Clinical performance comparison of two medium cut-off dialyzers.

INTRODUCTION: Medium-cut-off (MCO) dialyzers may beneficially impact outcomes in patients on hemodialysis. METHODS: In a randomized, controlled trial in maintenance hemodialysis patients, the new Nipro ELISIO-17HX MCO dialyzer was compared to the Baxter Theranova 400 filter regarding middle molecule removal. Furthermore, the suitability of two assays for free lambda-light chain (λFLC) detection (Freelite vs. N-Latex) was verified. RESULTS: ELISIO-HX achieved slightly lower reduction ratios for ß2 -microglobulin (71.8 ± 6.0 vs. 75.3 ± 5.8%; p = 0.001), myoglobin (54.7 ± 8.6 vs. 64.9 ± 8.7%; p < 0.001), and kappa-FLC (62.1 ± 8.8 vs. 56.3 ± 7.7%; p = 0.021). λFLC reduction ratios were more conclusive with the Freelite assay and not different between ELISIO-HX and Theranova (28.4 ± 3.9 vs. 38.7 ± 13.4%; p = 0.069). The albumin loss of Theranova was considerably higher (2.14 ± 0.45 vs. 0.77 ± 0.25 g; p = 0.001) and the Global Removal ScoreLoss alb largely inferior (30.6 ± 7.4 vs. 82.4 ± 29.2%/g; p = 0.006) to ELISIO-HX. CONCLUSIONS: The new ELISIO-HX expands the choice of dialyzers for MCO hemodialysis.

Deep UV Formation of Long-Term Stable Optical Bragg Gratings in Epoxy Waveguides and Their Biomedical Sensing Potentials.

In this article, we summarize our investigations on optimized 248 nm deep ultraviolet (UV) fabrication of highly stable epoxy polymer Bragg grating sensors and their application for biomedical purposes. Employing m-line spectroscopy, deep UV photosensitivity of cross-linked EpoCore thin films in terms of responding refractive index change is determined to a maximum of Δn = + (1.8 ± 0.2) × 10-3. All-polymer waveguide Bragg gratings are fabricated by direct laser irradiation of lithographic EpoCore strip waveguides on compatible Topas 6017 substrates through standard +1/-1-order phase masks. According near-field simulations of realistic non-ideal phase masks provide insight into UV dose-dependent characteristics of the Bragg grating formation. By means of online monitoring, arising Bragg reflections during grating inscription via beforehand fiber-coupled waveguide samples, an optimum laser parameter set for well-detectable sensor reflection peaks in respect of peak strength, full width at half maximum and grating attenuation are derived. Promising blood analysis applications of optimized epoxy-based Bragg grating sensors are demonstrated in terms of bulk refractive index sensing of whole blood and selective surface refractive index sensing of human serum albumin.

Clinical hemocompatibility of double-filtration lipoprotein apheresis comparing polyethersulfone and ethylene-vinyl alcohol copolymer membranes.

Activation of the complement system and leukocytes by blood-membrane interactions may further promote arteriosclerosis typically present in patients on lipoprotein apheresis. As clinical data on the hemocompatibility of lipoprotein apheresis are scarce, a controlled clinical study comparing two different types of plasma separation and fractionation membranes used in double-filtration lipoprotein apheresis was urgently needed, as its outcome may influence clinical decision-making. In a prospective, randomized, crossover controlled trial, eight patients on double-filtration lipoprotein apheresis were subjected to one treatment with recent polyethersulfone (PES) plasma separation and fractionation membranes and one control treatment using a set of ethylene-vinyl alcohol copolymer (EVAL) membranes. White blood cell (WBC) and platelet (PC) counts, complement factor C5a and thrombin-antithrombin III (TAT) concentrations were determined in samples drawn at defined times from different sites of the extracorporeal blood and plasma circuit. With a nadir at 25 minutes, WBCs in EVAL decreased to 33.5 ± 10.7% of baseline compared with 63.8 ± 22.0% at 20 minutes in PES (P < .001). The maximum C5a levels in venous blood reentering the patients were measured at 30 minutes, being 30.0 ± 11.2 µg/L with EVAL and 12.3 ± 9.0 µg/L with PES (P < .05). The highest C5a concentrations were found in plasma after the plasma filters (EVAL 56.1 ± 22.0 µg/L at 15 minutes vs PES 23.3 ± 15.2 µg/L at 10 minutes; P < .001). PC did not significantly decrease over time with both membrane types, whereas TAT levels did not rise until the end of the treatment without differences between membranes. Regarding lipoprotein(a) and low-density lipoprotein (LDL) cholesterol removal, both membrane sets performed equally. Compared with EVAL, PES membranes cause less leukocyte and complement system activation, the classical parameters of hemocompatibility of extracorporeal treatment procedures, at identical treatment efficacy. Better hemocompatibility may avoid inflammation-promoting effects through blood-material interactions in patients requiring double-filtration lipoprotein apheresis.

Enhancement of solute clearance using pulsatile push-pull dialysate flow for the Quanta SC+: A novel clinic-to-home haemodialysis system.

BACKGROUND AND OBJECTIVE: The SC+ haemodialysis system developed by Quanta Dialysis Technologies is a small, easy-to-use dialysis system designed to improve patient access to self-care and home haemodialysis. A prototype variant of the standard SC+ device with a modified fluidic management system generating a pulsatile push-pull dialysate flow through the dialyser during use has been developed for evaluation. It was hypothesized that, as a consequence of the pulsatile push-pull flow through the dialyser, the boundary layers at the membrane surface would be disrupted, thereby enhancing solute transport across the membrane, modifying protein fouling and maintaining the surface area available for mass and fluid transport throughout the whole treatment, leading to solute transport (clearance) enhancement compared to normal haemodialysis (HD) operation. METHODS: The pumping action of the SC+ system was modified by altering the sequence and timings of the valves and pumps associated with the flow balancing chambers that push and pull dialysis fluid to and from the dialyser. Using this unique prototype device, solute clearance performance was assessed across a range of molecular weights in two related series of laboratory bench studies. The first measured dialysis fluid moving across the dialyser membrane using ultrasonic flowmeters to establish the validity of the approach; solute clearance was subsequently measured using fluorescently tagged dextran molecules as surrogates for uraemic toxins. The second study used human blood doped with uraemic toxins collected from the spent dialysate of dialysis patients to quantify solute transport. In both, the performance of the SC+ prototype was assessed alongside reference devices operating in HD and pre-dilution haemodiafiltration (HDF) modes. RESULTS: Initial testing with fluorescein-tagged dextran molecules (0.3 kDa, 4 kDa, 10 kDa and 20 kDa) established the validity of the experimental pulsatile push-pull operation in the SC+ system to enhance clearance and demonstrated a 10 to 15% improvement above the current HD mode used in clinic today. The magnitude of the observed enhancement compared favourably with that achieved using pre-dilution HDF with a substitution fluid flow rate of 60 mL/min (equivalent to a substitution volume of 14.4 L in a 4-hour session) with the same dialyser and marker molecules. Additional testing using human blood indicated a comparable performance to pre-dilution HDF; however, in contrast with HDF, which demonstrated a gradual decrease in solute removal, the clearance values using the pulsatile push-pull method on the SC+ system were maintained over the entire duration of treatment. Overall albumin losses were not different. CONCLUSIONS: Results obtained using an experimental pulsatile push-pull dialysis flow configuration with an aqueous blood analogue and human blood ex vivo demonstrate an enhancement of solute transport across the dialyser membrane. The level of enhancement makes this approach comparable with that achieved using pre-dilution HDF with a substitution fluid flow rate of 60 mL/min (equivalent to a substitution volume of 14.4 L in a 4-hour session). The observed enhancement of solute transport is attributed to the disruption of the boundary layers at the fluid-membrane interface which, when used with blood, minimizes protein fouling and maintains the surface area.

Differences in Dialysis Efficacy Have Limited Effects on Protein-Bound Uremic Toxins Plasma Levels over Time.

The protein-bound uremic toxins para-cresyl sulfate (pCS) and indoxyl sulfate (IS) are associated with cardiovascular disease in chronic renal failure, but the effect of different dialysis procedures on their plasma levels over time is poorly studied. The present prospective, randomized, cross-over trial tested dialysis efficacy and monitored pre-treatment pCS and IS concentrations in 15 patients on low-flux and high-flux hemodialysis and high-convective volume postdilution hemodiafiltration over six weeks each. Although hemodiafiltration achieved by far the highest toxin removal, only the mean total IS level was decreased at week three (16.6 ± 12.1 mg/L) compared to baseline (18.9 ± 13.0 mg/L, p = 0.027) and to low-flux dialysis (20.0 ± 12.7 mg/L, p = 0.021). At week six, the total IS concentration in hemodiafiltration reached the initial values again. Concentrations of free IS and free and total pCS remained unaltered. Highest beta2-microglobulin elimination in hemodiafiltration (p < 0.001) led to a persistent decrease of the plasma levels at week three and six (each p < 0.001). In contrast, absent removal in low-flux dialysis resulted in rising beta2-microglobulin concentrations (p < 0.001). In conclusion, this trial demonstrated that even large differences in instantaneous protein-bound toxin removal by current extracorporeal dialysis techniques may have only limited impact on IS and pCS plasma levels in the longer term.

Albumin Apheresis for Artificial Liver Support: In Vitro Testing of a Novel Filter.

Currently there is no direct therapy for liver failure. We have previously described selective plasma exchange therapy using a hemofilter permeable to substances that have a molecular mass of up to 100 kDa. The proof-of-concept studies and a Phase I study in patients with decompensated cirrhosis demonstrated that hemofiltration using an albumin-leaking membrane is safe and effective in removing target molecules, alleviating severe encephalopathy and improving blood chemistry. In this study a novel large-pore filter for similar clinical application is described. The performance of the filter was studied in vitro; it was found to effectively remove a wide spectrum of pathogenic factors implicated in the pathophysiology of hepatic failure, including protein bound toxins and defective forms of circulating albumin. Data on mass transport characteristics and functionality using various modes of filtration and dialysis provide rationale for clinical evaluation of the filter for artificial liver support using albumin apheresis.

Characterization of Fractionation Membranes in an Animal Model of Double Filtration Lipoprotein Apheresis.

Technical problems during clinical lipid apheresis interfere with fractionator performance. Therefore, a large animal model was established to characterize a new plasma fractionation membrane. Four sheep were randomized, controlled, and crossover subjected to double ofiltration lipoprotein apheresis with three specimens of FractioPESR having slightly different HDL sieving coefficients (SK ) (FPESa, 0.30, FPESb, 0.26, and FPESc, 0.22) versus a control fractionator (EVAL). SK and reduction ratios were determined for LDL, HDL, fibrinogen, IgG, and albumin. Compared to EVAL (0.42 ± 0.04 to 0.74 ± 0.08) and FPESa (0.36 ± 0.06 to 0.64 ± 0.04), SK for HDL were lower (P < 0.05) with FPESc (0.30 ± 0.04 to 0.49 ± 0.10). Fibrinogen SK were higher (P < 0.05) with EVAL (0.02 ± 0.01 to 0.40 ± 0.08) compared to FPESb (0.05 ± 0.02 to 0.26 ± 0.34) and FPESc (0.01 ± 0.01 to 0.21 ± 0.16). No further differences were determined. The animal model distinguished between minor differences in fractionation membrane permeability, demonstrating equivalent sieving of FPESa and EVAL and slightly inferior permeability of FPESb and FPESc.

Influence of nanoporous poly(ether imide) particle extracts on human aortic endothelial cells (HAECs).

Accumulated uremic toxins like indoxyl sulphate, hippuric acid and p-cresyl sulphates in renal failure patients stimulate proinflammatory effects, and consequently kidney and cardiovascular diseases. Low clearance rate of these uremic toxins from the blood of uremic patients by conventional techniques like hemodialysis is due to their strong covalent albumin binding (greater than 95%) and hydrophobic nature, which led to alternatives like usage of hydrophobic adsorber's in removing these toxins from the plasma of kidney patients. Polymers like polyethylene, polyurethane, polymethylmethacrylate, cellophane and polytetrafluoroethylene were already in use as substitutes for metal devices as dialysis membranes. Among new synthetic polymers, one such ideal adsorber material are highly porous microparticles of poly(ether imide) (PEI) with diameters in the range from 50-180µm and a porosity around 88±2% prepared by a spraying and coagulation process.It is essential to make sure that these synthetic polymers should not evoke any inflammatory or apoptotic response during dialysis. Therefore in our study we evaluated in vitro effect of PEI microparticle extracts in human aortic endothelial cells (HEACs) concerning toxicity, inflammation and apoptosis. No cell toxicity was observed when HAECs were treated with PEI extracts and inflammatory/apoptotic markers were not upregulated in presence of PEI extracts. Our results ensure biocompatibility of PEI particles and further hemocompatibility of particles will be tested.

Effect of extracts of poly(ether imide) microparticles on cytotoxicity, ROS generation and proinflammatory effects on human monocytic (THP-1) cells.

Current haemodialysis techniques are not capable to remove efficiently low molecular weight hydrophobic uremic toxins from the blood of patients suffering from chronic renal failure. With respect to the hydrophobic characteristics and the high level of protein binding of these uremic toxins, hydrophobic adsorber materials might be an alternative to remove these substances from the plasma of the chronic kidney disease (CKD) patients. Here nanoporous microparticles prepared from poly(ether imide) (PEI) with an average diameter of 90 ± 30 µm and a porosity around 88 ± 2% prepared by a spraying/coagulation process are considered as candidate adsorber materials. A prerequisite for the clinical application of such particles is their biocompatibility, which can be examined i.e. indirectly in cell culture experiments with the particles' extracts. In this work we studied the effects of aqueous extracts of PEI microparticles on the viability of THP-1 cells, a human leukemia monocytic cell line, as well as their macrophage differentiation, reactive oxygen species (ROS) generation and inflammation.A high cell viability of around 99 ± 18% and 99 ± 5% was observed when THP-1 cells were cultured in the presence of aqueous extracts of the PEI microparticles in medium A and medium B respectively. The obtained microscopic data suggested that PEI particle extracts have no significant effect on cell death, oxidative stress or differentiation to macrophages. It was further found that the investigated proinflammatory markers in THP-1 cells were not up-regulated. These results are promising with regard to the biocompatibility of PEI microparticles and in a next step the hemocompatibility of the microparticles will be examined.

Pharmacokinetics of Certoparin During In Vitro and In Vivo Dialysis.

The efficacy and safety of certoparin in the prophylaxis of clotting during hemodialysis have recently been proven. Different to other low-molecular weight heparins (LMWHs), certoparin does not accumulate in maintenance dialysis patients for unknown reasons. The purpose of the present study was to examine the impact of the dialysis procedure on the removal of certoparin. In a subgroup of the MEMBRANE study consisting of 12 patients, the pharmacokinetics of certoparin during hemodialysis was determined by means of the anti-Xa activity. In addition, the elimination of certoparin into continuously collected dialysate was assessed. Further, in vitro experiments with human blood-simulating high-flux hemodialysis and hemofiltration were performed to quantify the elimination and the sieving coefficients SK of the two LMWHs certoparin and enoxaparin compared with unfractionated heparin (UFH). The surrogate marker middle molecules inulin and myoglobin served as reference solutes during the experiments. Finally, the adsorption of (125) iodine-radiolabeled certoparin onto the synthetic dialysis membrane was quantified. The clinical study reconfirmed the absence of bioaccumulation of certoparin with anti-Xa activities between <0.01 and 0.02 IU/mL after 24 h. A short plasma half-life time of 2.0 ± 0.7 h was determined during hemodialysis. Of the total certoparin dose injected intravenously prior to hemodialysis, only 2.7% was eliminated into dialysate. The in vitro experiments further revealed only 6% of certoparin to be adsorbed onto the dialysis membrane. The anti-Xa activities of certoparin and enoxaparin slowly declined during in vitro hemofiltration to 87.3 ± 5.5 and 82.5 ± 9.4% of baseline, respectively, while inulin and myoglobin concentrations rapidly decreased. The anti-Xa activity of UFH remained unchanged. The SK of both LMWH and UFH was very low in hemofiltration and particularly in hemodialysis with values ≤0.1. The elimination kinetics during hemodialysis suggests strong protein-binding of certoparin. Different from LMWH significantly cleared by the kidneys, the relatively short half-life time of certoparin of only 2 h during hemodialysis allows a more reliable control of the anti-coagulatory effects and decreases the risk of bleeding complications. Dialytic removal does not significantly contribute to the clearance of certoparin in maintenance dialysis patients.

Uremic toxicity and sclerostin in chronic kidney disease patients.

BACKGROUND AND AIMS: Sclerostin is a circulating inhibitor of the Wnt/ß-catenin pathway and may have a role in chronic kidney disease (CKD)-mineral and bone disorder. Blood sclerostin levels are known to be elevated in patients undergoing maintenance dialysis. The aims of the present study were to evaluate sclerostin levels in patients at different CKD stages and study potential associations between sclerostin levels and (i) biochemical parameters that are disturbed in CKD, (ii) markers of vascular disease and (iii) mortality. METHODS: One hundred and forty patients at CKD stages 2-5D were included in the present study. Routine clinical biochemistry tests and assays for sclerostin, protein-bound uremic toxins (indoxylsulphate [IS] and p-cresyl sulphate [PCS]) and the toxin ß2 microglobulin (ß2M) were performed. Aortic and coronary calcification and arterial stiffness were assessed by multislice spiral computed tomography and pulse wave velocity measurements. The enrolled patients were prospectively monitored for mortality. RESULTS: Sclerostin levels were found to be elevated in CKD patients (especially those on hemodialysis). Furthermore, sclerostin levels were positively correlated with inflammation markers, phosphate, fibroblast growth factor 23, IS, PCS, ß2M and arterial stiffness. A multivariate linear regression analysis indicated that sclerostin levels were independently associated with IS, PCS and ß2M levels. Elevated serum sclerostin appeared to be associated with mortality (independently of age and inflammation). However, this association disappeared after adjustment for a propensity score including age, phosphate, interleukin-6, CKD stage and PCS. CONCLUSION: Our results indicate that sclerostin levels are elevated in CKD patients and are associated with inflammation, vascular lesions, uremia and (potentially) mortality.

Binding affinity and capacity for the uremic toxin indoxyl sulfate.

Protein binding prevents uremic toxins from removal by conventional extracorporeal therapies leading to accumulation in maintenance dialysis patients. Weakening of the protein binding may enhance the dialytic elimination of these toxins. In ultrafiltration and equilibrium dialysis experiments, different measures to modify the plasma binding affinity and capacity were tested: (i), increasing the sodium chloride (NaCl) concentration to achieve a higher ionic strength; (ii), increasing the temperature; and (iii), dilution. The effects on the dissociation constant K(D) and the protein bound fraction of the prototypical uremic toxin indoxyl sulfate (IS) in plasma of healthy and uremic individuals were studied. Binding of IS corresponded to one site binding in normal plasma. K(D) increased linearly with the NaCl concentration between 0.15 (K(D) = 13.2 ± 3.7 µM) and 0.75 M (K(D) = 56.2 ± 2.0 µM). Plasma dilution further reduced the protein bound toxin fraction by lowering the protein binding capacity of the plasma. Higher temperatures also decreased the protein bound fraction of IS in human plasma. Increasing the NaCl concentration was effective to weaken the binding of IS also in uremic plasma: the protein bound fraction decreased from 89% ± 3% to 81% ± 3% at 0.15 and 0.75 M NaCl, respectively. Dilution and increasing the ionic strength and temperature enhance the free fraction of IS allowing better removal of the substance during dialysis. Applied during clinical dialysis, this may have beneficial effects on the long-term outcome of maintenance dialysis patients.

Clearance of drugs for multiple myeloma therapy during in vitro high-cutoff hemodialysis.

Current chemotherapy for multiple myeloma is based on bortezomib (BOR), dexamethasone (DEX), and thalidomide (THA). The purpose of the present study was to examine their clearance during high-cutoff (HCO) hemodialysis and to accordingly apply the results to the dialytic removal of protein-bound substances in general. During in vitro hemodialysis with human blood (blood, dialysate, and ultrafiltration flow rates 250, 500 and 5 mL/min, respectively) comparing a highly permeable HCO dialyzer (Theralite, 2.1 m(2) ) to a high-flux dialyzer (PFX; 2.1 m(2) ), ultrafiltered volume was replaced by saline containing 30 g/L urea. After recirculation for equilibration, BOR was injected, and arterial and venous samples were drawn after 10, 11, and 12 min to measure the plasma clearance (K) of both urea and BOR. The same procedure was performed with THA and DEX. By mathematical simulation, the influence of varying plasma albumin concentrations (CHSA ) on the protein-bound drug fraction (PBF) and K was assessed. Plasma K values of HCO and PFX for THA, BOR, and DEX were about 40% (80 ± 7 vs. 65 ± 6 mL/min; P < 0.05), 70% (40 ± 8 vs. 33 ± 4 mL/min; P < 0.05), and 65% (47 ± 11 vs. 38 ± 7 mL/min; P < 0.05), respectively-lower (P < 0.0001) compared with urea (125 ± 7 vs. 122 ± 5 mL/min). K was highest (P < 0.0001) for THA. K was negatively correlated with CHSA (THA, r(2) = 0.58, P < 0.001; BOR, r(2) = 0.24, P < 0.05; DEX, r(2) = 0.22, P < 0.05). CHSA continually decreased (P < 0.05) over time only with HCO, resulting in lower calculated PBF. Compared with BOR and DEX (minimum 72 and 56%, respectively), the PBF of THA (37%) was significantly lower (P < 0.001). A mathematical simulation based on the K values of urea and the drugs reliably estimated PBF (r(2) = 0.886, P < 0.001). Drugs for multiple myeloma therapy are significantly removed with both HCO and PFX, with important implications for the dosing and timing of administration, particularly in patients with cast nephropathy receiving extended dialysis. If the Kurea of a dialyzer and the PBF of any given drug are known, Kdrug can be reliably estimated by mathematical simulation.

Association between free light chain levels, and disease progression and mortality in chronic kidney disease.

Immunoglobulin free light chains (FLCs) form part of the middle molecule group of uremic toxins. Accumulation of FLCs has been observed in patients with chronic kidney disease (CKD). The aim of the present study was to measure FLC levels in patients at different CKD stages and to assess putative associations between FLC levels on one hand and biochemical/clinical parameters and mortality on the other. One hundred and forty patients at CKD stages 2-5D were included in the present study. Routine clinical biochemistry assays and assays for FLC kappa (κ) and lambda (λ) and other uremic toxins were performed. Vascular calcification was evaluated using radiological techniques. The enrolled patients were prospectively monitored for mortality. Free light chain κ and λ levels were found to be elevated in CKD patients (especially in those on hemodialysis). Furthermore, FLC κ and λ levels were positively correlated with inflammation, aortic calcification and the levels of various uremic toxins levels. A multivariate linear regression analysis indicated that FLC κ and λ levels were independently associated with CKD stages and ß2 microglobulin levels. Elevated FLC κ and λ levels appeared to be associated with mortality. However, this association disappeared after adjustment for a propensity score including age, CKD stage and aortic calcification. In conclusion, our results indicate that FLC κ and λ levels are elevated in CKD patients and are associated with inflammation, vascular calcification and levels of other uremic toxins. The observed link between elevated FLC levels and mortality appears to depend on other well-known factors.

The "artificial artery" as in vitro perfusion model.

Metabolic stimuli, pressure, and fluid shear stress (FSS) are major mediators of vascular plasticity. The exposure of the vessel wall to increased laminar FSS is the main trigger of arteriogenesis, the remodelling of pre-existent arterio-arteriolar anastomoses to functional conductance arteries. In this study, we have used an in vitro bioreactor to investigate cell-specific interactions, molecular mechanisms as well as time-dependent effects under laminar FSS conditions. This bioreactor termed "artificial artery" can be used for screening potential arterio-protective substances, pro-arteriogenic factors, and for investigating biomarkers of cardiovascular diseases such as cardiac diseases. The bioreactor is built up out of 14 hollow fiber membranes colonized with endothelial cells (HUVECs) on the inside and smooth muscle cells (HUASMCs) on the outside. By means of Hoechst 33342 staining as well as immunocytochemistry of ß-catenin and α-smooth-muscle-actin, a microporous polypropylene membrane was characterized as being the appropriate polymer for co-colonization. Defined arterial flow conditions (0.1 N/m2 and 3 N/m2), metabolic exchange, and cross-talk of HUVECs and HUASMCs through hollow fibers mimic physiological in vivo conditions of the vasculature. Analysing mono- and co-culture secretomes by MALDI-TOF-TOF mass spectrometry, we could show that HUVECs secreted Up4A upon 3 N/m2. A constant cellular secretion of randomly chosen peptides verified viability of the "artificial artery" for a cultivation period up to five days. qRT-PCR analyses revealed an up-regulation of KLF2 and TIMP1 as mechano-regulated genes and demonstrated arterio-protective, homeostatic FSS conditions by a down-regulation of EDN1. Expression analyses of VWF and EDN1 furthermore confirmed that RNA of both cell types could separately be isolated without cross-contamination. CCND1 mRNA expression in HUVECs did not change upon FSS indicating a quiescent endothelial phenotype. Taken together, the "artificial artery" provides a solid in vitro model to test pharmacological active compounds for their impact on arterio-damaging or arterio-protective properties on vascular response.

Bisphenol A in chronic kidney disease.

The estrogenic endocrine-disrupting substance bisphenol A (BPA) is extensively used as a starting material for a variety of consumer plastic products including dialyzer materials. The present study was performed to explore plasma BPA levels in patients with impaired renal function and to investigate if dialyzers differing in elutable BPA influence plasma levels in patients on maintenance hemodialysis. In vitro BPA was eluted from high-flux polyethersulfone (PUREMA H, referred as PUR-H), high-flux polysulfone (referred as HF-PSu), and low-flux polysulfone (referred as LF-PSu) dialyzers by recirculation with water for 180 min. In a cross-sectional clinical study, plasma BPA levels of outpatients with different stages of chronic kidney disease (CKD) from four different centers were determined. Furthermore, in a prospective, randomized, and crossover setting, 18 maintenance dialysis patients were subjected successively to 4 weeks of thrice-weekly hemodialysis with each LF-PSu, HF-PSu, and PUR-H. In addition, the fractions of protein-bound and free BPA were determined in a subset of dialysis patients. The mass of BPA eluted from the blood compartments in vitro under aqueous conditions varied for the three dialyzers being very low for PUR-H (6.2 ± 2.5 ng; P < 0.001), intermediate for HF-PSu (48.1 ± 7.7 ng), and highest for LF-PSu (140.8 ± 38.7 ng; P < 0.01). In 152 prevalent patients with CKD enrolled in the cross-sectional trial, plasma BPA started to rise after stage 3. Maintenance hemodialysis patients had more than six times higher BPA concentrations than patients with CKD stage 5 not yet on dialysis (10.0 ± 6.6 vs. 1.6 ± 1.8 ng/mL; P < 0.001). The BPA concentrations highly and inversely correlated with renal function. In the randomized controlled study, the plasma BPA concentrations were highly elevated compared with healthy controls (range 9.1 ± 4.5-12.0 ± 6.0 ng/mL vs. ≤0.2 ± 0.1 ng/mL; P < 0.001), but no change of the plasma levels was observed during hemodialysis with any of the three dialyzers in the course of a single treatment and over a period of 4 weeks. The protein-bound fraction of plasma BPA in the dialysis patients was 74 ± 5%. Renal function and, most likely, the total quantity of ingested BPA are essential parameters affecting plasma BPA concentrations. Dialyzers are one additional source of BPA, but differences in the elutable BPA content are not associated with a significant effect on BPA plasma levels in Western European maintenance dialysis patients. Due to high protein binding, the removal of BPA by hemodialysis is limited.

The clinical impact of plasma leptin levels in a cohort of chronic kidney disease patients.

BACKGROUND: Recent research has clarified the relationship between adipokines, metabolic syndrome (MS) and cardiovascular disease (CVD). The results of animal and clinical studies have revealed a positive relationship between leptin and vascular smooth muscle cell counts and calcification, arterial rigidity, carotid thickness and the incidence of CVD. However, despite leptin fulfilling the definition of a uremic toxin, its exact role in chronic kidney disease (CKD) has yet to be determined. METHODS: One hundred and forty-two CKD patients (stages 2-5D) participated in this study, and were followed for a minimum of 20 months at Amiens University Medical Center. RESULTS: Leptin was negatively correlated with the glomerular filtration rate (GFR), total adiponectin (TAdip) and high-molecular weight adiponectin and positively correlated with age, waist circumference, body mass index (BMI), aortic calcification score (ACS), C-reactive protein (CRP), triglycerides, insulin and parathormone (PTH). Leptin and insulin were significantly correlated with the MS score. The BMI, insulin, MS score and PTH were independent predictors of leptin levels (P = 0.002, 0.016, 0.028 and 0.017, respectively). Leptin, insulin and TAdip were independent predictors of the presence of MS (P = 0.05, 0.04 and 0.04). However, leptin levels were not significantly predictive of the clinical outcomes. CONCLUSIONS: Our study was the first to demonstrate a significant, independent link between leptin and MS (but not clinical outcomes) and PTH in patients at different CKD stages. Future studies will have to assess the involvement of leptin in MS and clinical outcomes in CKD, and the potential modulation of leptin by PTH.

Prognostic implications of plasma myoglobin levels in patients with chronic kidney disease.

PURPOSE: Poor cardiovascular outcomes in chronic kidney disease (CKD) patients have prompted nephrologists to look for biomarkers that may improve risk stratification in this population. The objective of this study was to evaluate plasma myoglobin (Mb) levels according to the CKD stage and to determine whether they are associated with overall, cardiovascular (CV) mortality, CV events, and renal outcomes. METHODS: Plasma Mb levels were determined in 140 CKD patients at different stage (mean ± SD age: 67 ± 12; males: 61%) who were prospectively monitored for overall and CV mortality, CV events and CKD progression. Twenty-seven healthy subjects served as controls. RESULTS: Plasma Mb levels were higher in CKD patients than in controls and progressively increased as the glomerular filtration rate fell. Hemoglobin levels, CKD stage, the aortic calcification score and brain natriuretic peptide levels were associated with plasma Mb concentrations. In a multivariate analysis, only CKD stage was associated with Mb levels. During follow up (mean duration: 968 ± 374 days), 44 patients died and 63 had a cardiovascular event. In a crude analysis, plasma Mb >73.8 µg/l predicted overall and cardiovascular mortality and the occurrence of cardiovascular events (p = 0.01, 0.05 and 0.01, respectively). However, this association was lost after adjustment for other prognostic factors for mortality. Plasma Mb was not a significant predictor of the progression of CKD either. CONCLUSIONS: Plasma Mb levels were significantly higher in predialysis or dialyzed CKD patients than in healthy controls. However, we could not identify a relevant clinical outcome associated with this elevation. Larger studies are needed to confirm the present results.

Plasma beta-2 microglobulin is associated with cardiovascular disease in uremic patients.

Since beta-2 microglobulin (B2M) is a surrogate marker for middle molecular weight uremic toxins and the major protein component in dialysis-related amyloidosis, it has been frequently studied in dialysis patients. It is not known, however, whether B2M has an impact in patients with chronic kidney disease (CKD) not yet on dialysis. Here we studied the relationship of plasma B2M levels to clinical and cardiovascular outcomes in 142 patients (mean age of 67 years) at different stages of CKD. B2M levels increased with CKD stage and thus were highest in hemodialysis patients. Baseline B2M levels were associated with vascular calcification but not with arterial stiffness or bone density. During a mean follow-up of 969 days, 44 patients died and 49 suffered a cardiovascular event. Higher B2M levels were independently associated with overall and cardiovascular mortality and cardiovascular events in the whole cohort and with cardiovascular events in the predialysis cohort. Moreover, B2M appeared to be a better predictor than well-established factors associated with outcomes in this population, such as estimated glomerular filtration rate ((eGFR), only for predialysis patients), inflammation biomarkers, and other factors included in a propensity score. Thus, we confirm the strong relationship between B2M levels and eGFR and confirm the power of B2M to predict overall and cardiovascular mortality and cardiovascular events in patients at different stages of CKD.

A multi-center, prospective, open-label, 8-week study of certoparin for anticoagulation during maintenance hemodialysis--the membrane study.

BACKGROUND: Adequate anticoagulation is prerequisite for effective hemodialysis to prevent clotting in the extracorporeal circuit. We aimed providing first data on the efficacy and safety of the low-molecular-weight heparin certoparin in this setting. METHODS: Multicenter, open-label, 8-week trial. Patients received a single dose of 3,000 IU certoparin i.v. with additional titration steps of 600 IU and/or continuous infusion if necessary. RESULTS: 120 patients were screened, 109 enrolled (median age 71; range 26-90 years) and 106 available for efficacy analyses. The percentage of unsatisfactory dialysis results at 8 weeks due to clotting or bleeding, was 1.9% (n = 2/106; 95% confidence interval [CI] 0.23-6.65%); no major bleeding. 1.9% had moderate/severe clotting in the lines/bubble catcher and 2.8% in the dialyser at week 8. 15.7 ± 14.3% of the dialysis filters' visual surface area was showing redness. In subgroups of patients receiving median doses of 3000 ± 0, 3000 (2400-6000) and 4200 (3000-6600) IU, plasma aXa levels at baseline, 4 and 8 weeks were 0.24 [95%CI 0.21-0.27], 0.33 [0.27-0.40] and 0.38 [0.33-0.45] aXa IU/ml at 2 h. C48h was 0.01 [0.01-0.02] aXa IU at all visits. At baseline and 4 weeks AUC0-48h was 2.66 [2.19-3.24] and 3.66 [3.00-4.45] aXa IU*h/ml. In 3.0% of dialyses (n = 83/2724) prolonged fistula compression times were documented. Eight patients (7.34%) had at least one episode of minor bleeding. 4) 85.3% of patients had any adverse event, 9.2% were serious without suspected drug relation; and in 32 patients a drug-relation was suspected. CONCLUSIONS: Certoparin appears effective and safe for anticoagulation in patients undergoing maintenance hemodialysis.