual elimination of GDPs in these novel solutions will probably preclude the need for GDP scavengers and inhibitors. Nonetheless, there is room for further significant improvement in solution biocompatibility and for compounds that may restore peritoneal function.

Peritoneal Proteoglycans: Much more than Ground Substance

Recent advances in the field of glycobiology have exposed a multitude of biological processes that are controlled or influenced by proteoglycans, in both physiological and pathological conditions ranging from early embryonic development, inflammation, and fibrosis to tumor invasion and metastasis. The first part of this article reviews the biosynthesis of proteoglycans and their multifunctional roles in health and disease; the second part of this review focuses on their putative roles in peritoneal homeostasis and peritoneal inflammation and fibrosis in the context of chronic peritoneal dialysis and peritonitis.

Peritoneal Protein Loss, Leakage or Clearance in Peritoneal Dialysis, Where do we Stand?

Peritoneal protein loss (PPL) through peritoneal effluent has been a well-recognized detrimental result of peritoneal dialysis (PD) treatment since its inception. Investigation has focused mainly on PPL quantitative and qualitative determinations and evaluation of its prognostic value.

A comprehensive review of the pathophysiology of PPL (3-pore model revisited), methods of quantification, dialysate protein composition, and impact on clinical outcomes is presented herein. The author summarizes a brief analysis of associated cardiovascular disease and nutritional consequences, exploring the controversial cause-effect on mortality and technique failure.

Therapeutic modalities aiming to reduce PPL (angiotensin-converting enzyme inhibitors [ACEI]s and vitamin D therapies) were explored, although it is unclear whether PPL represents a valid therapeutic target or, on the other hand, is solely a manifestation of endothelial dysfunction.

Peritoneal Membrane Preservation

Peritoneal dialysis (PD) is a successfully used method for renal replacement therapy. However, long-term PD may be associated with peritoneal fibrosis and ultrafiltration failure. The key factors linked to their appearance are repeated episodes of inflammation associated with peritonitis and long-term exposure to bioincompatible PD fluids. Different strategies have been proposed to preserve the peritoneal membrane. This article reviews the functional and structural alterations related to PD and strategies whereby we may prevent them to preserve the peritoneal membrane. The use of new, more biocompatible, PD solutions is promising, although further morphologic studies in patients using these solutions are needed. Blockade of the renin-angiotensin-aldosterone system appears to be efficacious and strongly should be considered. Other agents have been proven in experimental studies, but most of them have not yet been tested appropriately in human beings.

Disinfection of the peritoneal dialysis bag medication port: Comparison of disinfectant agent and disinfection time

AIM

The aim of the present study was to compare different disinfection techniques for the peritoneal dialysis bag medication port (MP).

METHODS

An experimental study was conducted testing different cleaning agents (70% alcohol vs 2% chlorhexidine) and time periods (5, 10 and 60 s) for disinfection of the MP. Five microorganisms (S. aureus, E. coli, A. baumannii and C. parapsilosis, CNS) were prepared for use as contaminants of the MP. MP were incubated in Tryptic soy broth at 36°C for 24 h, after which, they were seeded on a Biomérieux blood agar plate and incubated for 24 h at 36°C.

RESULTS

Three hundred peritoneal dialysis bags were analyzed regarding the time expose to the disinfectant showed a statistically significant difference in the number of culture positive (7/100) P = 0.001; Gram positive (6/100) P = 0.006 for 5 s, one positive culture and turbid bag with 10 s, while friction for 60 s showed all negative results. The comparison between disinfectant, alcohol or chlorhexidine, 150 bag in each group, showed that the ones disinfected with alcohol had five turbid bags, eight positive cultures and seven germs identified, while all bags disinfected with chlorhexidine were negative for all parameters, with a difference statistically significant (P = 0.004).

CONCLUSION

Our results suggest that the MP should be scrubbed with 2% chlorhexidine for at least 5 s; if alcohol 70% is used the length of friction should not be inferior to 10 s.

Preventing peritoneal membrane fibrosis in peritoneal dialysis patients

Long-term peritoneal dialysis causes morphologic and functional changes in the peritoneal membrane. Although mesothelial-mesenchymal transition of peritoneal mesothelial cells is a key process leading to peritoneal fibrosis, and bioincompatible peritoneal dialysis solutions (glucose, glucose degradation products, and advanced glycation end products or a combination) are responsible for altering mesothelial cell function and proliferation, mechanisms underlying these processes remain largely unclear. Peritoneal fibrosis has 2 cooperative parts, the fibrosis process itself and the inflammation. The link between these 2 processes is frequently bidirectional, with each one inducing the other. This review outlines our current understanding about the definition and pathophysiology of peritoneal fibrosis, recent studies on key fibrogenic molecular machinery in peritoneal fibrosis, such as the role of transforming growth factor-β/Smads, transforming growth factor-β β/Smad independent pathways, and noncoding RNAs. The diagnosis of peritoneal fibrosis, including effluent biomarkers and the histopathology of a peritoneal biopsy, which is the gold standard for demonstrating peritoneal fibrosis, is introduced in detail. Several interventions for peritoneal fibrosis based on biomarkers, cytology, histology, functional studies, and antagonists are presented in this review. Recent experimental trials in animal models, including pharmacology and gene therapy, which could offer novel insights into the treatment of peritoneal fibrosis in the near future, are also discussed in depth.

Preserving the peritoneal membrane in long-term peritoneal dialysis patients

WHAT IS KNOWN AND OBJECTIVE

Peritoneal dialysis (PD) has been widely used by patients with end-stage renal disease. However, chronic exposure of the peritoneal membrane to bioincompatible PD solutions, and peritonitis and uraemia during long-term dialysis result in peritoneal membrane injury and thereby contribute to membrane changes, ultrafiltration (UF) failure, inadequate dialysis and technical failure. Therefore, preserving the peritoneal membrane is important to maintain the efficacy of PD. This article reviews the current literature on therapeutic agents for preserving the peritoneal membrane.

METHODS

A literature search of PubMed was conducted using the search terms peritoneal fibrosis, peritoneal sclerosis, membrane, integrity, preserve, therapy and peritoneal dialysis, but not including peritonitis. Published clinical trials, in vitro studies, experimental trials in animal models, meta-analyses and review articles were identified and reviewed for relevance.

RESULTS AND DISCUSSION

We focus on understanding how factors cause peritoneal membrane changes, the characteristics and mechanisms of peritoneal membrane changes in patients undergoing PD and the types of therapeutic agents for peritoneal membrane preservation. There have been many investigations into the preservation of the peritoneal membrane, including PD solution improvement, the inhibition of cytokine and growth factor expression using renin-angiotensin-aldosterone system (RAAS) blockade, glycosaminoglycans (GAGs), L-carnitine and taurine additives. In addition, there are potential future therapeutic agents that are still in experimental investigations.

WHAT IS NEW AND CONCLUSION

The efficacy of many of the therapeutic agents is uncertain because there are insufficient good-quality clinical studies. Overall membrane preservation and patient survival remain unproven in using more biocompatible PD solutions. With RAAS blockade, results are still inconclusive, as many of the clinical studies were retrospective. With GAGs, L-carnitine and taurine additives, there is no sufficiently long follow-up clinical study with a large sample size to support its efficacy. Therefore, better quality clinical studies within this area should be performed.

Low molecular weight heparin (LMWH) improves peritoneal function and inhibits peritoneal fibrosis possibly through suppression of HIF-1α, VEGF and TGF-β1

Background

Peritoneal fibrosis is the major cause of ultrafiltration failure, and intraperitoneal administration of Low Molecular Weight Heparin (LMWH) was reported to protect peritoneal function. But the exact mechanism of its influence on peritoneal structure and function is still unknown.

Methods

A fibrosis model of rat was established by intraperitoneal (IP) administration of PD fluid and Erythromycin Lactobionate. Fifty-two rats were randomly divided into 6 groups: (1) normal control group (CON, n = 6); (2) normal saline group (NS, n = 10); (3) high-glucose group (GLU, n = 10); (4) heparin group (HEP, n = 6); (5) low dose LMWH group (LLMWH, n = 10); (6) high dose LMWH group (HLMWH, n = 10). Two hour peritoneal equilibration test was performed after 28 days of intervention. The peritoneum, mesentery and omentum were harvested, and evaluated by Hematoxylin-Eosin and Masson Trichrome staining. The expressions of HIF-1α, VEGF and TGF-β1 in parietal peritoneum were detected by IHC and RT-PCR (Reverse Transcriptase Polymerase Chain Reaction).

Results

Compared with group CON and NS, ultrafiltration volume and D2/D0 glucose in group GLU decreased significantly, D/Purea (Dialysate-Plasma ratio of urea), D/Palb (Dialysate-Plasma ratio of albumin), peritoneal thickness, neoangiogenesis and inflammatory reaction increased significantly (all P<0.05). Administration of heparin and LMWH markedly alleviated these above pathological changes. The protein and mRNA levels of HIF-1α, VEGF and TGF-β1 increased significantly in group GLU, and decreased significantly after administration of LMWH in a dose-dependent manner.

Conclusions

LMWH ameliorates peritoneal function and inhibits peritoneal fibrosis, possibly through suppression of HIF-1α, VEGF and TGF-β1.

Current techniques in peritoneal dialysis

OBJECTIVE

To provide a current overview of the technique of peritoneal dialysis in dogs and cats.

CLINICAL IMPLICATION

Peritoneal dialysis is the process by which water and solutes move between blood in the peritoneal capillaries and fluid (dialysate) instilled into the peritoneal cavity, across the semipermeable membrane of the peritoneum. The primary indication for peritoneal dialysis (PD) in animals is for treatment of renal failure to correct water, solute, and acid-base abnormalities and to remove uremic toxins.

SUMMARY

Peritoneal dialysis is a modality of renal replacement therapy commonly used in human medicine for the treatment of chronic kidney disease and end-stage kidney failure. Peritoneal dialysis utilizes the peritoneum as a membrane across which fluids and uremic solutes are exchanged. Dialysate is instilled into the peritoneal cavity and, through the process of diffusion and osmosis, water, toxins, electrolytes, and other small molecules are allowed to equilibrate.

Is there a role for intraperitoneal administration of heparin in hyperthermic intraperitoneal chemotherapy (HIPEC) for peritoneal carcinomatosis of colorectal cancer origin? Current data and future orientations

In experimental studies, the intraperitoneal administration of heparin has been shown to attenuate cancer growth, reduce the formation of postoperative adhesions and possess immunomodulatory properties of oncological benefit for peritoneal carcinomatosis of colorectal cancer origin. Combined with data suggesting that the intraperitoneal administration of heparin can reduce the permeability and increase the ultrafiltration of the peritoneal membrane, we hypothesize that intraperitoneally administrated heparin could be a useful adjunction to the currently used hyperthermic intraperitoneal chemotherapy (HIPEC) regimens.

Effect of self-administered intraperitoneal bemiparin on peritoneal transport and ultrafiltration capacity in peritoneal dialysis patients with membrane dysfunction. A randomized, multi-centre open clinical trial

BACKGROUND

Progressive peritoneal membrane injury and dysfunction are feared repercussions of peritoneal dialysis (PD), and may compromise the long-term feasibility of this therapy. Different strategies have been attempted to prevent or reverse this complication with limited success.

METHODS

We performed a randomized, open multi-centre trial, aimed at scrutinizing the efficacy of self-administered intraperitoneal (i.p.) bemiparin (BM) to modulate peritoneal membrane dysfunction. The main outcome variables were peritoneal creatinine transport and the ultrafiltration (UF) capacity, estimated during consecutive peritoneal equilibration tests. The trial included a control group who did not undergo intervention. The treatment phase lasted 16 weeks with a post-study follow-up of 8 weeks.

RESULTS

Intraperitoneal BM did not significantly improve creatinine transport or the UF capacity, when the whole group was considered. However, we observed a time-limited improvement in the UF capacity for the subgroup of patients with overt UF failure, which was not observed in the control group. Intraperitoneal injection of BM did not carry an increased risk of peritoneal infection or major haemorrhagic complications.

CONCLUSIONS

Our data do not support the systematic use of BM for management of peritoneal membrane dysfunction in PD patients. Further studies on the usefulness of this approach in patients with overt UF failure are warranted. Intraperitoneal administration of BM is safe in PD patients, provided regulated procedures are respected.

Long-term Intervention with Heparins in a Rat Model of Peritoneal Dialysis

Background

Peritoneal dialysis (PD) is associated with functional and structural alterations of the peritoneal membrane, particularly new vessel formation and fibrosis. In addition to anticoagulant effects, heparin displays anti-inflammatory and angiostatic properties. Therefore, the effects of administration of heparins on function and morphology of the peritoneal membrane were studied in a rat PD model.

Methods

Rats received 10 mL conventional PD fluid (PDF) daily, with or without the addition of unfractionated heparin (UFH) or low molecular weight heparin (LMWH) in the PDF (1 mg/10 mL intraperitoneally) via a mini access port. Untreated rats served as controls. After 5 weeks, a 90-minute functional peritoneal transport test was performed and tissues and peritoneal leukocytes were taken.

Results

PD treatment induced loss of ultrafiltration ( p < 0.01), a twofold increase in glucose absorption ( p < 0.03), increased urea transport ( p < 0.02), and loss of sodium sieving ( p < 0.03), which were also found in the PDF + heparin groups. Increased peritoneal cell influx and hyaluronan production ( p < 0.02) as well as an exchange of mast cells and eosinophils for neutrophils after PD treatment were observed in PD rats; addition of heparin did not affect those changes. Mesothelial regeneration, submesothelial blood vessel and matrix formation, and accumulation of tissue macrophages were seen in PD animals. Spindle-shaped vimentin-positive and cytokeratin-negative cells indicated either partial injury and denudation of mesothelial cells or epithelial-to-mesenchymal transition. Neither UFH nor LMWH affected any of these morphological changes.

Conclusion

Within 5 weeks, PD treatment induces a chronic inflammatory condition in the peritoneum, evidenced by high transport, leukocyte recruitment, tissue remodeling, and induction of spindle-shaped cells in the mesothelium. Addition of LMWH or UFH to the PDF did not prevent these adverse PDF-induced peritoneal changes.

Citrate supplementation of PD fluid: effects on net ultrafiltration and clearance of small solutes in single dwells

BACKGROUND

Inflammatory reactions affect the general performance as well as the technique survival of peritoneal dialysis (PD). Anti-inflammatory additives like heparin and sodium citrate have shown favourable results in these respects. The present study is the first to evaluate citrate-supplemented PD fluids (PDFs) in humans.

METHODS

Crossover design was used to evaluate sodium citrate and heparin-supplemented Gambrosol Trio (2.5% glucose) in 28 stable outpatients from the PD unit. Comparisons were made between single dwells of each fluid. Citrate supplementation at 5 mM/L was compared with standard PDF, and citrate supplementation at 10 mM/L was compared with low-molecular-weight heparin (4500 units of tinzaparin) supplementation and standard PDF. The initial osmolarity of the fluids was equalized by adding sodium chloride.

RESULTS

Citrate supplementation at 5 mM/L significantly increased net ultrafiltration, measured as drained volume gain, by 126 mL. Creatinine and phosphate clearance, but not glucose clearance, was significantly improved by supplementation with citrate or heparin. Heparin supplementation created an insignificant trend towards an increased ultrafiltration (P = 0.08). No negative side effects were reported for any of the treatments; however, citrate supplementation led to a small calcium loss by the drained PD fluid (0.4 mmol) and a transient fall in the plasma concentration (0.04 mM/L) of free calcium ions at 5 mM/L citrate. Effects on plasma bicarbonate concentration were insignificant.

CONCLUSIONS

Citrate supplementation of PD fluid improved ultrafiltration and clearance of small solutes with only minor effects on calcium turnover. The mechanism is unknown and, according to the results, not related to complement inhibition.

Comparison of intraperitoneal antithrombin III and heparin in experimental peritonitis

The antifibrotic effect of heparin, an anticoagulant used routinely in the treatment of peritonitis, is unknown, whereas antithrombin III (AT-III) has both anticoagulant and anti-inflammatory actions. The aim of this study was to compare the antifibrotic and anti-inflammatory effects of AT-III and heparin in rats with experimentally developed peritonitis while on peritoneal dialysis (PD). Sixty-four Wistar albino rats (in four groups of 16) were used in the study. Group 1 received PD solution only, group 2 had experimentally developed peritonitis in addition to PD solution; group 3 received heparin intraperitoneally for 3 days, in addition to group 2; and group 4 received AT-III intraperitoneally for 3 days, in addition to group 2. Plasma and dialysate levels of tissue-plasminogen activator were similar in heparin and AT-III groups on both day 3 and day 14. The inflammation scores of heparin and AT-III groups were also similar in both early and late phases. The fibrosis score of the AT-III group was low compared with both peritonitis and heparin groups in the early phase (p = 0.03), though it was similar in the late phase. The effects of AT-III are comparable with that of heparin in PD peritonitis in rats with experimentally developed peritonitis while on PD.

Epithelial-to-mesenchymal transition of mesothelial cells is an early event during peritoneal dialysis and is associated with high peritoneal transport

Ultrafiltration (UF) failure is a consequence of long-term peritoneal dialysis (PD). Fibrosis, angiogenesis, and vasculopathy are causes of this functional disorder after 3-8 years on PD. Epithelial-to-mesenchymal transition (EMT) of mesothelial cell (MC) is a key process leading to peritoneal fibrosis with functional deterioration. Our purpose was to study the peritoneal anatomical changes during the first months on PD, and to correlate them with peritoneal functional parameters. We studied 35 stable PD patients for up to 2 years on PD, with a mean age of 45.3+/-14.5 years. Seventy-four percent of patients presented loss of the mesothelial layer, 46% fibrosis (>150 microm) and 17% in situ evidence of EMT (submesothelial cytokeratin staining), which increased over time. All patients with EMT showed myofibroblasts, while only 36% of patients without EMT had myofibroblasts. The number of peritoneal vessels did not vary when we compared different times on PD. Vasculopathy was present in 17% of the samples. Functional studies were used to define the peritoneal transport status. Patients in the highest quartile of mass transfer area coefficient of creatinine (Cr-MTAC) (>11.8 ml min(-1)) showed significantly higher EMT prevalence (P=0.016) but similar number of peritoneal vessels. In the multivariate analysis, the highest quartile of Cr-MTAC remained as an independent factor predicting the presence of EMT (odds ratio 12.4; confidence interval: 1.6-92; P=0.013) after adjusting for fibrosis (P=0.018). We concluded that, during the first 2 PD years, EMT of MCs is a frequent morphological change in the peritoneal membrane. High solute transport status is associated with its presence but not with increased number of peritoneal vessels.

Pleiotropic Effects of Heparin and Heparinoids in Peritoneal Dialysis

Unfractionated heparin, low-molecular-weight heparins, and sulodexide belong to the family of glycosaminoglycans. Recent studies report on properties other than anticoagulant activities of these medications. They include modulation of cell growth and proliferation via actions on numerous growth factors affecting the immune system and matrix molecules production and degradation. Long-term peritoneal dialysis remarkably influences peritoneal cavity homeostasis by mechanisms mediated by growth factors. They initiate progression of pathological processes and further account for morphological and functional alterations of the peritoneal membrane. The best-recognized pathologies in peritoneal cavity under these conditions encompass inflammation, fibrosis, and vasculopathy, often leading to fatal encapsulating peritoneal sclerosis. Intraperitoneal heparin and its derivatives, by their pleiotropic actions, may influence these crucial processes and improve the peritoneal dialysis technique survival in a complex and so far understudied way. These issues, novel medical approaches, and their likely mechanisms have been reviewed.

Glucotoxicity in peritoneal dialysis--solutions for the solution!

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.

Favourable modulation of the inflammatory changes in hypercholesterolemic atherogenesis by a low-molecular-weight heparin derivative

BACKGROUND

In the hypercholesterolemic state, the net result of combined oxidative and nitrosative stress is a pro-inflammatory phenotype that is manifested as increased adhesion molecule expression, enhanced leucocyte trafficking, and increased vascular permeability. The present work explores the inflammatory aspects of hypercholesterolemic atherogenesis, and also evaluates the role of a low-molecular-weight heparin derivative (LMWH), Certoparin, on a biochemical basis.

METHODS AND RESULTS

Two groups of male Wistar rats were fed an atherogenic diet (normal rat chow plus 4% cholesterol, 1% cholic acid and 0.5% thiouracil-CCT diet) for 2 weeks. While one was left untreated, the other was administered LMWH (300 microg/day/rat commencing on day 8 and continued for a week). Increased concentrations of plasma C-reactive protein and fibrinogen and cardiac TNF-alpha indicated severe inflammation in the atherogenic diet fed rats. In comparison, these biochemical indices of inflammation diminished significantly in the LMWH treated group (p < 0.001). Significant depletion of thiols, along with accentuated activities of the glutathione metabolising was observed in the cardiac and hepatic tissues of the untreated atherogenic rats, indicating heightened oxidative response. Tissue damage was marked by elevated levels of plasma and tissue hexose, hexosamine, hexuronic acid and sialic acid, which were reversed towards normalcy on LMWH administration. The activities of lysosomal enzymes (N-acetyl glucosaminidase, beta-glucuronidase, beta-galactosaminidase and cathepsin-D) showed a marked increase in the CCT-diet fed rats, while LMWH treated rats showed normal activities (p < 0.001). The osmotic fragility test revealed that the untreated hyperlipidemic rat erythrocytes were significantly fragile at high salt concentrations, while the response was normalized in the LMWH treated group (p < 0.05). Further, hypercholesterolemia induced downregulation of physiological nitric oxide levels was corrected upon treatment with heparin-derivative.

CONCLUSION

The results of this work highlight the inflammatory changes in atherogenic conditions and that the low-molecular-weight heparin derivative affords substantial protection.

Biochemical evaluation of the inflammatory changes in cardiac, hepatic and renal tissues of adriamycin-administered rats and the modulatory role of exogenous heparin-derivative treatment

The aim of the present work is to evaluate the role of a heparin derivative, low molecular weight heparin (LMWH), certoparin on the inflammatory changes in adriamycin (ADR) cytotoxicity on a biochemical basis. Male Wistar rats (140+/-10g) were divided into four groups: untreated control, ADR group (a single dose intravenous injection of 7.5 mg/kg ADR), LMWH control (300 microg/(day rat) s.c. for 1 week) and ADR plus LMWH group (7.5 mg/kg ADR on day 1 of study period followed by LMWH treatment, 300 microg/(day rat) commencing on day 8 and continued for 1 week). At the end of the 2-week experimental period, biochemical assessment of the inflammatory status was carried out in the plasma, cardiac, hepatic and renal tissues. Increased concentrations of plasma C-reactive protein (CRP) and fibrinogen indicated severe inflammation in the ADR cytotoxic rats. These acute-phase inflammatory markers diminished significantly in the LMWH treated group, when compared with the cytotoxic group (p<0.001). Tissue damage was marked by elevated levels of plasma and tissue hexose, hexosamine, hexuronic acid and sialic acid, which were reversed on LMWH administration (p<0.001). The activities of lysosomal enzymes was measured in the experimental groups, and it was observed that the ADR induced rats showed a marked increase in the enzymic activities, while LMWH treated rats revealed normal activities. The present study throws light on the inflammatory changes in the ADR-challenged heart, liver and kidney tissues, and projects the biochemical basis for the anti-inflammatory property of the LMWH, certoparin.

Encapsulating peritoneal sclerosis

Since the first peritoneal dialysis (PD) patients with encapsulating peritoneal sclerosis (EPS) were reported in 1980, EPS has been considered primarily a fatal complication. The incidence of EPS in PD patients has been reported to be from 0.7% to 7.3%, and the rate appears to be higher in patients receiving long-term treatment. Most data from Japan has shown an overall incidence of 2.5% with an evident negative effect of increasing duration of PD, which also augments mortality. Since EPS occurred after withdrawal from PD in more than half of the patients, strict monitoring is necessary when a long-term PD patient is withdrawn from PD. Maintaining patients on standard PD for more than 8 years using conventional solutions is associated with a substantial risk for development of EPS. Appropriate treatment according to the disease stage is most important in EPS treatment. Therefore, when examining a PD patient complaining of gastrointestinal symptoms, the possibility of EPS has to be kept in mind. Basic therapeutic tactics for EPS include appropriate use of steroids. If the state of bowel obstruction persists, laparotomy and enterolysis should be performed to obtain a complete cure. It is now recognized that EPS is not a fatal complication of PD.

A high peritoneal large pore fluid flux causes hypoalbuminaemia and is a risk factor for death in peritoneal dialysis patients

BACKGROUND

Hypoalbuminaemia is common in peritoneal dialysis (PD) patients and has an associated high mortality. An excess morbidity and mortality has previously been found in patients with high peritoneal transport. A high peritoneal large pore fluid flux (Jv(L)) results in increased peritoneal loss of protein that possibly contributes to patient morbidity. Alternatively, hypoalbuminaemia and high transport status could be just a marker of capillary pathology associated with atherosclerotic comorbidity.

METHODS

Peritoneal dialysis capacity computer modelling of peritoneal transport, based on Rippe's three-pore model, was performed to measure Jv(L) in 155 incident PD patients 2-4 weeks after PD initiation. Patient clinical and biochemical status was determined -6, -3, -1, 1 and 6 months after PD initiation, and every 6 months thereafter. Jv(L) was redetermined in prevalent patients 2 and 4 years after PD initiation.

RESULTS

Jv(L) was 0.106+/-0.056 ml/min/1.73 m(2) (median 0.094, interquartile range 0.068-0.128). It was correlated to age*** (*P<0.05; **P<0.01; ***P<0.001) (20-30 years 0.079+/-0.04; 70 years 0.121+/-0.071), but not to gender. No correlation to diabetic or preexisting renal replacement therapy was seen, but patients with atherosclerosis had higher Jv(L) (0.123+/-0.06 vs 0.100+/-0.056*) as had patients with other systemic disease (0.121+/-0.68 vs 0.100+/-0.051*). Jv(L) was positively correlated to area parameter (r = 0.41***), and negatively correlated to plasma albumin (-0.36***). Patients were divided into three equal groups: group 1, Jv(L) <0.075 ml/min/1.73 m(2); group 2, 0.075-0.11; group 3: >0.11. There was no difference between the groups in p-albumin prior to PD. Immediately after PD start, differences between the three groups appeared (1 month p-albumin: (micromol/l) group 1, 548+/-83; group 2, 533+/-86; group 3, 497+/-78**), and persisted for up to 6 years. No significant change in Jv(L) was seen at 2 and 4 years. Patients with significant albuminuria also had hypoalbuminaemia (<1 g/day: 546+/-81 mumol/l; >2 g/day: 503+/-54 micromol/l). Intermittent PD ameliorated the effect of Jv(L) on albumin losses and clearance. Mortality was increased significantly with raised Jv(L), independently of age (2 year mortality: group 1, 10%, group 3, 32%*). There was no overall effect on technique survival, but hypoalbuminaemic group 3 patients had a higher failure rate.

CONCLUSION

Jv(L) is related to hypoalbuminaemia and mortality after PD initiation. A high Jv(L) seems to be a marker of preexisting vascular pathology, and to cause hypoalbuminaemia after PD initiation. It is suggested that peritoneal albumin loss can have an identical pathogenic effect as urinary albumin loss, by causing an iatrogenic "nephrotic" syndrome.

The pathogenesis and therapeutic option of encapsulating peritoneal sclerosis

Since the first peritoneal dialysis (PD) patients with encapsulating peritoneal sclerosis (EPS) were reported in 1980, EPS has been considered primarily a fatal complication. The incidence of EPS in PD patients has been reported to be from 0.7% to 7.3%, and the rate appears to be higher in patients receiving long-term treatment. Most data from Japan has shown an overall incidence of 2.5% with an evident negative effect of increasing duration of PD, which also augments mortality. Since EPS occurred after withdrawal from PD in more than half of the patients, strict monitoring is necessary when a long-term PD patient is withdrawn from PD. Maintaining patients on standard PD for more than 8 years using conventional solutions is associated with a substantial risk for development of EPS. Appropriate treatment according to the disease stage is most important in EPS treatment. Therefore, when examining a PD patient complaining of gastrointestinal symptoms, the possibility of EPS has to be kept in mind. Basic therapeutic tactics for EPS include an appropriate use of steroids. If the state of bowel obstruction persists, laparotomy and enterolysis should be performed to obtain complete cure. It is now recognized that EPS is not a fatal complication of PD.

Intraperitoneal heparin ameliorates the systemic inflammatory response in PD patients

BACKGROUND

Patients with end-stage renal disease (ESRD) suffer from high mortality rates of cardiovascular diseases, conditions closely linked to the magnitude of their chronic low-grade inflammation. As heparins have been suggested to possess anti-inflammatory properties, we set out to investigate the impact of long-term treatment with intraperitoneal heparin on local and systemic inflammation in peritoneal dialysis (PD) patients.

METHODS

In a double-blinded cross-over study, 21 PD patients with ESRD were randomised to inject either 4,500 anti-Xa IU tinzaparin or placebo (isotonic saline) into their morning dialysis bags every day for two periods of 3 months separated by a 1-month wash-out period. Blood and dialysate samples were analysed for inflammatory markers at the start and end of each treatment period. In dialysate, the appearance rates of the inflammatory markers were calculated to adjust for ultrafiltration variations.

RESULTS

Eleven patients completed the trial. Treatment with intraperitoneal tinzaparin was accompanied with a median 25.8% reduction of the plasma C-reactive protein concentration (p = 0.032), a 7.3% reduction of the plasma fibrinogen concentration (p = 0.042) and a 54.5% reduction of the dialysate interleukin 6 appearance rate (p = 0.007) compared with placebo.

CONCLUSION

Long-term treatment with intraperitoneal tinzaparin of ESRD patients on PD reduces local and systemic concentrations of inflammatory markers.