Plasma levels of advanced glycation end products during haemodialysis, haemodiafiltration and haemofiltration: potential importance of dialysate quality

Receptor for Advanced Glycation End Product, Organ Crosstalk, and Pathomechanism Targets for Comprehensive Molecular Therapeutics in Diabetic Ischemic Stroke

Diabetes mellitus, a well-established risk factor for stroke, is related to higher mortality and poorer outcomes following the stroke event. Advanced glycation end products(AGEs), their receptors RAGEs, other ligands, and several other processes contribute to the cerebrovascular pathomechanism interaction in the diabetes-ischemic stroke combination. Critical reappraisal of molecular targets and therapeutic agents to mitigate them is required to identify key elements for therapeutic interventions that may improve patient outcomes. This scoping review maps evidence on the key roles of AGEs, RAGEs, other ligands such as Leukotriene B4 (LTB4), High-mobility group box 1 (HMGB1) nuclear protein, brain-kidney-muscle crosstalk, alternate pathomechanisms in neurodegeneration, and cognitive decline related to diabetic ischemic stroke. RAGE, HMGB1, nitric oxide, and polyamine mechanisms are important therapeutic targets, inflicting common consequences of neuroinflammation and oxidative stress. Experimental findings on a number of existing-emerging therapeutic agents and natural compounds against key targets are promising. The lack of large clinical trials with adequate follow-up periods is a gap that requires addressing to validate the emerging therapeutic agents. Five therapeutic components, which include agents to mitigate the AGE-RAGE axis, improved biomarkers for risk stratification, better renal dysfunction management, adjunctive anti-inflammatory-antioxidant therapies, and innovative neuromuscular stimulation for rehabilitation, are identified. A comprehensive therapeutic strategy that features all the identified components is needed for outcome improvement in diabetic stroke patients.

Comparative efficacy between hemodialysis using super high-flux dialyzer with hemoperfusion and high-volume postdilution online hemodiafiltration in removing protein bound and middle molecule uremic toxins: A cross-over randomized controlled trial

BACKGROUND

Hemodialysis (HD) using super high-flux dialyzer (HD + SHF) comparably removed uremic toxins to high-volume postdilution online hemodiafiltration (olHDF). Integration of hemoperfusion (HP) to HD + SHF (HD + SHF + HP) might provide superior uremic toxin removing capability to high-volume postdilution olHDF.

METHOD

The present study was conducted in thrice-a-week HD patients to compare the efficacy in removing indoxyl sulfate (IS), beta-2 microglobulin (β₂ M), and urea between high-volume postdilution ol-HDF and HD + SHF + HP, comprising HD + SHF as the main treatment plus HD + SHF + HP 1/week in the first 4 weeks and 1/2 weeks in the second 4 weeks.

RESULTS

Ten prevalent HD patients with blood flow rate (BFR) above 400 ml/min were randomized into two sequences of 8-week treatment periods of HD + SHF + HP and later high-volume postdilution olHDF or vice versa. When compared with high-volume postdilution olHDF (convective volume of 26.02 ± 1.8 L/session), HD + SHF + HP provided comparable values of percentage reduction ratio of IS (52.0 ± 11.7 vs. 56.3 ± 7.5%, p = 0.14) and β₂ M (83.7 ± 4.9 vs. 84.0 ± 4.3%, p = 0.37) and slightly lower urea reduction ratio. Despite greater dialysate albumin loss (p = 0.008), there was no significant change in serum albumin level in HD + SHF + HP group.

CONCLUSIONS

HD + SHF + HP could not provide superior efficacy in removing uremic toxins to high-volume postdilution olHDF. The use of low BFR of 200 ml/min during the first 2 h of HD + SHF + HP session, according to the instruction of manufacturer, might impair the efficacy of the HD + SHF part in removing uremic toxins.

Removal of Urea, β2-Microglobulin, and Indoxyl Sulfate Assessed by Absorbance and Fluorescence in the Spent Dialysate During Hemodialysis

In this study, simultaneous removal assessment of marker molecules from three uremic toxin groups was performed during different hemodialysis treatment modalities using optical characteristics of spent dialysate. Results from optical measurements were compared with the results from chemical laboratory. Ten chronic dialysis patients, mean age 59 ± 15 years, were included in the study during 40 hemodialysis sessions. Low-flux hemodialysis (HD), high-flux hemodialysis (HF), and postdilutional online hemodiafiltration (HDF) with different settings were used. The reduction ratio (RR) and total removed solute (TRS) of three uremic solutes were determined: small molecular weight urea, middle molecular β2-microglobulin (B2M), and protein-bound indoxyl sulfate (IS). Concentrations of these solutes in the spent dialysate were measured by laboratory (lab) and optical (opt) methods, in the serum by laboratory methods, and calculated RR values in percentage were compared accordingly. Total removed solute was obtained from the total dialysate collection (TDC) using lab and opt methods. The highest RR values were found for urea and B2M, and the lowest for IS. The difference between RR of lab and opt results estimated as mean accuracy (BIAS) was ≤8.1% for all three solutes. Good correspondence between TRS lab vs. opt was achieved, resulting in strong linear correlation values R from 0.727 for urea to 0.971 for IS. Accuracy for TRS values as BIAS ± standard error (SE), comparing lab vs. opt, showed no statistical difference for any of the observed uremic solutes (P > 0.05). The accuracy of the optical method was not influenced by the dialysis modality (HD, HF, and HDF).

Hemodialysis biomarkers: total advanced glycation end products (AGEs) against oxidized human serum albumin (HSAox)

AIMS

Nephropathic patients show higher levels of advanced glycation end products (AGEs) and oxidized human serum albumin (HSAox) compared to healthy subjects. These two classes of compounds are formed as the result of oxidative insults; for this reason, they can be useful oxidative stress biomarkers. The present study examines the variation of AGEs and HSAox in hemodialysis (HD) patients before and after dialysis session, evaluating the impact of different dialytic techniques and filters on their removal.

METHODS

A total of 50 healthy subjects (control group) and 130 HD patients were enrolled in the study. Hemodialysis patients were subdivided based on dialytic techniques: 109 in diffusive technique and 22 in convective technique. We monitored HSAox, AGEs and other laboratory parameters at early morning in healthy subjects and in HD patients before and after the dialysis procedures.

RESULTS

The level of HSAox decreases after a single dialytic session (from 58.5 ± 8.8% to 41.5 ± 11.1%), but the concentration of total AGEs increases regardless of adopted dialytic techniques (from 6.8 ± 5.2 µg/ml to 9.2 ± 4.4 µg/ml). In our study, levels of HSAox and total AGEs are similar in diabetic and non-diabetic HD patients. The increase in total AGEs after dialysis was only observed using polysulfone filters but was absent with polymethacrylate filters.

CONCLUSIONS

HSAox is a simple and immediate method to verify the beneficial effect of a single dialysis session on the redox imbalance, always present in HD patients. Total AGEs assayed by ELISA procedure seem to be a less reliable biomarker in this population.

Effectiveness of arginase inhibitors against experimentally induced stroke

Stroke is a lethal disease, but it disables more than it kills. Stroke is the second leading cause of death and the most frequent cause of permanent disability in adults worldwide, with 90% of survivors having residual deficits. The pathophysiology of stroke is complex and involves a strong inflammatory response associated with oxidative stress and activation of several proteolytic enzymes. The current study was designed to investigate the effect of arginase inhibitors (L-citruline and L-ornithine) against ischemic stroke induced in rats by middle cerebral artery occlusion (MCAO). MCAO resulted in alteration in rat behavior, brain infarct, and edema associated with disruption of the blood-brain barrier (BBB). This was mediated through overexpression of arginase I and II, inducible NOS (iNOS), malondialdehyde (MDA), advanced glycation end products (AGEs), TNF-α, and IL-1β and downregulation of endothelial nitric oxide synthase (eNOS). Treatment with L-citruline and L-ornithine and the standard neuroprotective drug cerebrolysin ameliorated all the deleterious effects of stroke. These results indicate the possible use of arginase inhibitors in the treatment of stroke after suitable clinical trials are done.

Cardiovascular Risk in Hemodialysis Patients: A Mechanistic Approach

A new formula is proposed to express the excess burden of cardiovascular risk faced by hemodialysis patients as a function of various inherent, acquired and potentially modifiable factors. The proposed equation CVRHD = CVRB X f(([CKD+HD]/[HDtech+Dr])+X) includes the terms: CVRHD (cardiovascular risk in hemodialysis patients); CVRB (baseline cardiovascular risk); CKD (risk associated with chronic kidney disease); HD (risks associated with the process of hemodialysis); HDtech (benefits of new hemodialysis technologies); Dr (benefits of drug therapies) and X (unknown or putative factors influencing cardiovascular morbidity).

We review the various factors included in this proposed formula, touching upon the epidemiology, pathophysiology and therapeutic implications, including possible strategies to modify risk. As is apparent from the formula, CKD and HD in particular act as risk multipliers in augmenting or amplifying the baseline cardiovascular risk, while new hemodialysis technologies may provide an opportunity for “cardioprotective dialysis.” Drug treatment may serve to mitigate some of the risk unique to this population.

Red blood cell abnormalities and the pathogenesis of anemia in end-stage renal disease

Anemia is the most common hematologic complication in end-stage renal disease (ESRD). It is ascribed to decreased erythropoietin production, shortened red blood cell (RBC) lifespan, and inflammation. Uremic toxins severely affect RBC lifespan; however, the implicated molecular pathways are poorly understood. Moreover, current management of anemia in ESRD is controversial due to the "anemia paradox" phenomenon, which underlines the need for a more individualized approach to therapy. RBCs imprint the adverse effects of uremic, inflammatory, and oxidative stresses in a context of structural and functional deterioration that is associated with RBC removal signaling and morbidity risk. RBCs circulate in hostile plasma by raising elegant homeostatic defenses. Variability in primary defect, co-morbidity, and therapeutic approaches add complexity to the pathophysiological background of the anemic ESRD patient. Several blood components have been suggested as biomarkers of anemia-related morbidity and mortality risk in ESRD. However, a holistic view of blood cell and plasma modifications through integrated omics approaches and high-throughput studies might assist the development of new diagnostic tests and therapies that will target the underlying pathophysiologic processes of ESRD anemia.

Comparing Changes in Plasma and Skin Autofluorescence in Low-Flux versus High-Flux Hemodialysis

Background

Tissue advanced glycation end products (AGE) are increased in hemodialysis (HD) patients, especially those with cardiovascular complications. Skin autofluorescence (skin-AF) can noninvasively estimate the accumulation of AGE in tissue. The aim was to clarify whether HD using a high-flux (HF) dialyzer favors plasma- or skin-AF removal compared to low-flux (LF) dialysis.

Material and methods

28 patients were treated with either an HF-HD or LF-HD but otherwise unchanged conditions in a cross-over design. A glucose containing dialysate was used. Skin-AF was measured noninvasively with an AGE reader before and after HD. Fluorescence (370 nm/465 nm) of plasma (p-AF) was determined as total and nonprotein-bound fractions. Correction for hemoconcentrations were made using the change in serum albumin. Paired and nonpaired statistical analyses were used.

Results

Skin-AF was unchanged after LF- and HF-dialysis. Total, free, and protein- bound p-AF was reduced after a single LF-HD by 21%, 28%, and 17%, respectively ( P<.001). After HF HD total and free p-AF was reduced by 5% and 15%, respectively ( P<.001), while protein bound values were unchanged. The LF-HD resulted in a more pronounced reduction of p-AF than did HF HD ( P<.001). Serum albumin correlated inversely with p-AF in HF-HD.

Conclusions

In the dialysis settings used there was no significant change in skin AF after dialysis, with LF or with HF dialysis. Although only limited reduction in plasma fluorescence was observed, this was more pronounced when performing LF dialysis. These data are not in overwhelming support of the use of HF dialysis in the setting used in this study.

Haemodiafiltration, haemofiltration and haemodialysis for end-stage kidney disease

BACKGROUND

Convective dialysis modalities (haemofiltration (HF), haemodiafiltration (HDF), and acetate-free biofiltration (AFB)) removed excess body fluid across the dialysis membrane with positive pressure and accumulated middle- and larger-size accumulated solutes more efficiently than haemodialysis (HD). This increased larger solute removal combined with use of ultra-pure dialysis fluid in convective dialysis is hypothesised to reduce the frequency and severity of symptoms during dialysis as well as improve clinical outcomes. Convective dialysis therapies (HDF and HF) are associated with lower mortality compared to diffusive therapy (HD) in observational studies. This is an update of a review first published in 2006.

OBJECTIVES

To compare convective (HF, HDF, or AFB) with diffusive (HD) dialysis modalities on clinical outcomes (mortality, major cardiovascular events, hospitalisation and treatment-related adverse events) in men and women with end-stage kidney disease (ESKD).

SEARCH METHODS

We searched the Cochrane Renal Group's Specialised Register (to 18 February 2015) through contact with a Trials' Search Co-ordinator using search terms relevant to this review.

SELECTION CRITERIA

We included randomised controlled trials comparing convective therapy (HF, HDF, AFB) with another convective therapy or diffusive therapy (HD) for treatment of ESKD.

DATA COLLECTION AND ANALYSIS

Two independent authors identified studies, extracted data and assessed study risk of bias. We summarised treatment effects using the random effects model. We reported results as a risk ratio (RR) for dichotomous outcomes and mean difference (MD) for continuous data together with 95% confidence intervals (CI). We assessed for heterogeneity using the Chi(2) test and explored the amount of variation in treatment estimates beyond that expected by chance using the I(2) statistic.

MAIN RESULTS

Twenty studies comprising 667 participants were included in the 2006 review. In that review, there was insufficient evidence of treatment effects on major clinical outcomes to draw clinically meaningful conclusions. Searching to February 2015 identified 40 eligible studies comprising 3483 participants overall. In total, 35 studies (4039 participants) compared HF, HDF or AFB with HD, three studies (54 participants) compared AFB with HDF, and three studies (129 participants) compared HDF with HF.Risks of bias in all studies were generally high resulting in low confidence in estimated treatment effects. Convective dialysis had no significant effect on all-cause mortality (11 studies, 3396 participants: RR 0.87, 95% CI 0.72 to 1.05; I(2) = 34%), but significantly reduced cardiovascular mortality (6 studies, 2889 participants: RR 0.75, 95% CI 0.61 to 0.92; I(2) = 0%). One study reported no significant effect on rates of nonfatal cardiovascular events (714 participants: RR 1.14, 95% CI 0.86 to 1.50) and two studies showed no significant difference in hospitalisation (2 studies, 1688 participants: RR 1.23, 95% CI 0.93 to 1.63; I(2) = 0%). One study reported rates of hypotension during dialysis were significantly reduced with convective therapy (906 participants: RR 0.72, 95% CI 0.66 to 0.80). Adverse events were not systematically evaluated in most studies and data for health-related quality of life were sparse. Convective therapies significantly reduced predialysis levels of B2 microglobulin (12 studies, 1813 participants: MD -5.55 mg/dL, 95% CI -9.11 to -1.98; I(2) = 94%) and increased dialysis dose (Kt/V urea) (14 studies, 2022 participants: MD 0.07, 95% CI -0.00 to 0.14; I(2) = 90%) compared to diffusive therapy, but results across studies were very heterogeneous. Sensitivity analyses limited to studies comparing HDF with HD showed very similar results. Directly comparative data for differing types of convective dialysis were insufficient to draw conclusions.Studies had important risks of bias leading to low confidence in the summary estimates and were generally limited to patients who had adequate dialysis vascular access.

AUTHORS' CONCLUSIONS

Convective dialysis may reduce cardiovascular but not all-cause mortality and effects on nonfatal cardiovascular events and hospitalisation are inconclusive. However, any treatment benefits of convective dialysis on all patient outcomes including cardiovascular death are unreliable due to limitations in study methods and reporting. Future studies which assess treatment effects of convection dose on patient outcomes including mortality and cardiovascular events would be informative.

Protein-bound uraemic toxins, dicarbonyl stress and advanced glycation end products in conventional and extended haemodialysis and haemodiafiltration

BACKGROUND

Protein-bound uraemic toxins (PBUT), dicarbonyl stress and advanced glycation end products (AGEs) associate with cardiovascular disease in dialysis. Intensive haemodialysis (HD) may have significant clinical benefits. The aim of this study was to evaluate the acute effects of conventional and extended HD and haemodiafiltration (HDF) on reduction ratio (RR) and total solute removal (TSR) of PBUT, dicarbonyl stress compounds and AGEs.

METHODS

Thirteen stable conventional HD patients randomly completed a single study of 4-h HD (HD4), 4-h HDF (HDF4), 8-h HD (HD8) and 8-h HDF (HDF8) with a 2-week interval between the study sessions. RR and TSR of PBUT [indoxyl sulphate (IS), p-cresyl sulphate (PCS), p-cresyl glucuronide, 3-carboxyl-4-methyl-5-propyl-2-furanpropionic acid (CMPF), indole-3-acetic acid (IAA) and hippuric acid] of free and protein-bound AGEs [N(ε)-(carboxymethyl)lysine (CML), N(ε)-(carboxyethyl)lysine (CEL), Nδ-(5-hydro-5-methyl-4-imidazolon-2-yl)-ornithine, pentosidine], as well as of dicarbonyl compounds [glyoxal, methylglyoxal, 3-deoxyglucosone], were determined.

RESULTS

Compared with HD4, HDF4 resulted in increased RR of total and/or free fractions of IAA and IS as well as increased RR of free CML and CEL. HD8 and HDF8 showed a further increase in TSR and RR of PBUT (except CMPF), as well as of dicarbonyl stress and free AGEs compared with HD4 and HDF4. Compared with HD8, HDF8 only significantly increased RR of total and free IAA and free PCS, as well as RR of free CEL.

CONCLUSIONS

Dialysis time extension (HD8 and HDF8) optimized TSR and RR of PBUT, dicarbonyl stress and AGEs, whereas HDF8 was superior to HD8 for only a few compounds.

The low AGE diet: a neglected aspect of clinical nephrology practice?

Increasing evidence in the literature suggests an important role for advanced glycation end products (AGEs) in the generation of a state of increased oxidative stress and chronic subclinical inflammation, which underlies most modern chronic diseases, including diabetes, cardiovascular disease and chronic kidney disease (CKD). Although AGEs were originally thought to form only endogenously, primarily as the result of the hyperglycemia of diabetes, it is now clear that exogenous AGEs, specially incorporated in foods, are an important contributor to the body pool of AGEs. Over the past decade, several clinical trials have been performed in a variety of conditions demonstrating that the application of an AGE-restricted diet reduces not only the systemic levels of AGEs but also the levels of markers of oxidative stress and inflammation. This has been shown in CKD patients before and after the initiation of dialysis and either in the presence or absence of coexistent diabetes. Reduction of the AGE content in food is obtained by simple changes in culinary techniques and appears to be a feasible, easily applicable and safe intervention, even in advanced CKD patients.

Factors Associated with Albumin Loss in Post-Dilution Hemodiafiltration and Nutritional Consequences

Introduction

Hemodiafiltration is currently one of the most effective techniques of extra-renal purification but results in an increase of albumin loss in dialysate. We aimed to determine the factors associated with albumin loss during post-dilution hemodiafiltration, compare an “automatic” mode of infusate flow control versus a “manual” control, and assess the potential nutritional impact.

Methods

This prospective observational study included all hemodialysis patients in our institution who underwent post-dilution hemodiafiltration 3 times a week on a Fresenius 5008 for at least 2 months. At each session, albumin content was measured in a representative effluent dialysate volume. The automatic mode of the Fresenius 5008 was used for automatic infusate flow control.

Results

In all, 18 patients (mean age 60.7 ± 15 years) underwent 85 post-dilution hemodiafiltration sessions. The mean albumin loss was 3134 ± 2450 mg/session. Albumin loss was significantly affected by infusate flow, infusate volume, transmembrane pressure and ultrafiltration volume. The loss was greater with Toraysulfone and FX 1000 membranes rather than FX 80 or FX 100 membranes. With AutoSub rather than manual control, infusate flow was greater ( P<.001), transmembrane pressure was higher (P = .004), and the albumin loss was greater (P = .010). However, there was no correlation between albumin loss and nutritional variables.

Conclusions

Albumin loss during post-dilution hemodiafiltration was correlated with increased transmembrane pressure and infusate flow, especially AutoSub flow control, and type of membrane. However, this loss, when moderate, did not seem to affect nutritional aspects and should not limit the use of hemodiafiltration.

Glycated Serum Albumin and AGE Receptors

In vivo modification of proteins by molecules with reactive carbonyl groups leads to intermediate and advanced glycation end products (AGE). Glucose is a significant glycation reagent due to its high physiological concentration and poorly controlled diabetics show increased albumin glycation. Increased levels of glycated and AGE-modified albumin have been linked to diabetic complications, neurodegeneration, and vascular disease. This review discusses glycated albumin formation, structural consequences of albumin glycation on drug binding, removal of circulating AGE by several scavenger receptors, as well as AGE-induced proinflammatory signaling through activation of the receptor for AGE. Analytical methods for quantitative detection of protein glycation and AGE formation are compared. Finally, the use of glycated albumin as a novel clinical marker to monitor glycemic control is discussed and compared to glycated hemoglobin (HbA1c) as long-term indicator of glycemic status.

Cardiorenal syndrome type 4: a review

There is a bidirectional and complex relationship between the heart and kidneys. This interaction is physical, chemical as well as biological and is also reflected in a strong connection between renal and cardiovascular diseases. Cardiorenal syndrome type 4 (CRS type 4) is characterized by primary chronic kidney disease (CKD) leading to an impairment of cardiac function, with ventricular hypertrophy, diastolic dysfunction, and/or increased risk of adverse cardiovascular events. The incidence of CKD is increasing, and CRS type 4 is becoming a major public health problem associated with a high morbidity and mortality. In this study, we briefly review the epidemiology and pathophysiology of CRS type 4, the role of biomarkers in its early identification, and its management.

Clinical and research markers of oxidative stress in chronic kidney disease

CONTEXT

Kidney-related pathologies have increasing prevalence rates, produce a considerable financial burden, and are characterized by elevated levels of oxidative stress (OS).

OBJECTIVE

This review examines relationships between chronic kidney disease (CKD) and markers of OS and antioxidant status (AS).

METHODS

A systematic review of MEDLINE-indexed clinical trials, randomized controlled trials and comparative studies that examined OS and AS was performed.

RESULTS AND CONCLUSION

Several markers emerged as well-suited indicators of OS and AS in CKD: malondialdehyde, F2-isoprostanes, lipid hydroperoxides, asymmetric dimethylarginine, 8-oxo-7,8-dihydro-2'-deoxyguanosine, protein carbonyls, advanced oxidation protein products and glutathione-related activity.

Role of advanced glycation endproducts and potential therapeutic interventions in dialysis patients

It has been nearly 100 years since the first published report of advanced glycation end products (AGEs) by the French chemist Maillard. Since then, our understanding of AGEs in diseased states has dramatically changed. Especially in the last 25 years, AGEs have been implicated in complications related to aging, neurodegenerative diseases, diabetes, and chronic kidney disease. Although AGE formation has been well characterized by both in vitro and in vivo studies, few prospective human studies exist demonstrating the role of AGEs in patients on chronic renal replacement therapy. As the prevalence of end-stage renal disease (ESRD) in the United States rises, it is essential to identify therapeutic strategies that either delay progression to ESRD or improve morbidity and mortality in this population. This article reviews the role of AGEs, especially those of dietary origin, in ESRD patients as well as potential therapeutic anti-AGE strategies in this population.

Prognostic potential and tumor growth-inhibiting effect of plasma advanced glycation end products in non-small cell lung carcinoma

The plasma fluorescence related to the standard fluorescence of advanced glycation end products (AGEs) is a simple measurable blood parameter for distinct diseases but its importance in human cancer, including non-small cell lung carcinoma (NSCLC), is unknown. Plasma samples of 70 NSCLC patients who underwent resection surgery of the tumor were analyzed for the distinct AGE-related fluorescence at 370 nm excitation/440 nm emission. In a retrospective study, we tested the prognostic relevance of this AGE-related plasma fluorescence. The effect of circulating AGEs on the NSCLC growth was studied experimentally in vitro and in vivo. NSCLC patients with high (> median) AGE-related plasma fluorescence were characterized by a later reoccurrence of the tumor after curative surgery and a higher survival rate compared with patients with low plasma fluorescence (25% versus 47% 5-y survival, P = 0.011). Treating NSCLC cell spheroids with patients' plasma showed an inverse correlation between the growth of spheroids in vitro and the individual AGE-related fluorescence of each plasma sample. To confirm the impact of circulating AGEs on the NSCLC progression, we studied the NSCLC growth in mice whose circulating AGE level was elevated by AGE-rich diet. In vivo tumorigenicity assays demonstrated that mice with higher levels of circulating AGEs developed smaller tumors than mice with normal AGE levels. The AGE-related plasma fluorescence has prognostic relevance for NSCLC patients in whom the tumor growth-inhibiting effect of circulating AGEs might play a critical role.

Review Article: is it time to embrace haemodiafiltration for centre-based haemodialysis?

Improvements in survival in dialysis patients over the past few decades have been disappointing. Recent prospective trials such the haemodialysis study have not shown conclusive improvements. Two recent observational studies have found a striking survival advantage for haemodiafiltration (HDF). This review covers the differences between HDF and conventional haemodialysis (HD) and the history of the technological advances in the HDF technique. In addition, it explores the putative benefits of HDF over HD. While the observational studies provide a basis for optimism that HDF will provide benefit to dialysis patients, definitive conclusions cannot be drawn until the results of randomized controlled trials are available. While the evidence in favour of HDF at this stage is observational only, there are no studies suggesting that the treatment is detrimental. The use of HDF should probably be increased, particularly in centres where an increase in the frequency and duration of dialysis cannot be readily achieved.

Inflammation and oxidative stress in patients on hemodiafiltration

BACKGROUND

Chronic inflammation and oxidative stress are common features in hemodialysis patients. However, research results on the long-term influence of hemodiafiltration (HDF) on oxidative stress and inflammation are limited.

METHODS

We studied changes of inflammatory and oxidative stress biomarkers in 9 stable patients on post-dilution HDF for 9 months. Total antioxidant capacity (TAC), reactive oxygen metabolites (d-ROMs) and superoxide dismutase (SOD) measured by spectrophotometry were used as oxidative stress biomarkers. High-sensitivity CRP (hs-CRP) and IL-6 measured by ELISA were used as inflammation biomarkers.

RESULTS

d-ROMs showed significant reduction at 3 months (323.0 +/- 81.9 vs. 275.0 +/- 62.0 U, p < 0.008) and remained low (267.9 +/- 45.8 U) to the end of the study. At the end of the study there was a significant increase in TAC levels (1.3 +/- 0.1 vs. 1.4 +/- 0.1 mmol/l, p < 0.03), while SOD rise did not reach statistical significance (13.1 +/- 9.8 vs. 18.7 +/- 9.4 U/ml, p = 0.06). hs-CRP values at the end of the study decreased significantly (16.3 +/- 11.4 vs. 6.0 +/- 5.1 microg/ml, p < 0.02), while IL-6 levels showed a non-significant reduction (16.9 +/- 9.3 vs. 12.0 +/- 7.3 pg/ml, p = 0.2).

CONCLUSION

Our results suggest that post-dilution HDF for 9 months suppresses oxidative stress by rapid lowering of d-ROMs and improves antioxidant capacity by increasing TAC, while it reduces inflammation by decreasing hs-CRP.

Impaired expression and function of breast cancer resistance protein (Bcrp) in brain cortex of streptozocin-induced diabetic rats

The aim of this study was to investigate whether diabetes mellitus (DM) affected breast cancer resistance protein (Bcrp) function and expression in rat brain. 5-week and 8-week diabetic rats were induced by streptozocin (STZ). Bcrp expression and function in brain cortex were assessed by western blot and measuring the brain-to-plasma concentration ratios of two typical substrates prazosin and cimetidine, respectively. The diabetic rats were treated with three different agents insulin, aminoguanidine (AG) and metformin (MET). It was found that the brain-to-plasma ratios of prazosin and cimetidine in diabetic rats were significantly higher than those of control rats, which were dependent on duration of diabetes. Lower levels of Bcrp were found in brain cortex of diabetic rats, which were in parallel with increase of brain-to-plasma ratios. Insulin treatment may attenuate the impairment of Bcrp expression and function induced by diabetes. Aminoguanidine and metformin treatment did not prevent the impairment of Bcrp function and expression in brain cortex of diabetic rats. All results gave a conclusion that STZ-induced DM may induce the impairment of function and expression of Bcrp in brain cortex, and lower levels of insulin may mainly contribute to Bcrp dysfunction in brain.

Unchanged serum levels of advanced glycation endproducts in patients with liver disease

Advanced glycation end products (AGEs), e.g., carboxymethyllysine (CML) or imidazolone are involved in several age-related disorders. Concerning their accumulation, the importance of hepatic and renal function is controversially discussed. To test whether impairment of hepatic or renal function will affect their accumulation, both AGEs have been measured in various populations, such as 52 patients with liver disease [viral hepatitis C without (n = 19) and with (n = 10) fatty liver; nonalcoholic fatty liver (n = 13), nonalcoholic steatohepatitis (n = 10)]. Serum concentrations of both AGEs have been compared to those in 20 healthy controls and 24 patients with moderate renal impairment (creatinine clearance 23-55 ml/min). Concerning CML (95% C.I. 803-1200 ng/ml), no differences between the various groups could be observed. Likewise, serum levels of imidazolone (95% C.I. 1.3-5.6 units) were similar in all populations. In conclusion, moderate impairment in hepatic or in renal function did not affect serum levels of CML and imidazolone. Apparently, any increase observed in severe cirrhosis or renal failure seems to be rather a consequence than a cause of both disorders.

Mortality risk for patients receiving hemodiafiltration versus hemodialysis: European results from the DOPPS

Hemodiafiltration (HDF) is used sporadically for renal replacement therapy in Europe but not in the US. Characteristics and outcomes were compared for patients receiving HDF versus hemodialysis (HD) in five European countries in the Dialysis Outcomes and Practice Patterns Study. The study followed 2165 patients from 1998 to 2001, stratified into four groups: low- and high-flux HD, and low- and high-efficiency HDF. Patient characteristics including age, sex, 14 comorbid conditions, and time on dialysis were compared between each group using multivariate logistic regression. Cox proportional hazards regression assessed adjusted differences in mortality risk. Prevalence of HDF ranged from 1.8% in Spain to 20.1% in Italy. Compared to low-flux HD, patients receiving low-efficiency HDF had significantly longer average duration of end-stage renal disease (7.0 versus 4.7 years), more history of cancer (15.4 versus 8.7%), and lower phosphorus (5.3 versus 5.6 mg/dl); patients receiving high-efficiency HDF had significantly more lung disease (15.5 versus 10.2%) and received a higher single-pool Kt/V (1.44 versus 1.35). High-efficiency HDF patients had lower crude mortality rates than low-flux HD patients. After adjustment, high-efficiency HDF patients had a significant 35% lower mortality risk than those receiving low-flux HD (relative risk=0.65, P=0.01). These observational results suggest that HDF may improve patient survival independently of its higher dialysis dose. Owing to possible selection bias, the potential benefits of HDF must be tested by controlled clinical trials before recommendations can be made for clinical practice.

Haemodiafiltration, haemofiltration and haemodialysis for end-stage kidney disease

BACKGROUND

Renal replacement therapy (RRT) for end-stage kidney disease (ESKD) can be achieved by several interventions including haemodialysis (HD), peritoneal dialysis (PD) and kidney transplantation. HD, haemofiltration (HF), haemodiafiltration (HDF) and acetate-free biofiltration (AFB) are extracorporeal RRT methods. It has been suggested that HF and HDF may reduce the frequency and severity of intradialytic and post-dialytic adverse symptoms and may be more effective than HD in the removal of high molecular weight molecules.

OBJECTIVES

To compare convective modes of extracorporeal RRT (HF, HDF or AFB) with HD and to establish if any of these techniques is superior to each other in patients with ESKD.

SEARCH STRATEGY

We searched MEDLINE (1966-2006), EMBASE (1980-2006), Cochrane Central Register of Controlled Trials (CENTRAL, in The Cochrane Library issue 2, 2006) and CINAHL (1872-2006). Authors of included studies were contacted, reference lists of identified RCTs and relevant narrative reviews were screened.

SELECTION CRITERIA

RCTs comparing HF, HDF, AFB and HD for ESKD were included. Trials enrolling any patient undergoing RRT for ESKD were included.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted data. Statistical analyses were performed using the random effects model and the results expressed as relative risk (RR) for dichotomous outcomes or weighted mean difference (MD) for continuous data with 95% confidence intervals (CI). Heterogeneity was measured using the Chi-square (chi(2)) and I(2) statistic.

MAIN RESULTS

Twenty studies (657 patients) were included. Seventeen studies compared HF, HDF or AFB with HD, two compared HDF with AFB and one compared HF with HDF. The studies were generally small with suboptimal quality. Convective modalities (HF, HDF, AFB) did not differ significantly from HD for mortality (RR 1.68, 95% CI 0.23 to 12.13; chi(2)= 2.58, P = 0.11, I(2) = 61.2%), number of hospital admissions/year (MD 0.20, 95% CI -0.07 to 0.47) and dialysis adequacy (Kt/V: MD 0.09, 95% CI 0.02 to 0.17; chi(2) = 3.73, P = 0.29, I(2) = 19.6%). No study assessed number of dialysis treatments associated with "any adverse symptoms", sessions that were stopped early, change of dialysis modality or dialysis-related amyloidosis.

AUTHORS' CONCLUSIONS

We were unable to demonstrate whether convective modalities (either HF, HDF or AFB) have significant advantages over HD with regard to clinically important outcomes of mortality, dialysis-related hypotension and hospitalisation. More adequately-powered good quality RCTs assessing clinically important outcomes (mortality, hospitalisation, quality of life) are needed.

Relation between Different Treatment Modalities and Genomic Damage of End-Stage Renal Failure Patients

BACKGROUND

Patients with end-stage renal disease display enhanced genomic damage. We investigated the relation between genomic damage and different treatment modalities.

METHODS

In a longitudinal study two groups of patients were analyzed in monthly intervals. We assessed the initiation of hemodialysis in 5 conservatively treated patients, and a switch from hemodialysis to hemodiafiltration in 7 patients. DNA damage was investigated in peripheral blood lymphocytes by micronucleus frequency and by comet assay analysis. With regard to potential genotoxicity of advanced glycation end products (AGEs), levels of imidazolone A and AGE-associated fluorescence (AGE-FL) were determined.

RESULTS

The initiation of hemodialysis did not alter the genomic damage. In patients who switched from hemodialysis to hemodiafiltration, a small but significant reduction in the comet assay but not in the micronucleus frequency was observed. Elevated plasma levels of imidazolone A and AGE-FL were not influenced by the treatment modalities.

CONCLUSION

In our small patient group no major reduction of the elevated genomic damage could be reached. Disease factors not influenced by altered dialysis modalities may have contributed considerably in our patient group. The persisting high levels of DNA damage suggest a need for further improvement. Inhibiting AGE formation may be one promising way for the future.

Pigment epithelium-derived factor inhibits advanced glycation end product-induced retinal vascular hyperpermeability by blocking reactive oxygen species-mediated vascular endothelial growth factor expression

Pigment epithelium-derived factor (PEDF) is the most potent inhibitor of angiogenesis, suggesting that loss of PEDF contributes to proliferative diabetic retinopathy. However, the role of PEDF against retinal vascular hyperpermeability remains to be elucidated. We investigated here whether and how PEDF could inhibit the advanced glycation end product (AGE) signaling to vascular hyperpermeability. Intravenous administration of AGEs to normal rats not only increased retinal vascular permeability by stimulating vascular endothelial growth factor (VEGF) expression but also decreased retinal PEDF levels. Simultaneous treatments with PEDF inhibited the AGE-elicited VEGF-mediated permeability by down-regulating mRNA levels of p22(phox) and gp91(phox), membrane components of NADPH oxidase, and subsequently decreasing retinal levels of an oxidative stress marker, 8-hydroxydeoxyguanosine. PEDF also inhibited the AGE-induced vascular hyperpermeability evaluated by transendothelial electrical resistance by suppressing VEGF expression. Furthermore, PEDF decreased reactive oxygen species (ROS) generation in AGE-exposed endothelial cells by suppressing NADPH oxidase activity via down-regulation of mRNA levels of p22(PHOX) and gp91(PHOX). This led to blockade of the AGE-elicited Ras activation and NF-kappaB-dependent VEGF gene induction in endothelial cells. These results indicate that the central mechanism for PEDF inhibition of the AGE signaling to vascular permeability is by suppression of NADPH oxidase-mediated ROS generation and subsequent VEGF expression. Substitution of PEDF may offer a promising strategy for halting the development of diabetic retinopathy.

Overview of clinical studies in hemodiafiltration: what do we need now ?

Despite several technical advances in dialysis treatment modalities and a better patient care management including correction of anemia, suppression of secondary hyperparathyroidism, lipid and oxidative stress profiles improvement, the morbidity and the mortality of dialysis patients still remain still elevated. Recent prospective interventional trials in hemodialysis (HEMO study and 4D study) were not very conclusive in showing any significant improvement in dialysis patient outcomes. High-efficiency convective therapies, such as online hemodiafiltration (HDF), are claimed to be superior to conventional diffusive hemodialysis (HD) in improving the dialysis efficacy and in reducing intradialytic morbidity and all-cause and cardiovascular mortality in dialysis patients. The aim of this report was, first, to review the evidence-based facts tending to prove the superiority of HDF vs. HD in terms of efficacy and tolerance, and, second, to analyze the needs to prove the clinical superiority of HDF in terms of reducing morbidity and all-cause mortality of dialysis patients. A systematic review of studies comparing HDF and HD has been performed in the microbiological safety of online production, the solute removal capacity of small and medium-size uremic toxins, and its implication in the reduction of the bioactive dialysis system vs. patient interaction. Major planned randomized international studies comparing HDF and HD in terms of morbidity and mortality have been reviewed. To conclude, it is thought that these long-term prospective randomized trials will clarify on a scientific evidence-based level the putative beneficial role of high-efficiency HDF modalities on dialysis patient outcomes.

Serum Carboxymethyllysine Predicts Mortality in Hemodialysis Patients

BACKGROUND

Hemodialysis patients show markedly elevated serum levels of advanced glycation end products (AGEs). AGEs have been implicated in the pathogenesis of vascular damage and are regarded as a class of uremic toxins. However, to date, serum AGE level could not be identified as an independent predictor of mortality. The aim of the present study is to test whether serum level of the AGE carboxymethyllysine (CML) predicts all-cause or cardiovascular mortality in hemodialysis patients.

METHODS

Serum total CML concentration was measured by means of enzyme-linked immunosorbent assay in 154 patients receiving long-term hemodialysis. Patients were divided into groups with serum CML levels less and greater than the median (23.8 ng/mg protein). All-cause and cardiovascular mortality were registered during a follow-up of 51 months. The relationship between serum CML level and mortality was tested by using Kaplan-Meier and Cox regression analyses.

RESULTS

In the group with low serum CML levels, 38% of patients died during the follow-up period; 23% had a cardiovascular cause of death. However, in the group with high CML levels, 58% died (P < 0.01) and 36% had a cardiovascular cause of death (P < 0.05). The following parameters proved to be independent risk factors of all-cause mortality: age (hazard ratio, 1.056; P < 0.001), preexisting vascular disease (hazard ratio, 2.53; P < 0.05), smoking (hazard ratio, 3.03; P < 0.005), high serum CML level (hazard ratio, 1.776; P < 0.05), and C-reactive protein level (hazard ratio, 1.017; P < 0.001).

CONCLUSION

The AGE CML may contribute to increased mortality in patients with uremia.

A critical assessment of uremia research

There are considerably fewer randomized controlled trials investigating hemodialysis (HD) than other fields of internal medicine, and no significant improvements have been observed over time. Only the National Cooperative Dialysis Study and the HEMO trial were based on hard endpoints such as morbidity and mortality, but neither considered on-line hemodiafiltration or super-flux membranes, which are thought to provide a number of advantages in terms of the cardiovascular condition of uremic patients. However, results of well-designed clinical trials showing that increasing convection may improve the clinical outcome of HD patients are still lacking. The need for maximizing removal of uremic toxins calls for more frequent HD sessions, but this may be affected by many organizational problems. Therefore, well-designed, long-term clinical trials are urgently needed to investigate which currently available therapeutic instruments can improve the clinical outcome of uremic patients.

Ultrapure dialysate reduces plasma levels of beta2-microglobulin and pentosidine in hemodialysis patients

BACKGROUND

beta2-Microglobulin (beta2MG) and carbonyl stress are reported to contribute to the development of dialysis-related amyloidosis. The aim of this study was to determine whether the purity of dialysate affects plasma levels of beta2MG and pentosidine (a surrogate marker of carbonyl stress) in hemodialysis patients.

METHODS

Sixteen patients on hemodialysis with a polysulfone membrane participated in this study. We switched the dialysate from conventional dialysate (endotoxin level 0.055-0.066 endotoxin units (EU)/ml) to ultrapure dialysate (endotoxin level <0.001 EU/ml), followed patients for 6 months, and then switched back to conventional dialysate once again. Plasma levels of beta2MG, pentosidine, CRP and interleukin-6 (IL-6) were determined before the switch to ultrapure dialysate, 1 and 6 months after the switch to ultrapure dialysate, and 1 month after the switch back to conventional dialysate.

RESULTS

The switch from conventional to ultrapure dialysate significantly decreased plasma levels of beta2MG, from 30.1 +/- 1.4 to 27.1 +/- 1.4 mg/dl (p < 0.05) and pentosidine, from 1,535.8 +/- 107.5 to 1,267.6 +/- 102.9 nmol/l (p < 0.01) after 1 month of use. The change of dialysate also significantly decreased plasma levels of CRP, from 0.28 +/- 0.09 to 0.14 +/- 0.05 mg/dl (p < 0.05) and IL-6, from 9.4 +/- 2.7 to 3.5 +/- 0.8 pg/ml (p < 0.01) over the 1-month period. These changes in plasma levels of beta2MG, pentosidine, CRP and IL-6 were maintained over 6 months after switching to ultrapure dialysate and returned to basal levels by switching back to a conventional dialysate.

CONCLUSIONS

Ultrapure dialysate decreases plasma levels of beta2MG, pentosidine and inflammatory markers in hemodialysis patients. The use of ultrapure dialysate might be useful in preventing and/or treating complications of dialysis, such as dialysis-related amyloidosis, atherosclerosis and malnutrition.

Importance of measuring products of non-enzymatic glycation of proteins

Non-enzymatic glycation products are a complex and heterogeneous group of compounds which accumulate in plasma and tissues in diabetes and renal failure. There is emerging evidence that these compounds may play a role in the pathogenesis of chronic complications associated with diabetes and renal failure. So measurement of the products of non-enzymatic glycation has a twofold meaning: on one hand, measurement of early glycation products can estimate the extent of exposure to glucose and the subject's previous metabolic control; on the other hand, measurement of intermediate and late products of the glycation reaction is a precious instrument in verifying the relationship between glycation products and tissue modifications. This review summarizes current knowledge about the diagnostic utility of measuring non-enzymatic glycation products.

Influence of Different Haemodialysis Modalities on AGE Peptide Levels: Intradialytic versus Long-Term Results

BACKGROUND

Peptide-linked degradation products of advanced glycation end products (AGE peptides) accumulate in chronic haemodialysis (HD) patients and may contribute to a number of HD-related long-term complications, such as accelerated atherosclerosis.

METHODS

The influence of a single HD session versus long-term HD on serum AGE peptides was determined. The patients were randomized to HD with a low-flux polysulfone (PS; F 6HPS), a high-flux PS (F 60S), a superflux PS (F 500S), or a superflux cellulose triacetate (CTA; Tricea 150G) dialyzer.

RESULTS

During a single HD session, both AGE peptides and reference peptides decreased significantly (AGE peptides: Tricea 150G -37.0 +/- 2.9%; F 6HPS -35.5 +/- 2.4%; F 60S -39.5 +/- 4.7%, and F 500S -43.3 +/- 2.1%, p = 0.005; reference peptides: Tricea 150G -73.2 +/- 8.8%; F 6HPS -73.2 +/- 7.9%; F 60S -72.5 +/- 8.2%, and F 500S -74.1 +/- 7.3%, p = 0.005). After 12 weeks of HD with the superflux CTA, the AGE peptide levels decreased significantly (week 1: 2.7 +/- 1.1 arbitrary units, week 12: 2.5 +/- 1.2 arbitrary units, decrease 7.4%; p = 0.01), whereas the AGE peptide levels remained unchanged after HD with each of the other three modalities. The reference peptide levels did not change after 12 weeks of HD.

CONCLUSION

Although AGE peptides can be effectively removed during a single HD session, superflux CTA seems to be the only modality capable of reducing AGE peptides in the long term.

Paradox of circulating advanced glycation end product concentrations in patients with congestive heart failure and after heart transplantation

OBJECTIVES

To analyse circulating concentrations of advanced glycation end products (AGEs) in patients with severe congestive heart failure (CHF) and after heart transplantation; to identify the potential contribution of kidney function to plasma AGE concentrations; and to determine whether AGE concentrations and parameters of oxidative stress are interrelated.

METHODS AND RESULTS

Circulating N(epsilon)-(carboxymethyl)lysine (CML) and AGE associated fluorescence (AGE-Fl), lipid peroxidation, and glomerular filtration rate (GFR) were measured in a cross sectional study of 22 patients with advanced CHF, 30 heart transplant recipients, and 20 healthy controls. Compared with the controls, the CHF patients had decreased CML (mean (SEM) 467.8 (20.0) ng/ml v 369.3 (22.3) ng/ml, p < 0.01), AGE-Fl (mean (SEM) 302.2 (13.3) arbitrary units v 204.9 (15.7) arbitrary units, p < 0.01), and GFR (p < 0.01). CML was positively related to decreased total protein and serum albumin and negatively to body mass index (p < 0.01). In contrast, in the heart transplant group, impaired GFR was associated with a notable rise of both CML (mean (SEM) 876.1 (53.1) ng/ml, p < 0.01) and AGE-Fl (mean (SEM) 385.6 (26.1) arbitrary units, p < 0.01). A positive relation between CML and serum albumin (r = 0.394, p < 0.05) and lipofuscin (r = 0.651, p < 0.01) was found.

CONCLUSIONS

The contrasting concentration of CML and AGE-Fl between patients with CHF and after heart transplantation in the presence of decreased GFR and oxidative stress are explained by lowered plasma proteins in CHF and higher concentrations in heart transplant recipients. In heart transplant recipients, in addition to myocardial inflammatory processes, immunosuppression may be important for enhanced formation of AGEs.

The Fresenius Medical Care home hemodialysis system

The Fresenius Medical Care home dialysis system consists of a newly designed machine, a central monitoring system, a state-of-the-art reverse osmosis module, ultrapure water, and all the services associated with a successful implementation. The 2008K@home hemodialysis machine has the flexibility to accommodate the changing needs of the home hemodialysis patient and is well suited to deliver short daily or prolonged nocturnal dialysis using a broad range of dialysate flows and concentrates. The intuitive design, large graphic illustrations, and step-by-step tutorial make this equipment very user friendly. Patient safety is assured by the use of hydraulic systems with a long history of reliability, smart alarm algorithms, and advanced electronic monitoring. To further patient comfort with their safety at home, the 2008K@home is enabled to communicate with the newly designed iCare remote monitoring system. The Aquaboss Smart reverse osmosis (RO) system is compact, quiet, highly efficient, and offers an improved hygienic design. The RO module reduces water consumption by monitoring the water flow of the dialysis system and adjusting water production accordingly. The Diasafe Plus filter provides ultrapure water, known for its long-term benefits. This comprehensive approach includes planning, installation, technical and clinical support, and customer service.

Ultrapure dialysate decreases plasma pentosidine, a marker of “carbonyl stress”

BACKGROUND

Advanced glycation end products (AGEs) and their reactive carbonyl precursors accumulate in renal failure ("carbonyl stress"). Carbonyl stress derives from a broad derangement in the nonenzymatic biochemistry of both carbohydrates and lipids. We tested the influence of dialysate quality on plasma level of pentosidine, an AGE moiety taken as a surrogate marker of carbonyl stress, in hemodialysis patients.

METHODS

Plasma pentosidine is measured by means of high-performance liquid chromatography in patients hemodialyzed successively with a conventional and an ultrapure endotoxin-free dialysate.

RESULTS

Dialysate endotoxin level decreased from 0.040 +/- 0.017 EU/mL before the switch to the new water supply system to less than the detection limit (<0.001 EU/mL) after the switch. Plasma pentosidine levels decreased from 1.55 +/- 0.61 nmol/mL before the switch to 1.38 +/- 0.52 nmol/mL (P < 0.0001) and 1.31 +/- 0.50 nmol/mL (P < 0.0001) 3 and 6 months after the switch to an ultrapure dialysate, respectively. Decreases in plasma pentosidine levels were similar regardless of dialyzer membrane type; ie, high-flux polysulfone, high-flux polymethylmethacrylate, and low-flux cellulose acetate membranes. Unexpectedly, plasma triglyceride levels decreased from 150 +/- 116 mg/dL (1.69 +/- 1.31 mmol/L) before the switch to 124 +/- 79 mg/dL (1.40 +/- 0.89 mmol/L; P < 0.01) and 119 +/- 75 mg/dL (1.34 +/- 0.85 mmol/L; P < 0.01) 3 and 6 months after the switch despite unchanged total cholesterol levels, respectively. Changes in pentosidine levels were unrelated to those in triglycerides, and both were unrelated to C-reactive protein levels, which remained stable throughout the study.

CONCLUSION

Ultrapure dialysate reduces plasma pentosidine levels and improves plasma triglyceride levels in hemodialysis patients through still undefined mechanisms.

Reduction of advanced glycation end product levels by on-line hemodiafiltration in long-term hemodialysis patients

BACKGROUND

Advanced glycation end products (AGEs) are thought to be involved in many complications of end-stage renal disease. This study analyzed serum AGE level reduction rates and corresponding long-term changes in serum levels among different dialysis modes.

METHODS

Eighty-one patients with chronic uremia were divided into 3 groups receiving conventional hemodialysis (HD), high-flux HD, or on-line hemodiafiltration (HDF). Serum AGE levels were measured by competitive enzyme-linked immunosorbent assay predialysis and postdialysis and after 6 months. Additionally, AGE clearance was measured in 11 uremic patients treated with alternative high-flux HD and on-line HDF.

RESULTS

Although predialysis serum AGE levels were similar, postdialysis levels were significantly lower in patients treated with on-line HDF (35.4 +/- 4.2 microg/mL) compared with those treated with conventional HD (82.2 +/- 11.4 microg/mL; P = 0.003), but not high-flux HD (56.7 +/- 5.9 microg/mL; P = 0.15). The serum AGE level reduction rate in on-line HDF (61.5% +/- 4.2%) was significantly greater than that in conventional HD (20.5% +/- 2.4%; P < 0.001) and high-flux HD patients (40.4% +/- 2.7%; P = 0.049). AGE clearance was increased 50% with on-line HDF compared with high-flux HD, reaching borderline significance (P = 0.07). In a 6-month study, predialysis serum AGE levels were significantly lower in patients treated with on-line HDF compared with those treated with conventional and high-flux HD.

CONCLUSION

On-line HDF may provide an improved form of treatment that achieves significantly better AGE level reduction than high-flux HD and conventional HD. Uremic patients treated with on-line HDF for longer than 6 months achieved a significant reduction in predialysis serum AGE levels.

Design and technical adjustment of a water treatment system: 15 years of experience

This article gives a technical summary over the development of our dialysis water preparation site covering more than a decade of common effort to improve and secure water quality. We invite the reader to follow us through the experience of 3 major conception changes determined by available localities and resources, operational difficulties, and maintenance as well as progressive technologies and standards. Critical analysis aims to provide information to promote development in this area including details of preventable errors and misconceptions. The findings show that it is possible to achieve higher water quality on regular bases at affordable cost through technical changes, often minor; preventive maintenance; and continual monitoring of all components.