Cellulose Triacetate Membrane Research Articles

Blood Compatibility and Filtration: Characteristics of Newly Developed Polyester Polymer Alloy Membrane

Many synthetic polymeric membranes have been widely used for blood purification therapies. Among them polyester polymer alloy (PEPA) membrane shows unique blood compatibility and filtration characteristics.Objective: To evaluate blood compatibility and filtration characteristics of 3 different PEPA membranes, including FLX (PEPA only), FDX (PEPA with polyvinylpyrrolidone, (PVP) as a hydrophilic agent), and FDY (PEPA with PVP) that has larger pore diameter.Methods: Ultrafilters with 3 PEPA membranes (FLX, FDX, FDY, Nikkiso, Tokyo) were compared with those with polysulfone (PS; NK‐PS, Nikkiso, Tokyo) for blood compatibility in vivo. Also, ultrafilters with PEPA, PS, and cellulose triacetate (CTA; FB‐110GA, Nipro, Osaka) membranes were also investigated for filtration characteristics of albumin in aqueous in vitro.Results: FDY, the latest version of the three PEPA, showed excellent small changes in C5a concentration during the treatment right after switching from PS membrane, leaving no significant changes in other biocompatible indices. First 60 min of the time course of s.c. for albumin were shown below taken under aqueous low albumin concentration, i.e., 2.42 × 10−3 kg/dm3. The time‐dependent patterns were totally different from each other in 5 filters. Generally speaking, PS takes a peak value 20–40 min after starting the experiment, depending on the flow conditions. Since PEPA is a hydrophobic material, it showed high s.c. for albumin in FLX (PEPA with no PVP) and never reached plateau. With a hydrophilic agent (PVP), the s.c. greatly reduced in FDX and showed little time‐dependent change. By enlarging the pore diameter in FDY, the s.c. increased in accordance with the enlargement.Conclusion: Newly developed PEPA with PVP has excellent blood compatibility and has unique separation characteristics for albumin.

Management of Refractory Ascites by Using a Peritoneal Dialysis System with Extracorporeal Ultrafiltration by Hemodialysis Dialyzer

The treatment of refractory ascites remains a challenge in cirrhosis with ascites and end-stage renal disease (ESRD). Successful experiences with continuous ambulatory peritoneal dialysis (CAPD) for treatment of ESRD patients with ascites secondary to liver cirrhosis have been reported, but the CAPD modality has the drawback of protein loss and was observed to cause patients to become severely malnourished. We devised a CAPD method for treatment of ascites without protein loss. We use a peritoneal dialysis (PD) system to drain ascitic fluid and to reinject concentrated ascites into the abdomen after extracorporeal ultrafiltration of the ascitic fluid using a hemodialysis dialyzer and pump. Here, we report our experience with 2 cirrhotic patients with ascites treated by this method. Ascites are collected by gravity through a Y transfer set into a 3-L plastic bag for intravenous hyperalimentation. The ascitic fluid drained is removed by a pump at a rate of 200 mL/min (AK-90: Gambro Lundia, Lund, Sweden) and passed through a hollow-fiber dialyzer with triacetate membrane (FB-210G: Nipro, Osaka, Japan). Heparin (5,000 U) is infused into the inflow line at the start of the session only. At the end of treatment, about 500 mL concentrated ascitic fluid is returned to the peritoneal cavity by gravity through the Y transfer set. Case 1: A 77-year-old female was referred to us because of massive ascites from hepatic cirrhosis associated with hepatitis B infection and renal insufficiency. Abdominal paracentesis was required once weekly for recurrence of massive ascites. As a result, the patient was obliged to stay in the bed almost all day, and her nutritional condition deteriorated because of poor appetite and respiratory compromise. Using the Y transfer set, we commenced using our method, and performed it thrice or twice weekly. After 9 months of treatment, the patient's body weight was being maintained at 52 kg, and her serum albumin level had risen from 2.4 g/dL to 3.4 g/dL without albumin administration. Case 2: A 61-year-old male with diabetes from the age of 51 was diagnosed with hepatitis C at age 53. At age 60, his renal function deteriorated, requiring hemodialysis (HD). After 3 months, abdominal distention was noted, and HD was frequently complicated by low blood pressure, large weight gains between HD treatments, and interruption of HD sessions. Albumin administration was required to treat the low blood pressure. Ascites was poorly controlled using HD, and tense ascites developed, requiring repeated paracentesis for comfort. At first during application of our method, ascitic fluid volume was 6 L per thrice-weekly HD session. After 5 months, ascitic fluid volume had diminished to about 2 - 3 L per HD session, and we decreased the frequency of our method to once weekly. Protein levels in the ascitic fluid were 6 g/dL at the start of treatment and decreased to 2 - 3 g/dL after 6 months. Hemodynamic instability during HD was reduced. We conclude that management of refractory ascites by using a PD system with extracorporeal ultrafiltration by an HD dialyzer is useful. The technique compensates for the drawbacks of PD management of ESRD patients with ascites, although further experience with the technique is necessary.

Fixed sites plasticized cellulose triacetate membranes containing crown ethers for silver(I), copper(II) and gold(III) ions transport

New cellulose triacetate membranes (CTA) containing the macrocyclic polyethers dibenzo-18-crown-6 (DB18C6), hexathia-18-crown-6 (HT18C6), diaza-18-crown-6 (DA18C6) and hexaaza-18-crown-6 (HA18C6) as fixed carriers were prepared, characterized and applied for facilitated transport of copper(II), silver(I) and gold(III) metal cations. FTIR, X-ray, SEM and TGA analyses showed that the polyethers crystallize inside the membrane and no new chemical bonds have been formed. A comparative study of the transport parameters across such fixed sites membranes (FSM) and supported liquid membranes (SLM) containing the same carriers has been made. The mass fluxes obtained with FSM are higher than that obtained with SLM when increasing the carrier concentration. However, beyond 1.13×10 −3 g of carrier/cm 2 of membrane, the mass flux of all three ions through the FSM reaches a value almost zero due to the formation of multilayers of carrier or aggregates onto the membrane matrix which was revealed by SEM observations of FSM-cross sections. The stability of the membrane was constant over 15 days.

Caspase-3 and -8 activation and cytokine removal with a novel cellulose triacetate super-permeable membrane in an in vitro sepsis model.

Pro-apoptotic molecules are generated during sepsis which may be responsible for alteration of organ function in sepsis. Removal of systemic apoptotic activity may affect recovery from sepsis. Current high flux membranes might not be sufficiently permeable to eliminate pro-apoptotic factors. We evaluated the elimination of pro-apoptotic factors induced by LPS in human whole blood by a super-permeable cellulose triacetate membrane (SUREFLUX FH 150, Nipro, Osaka, Japan) in comparison to a standard high flux cellulose triacetate membrane (UT 700, Nipro, Osaka, Japan) and a polyethersulfone plasmafilter (Bellco, Mirandola Italy) in an in vitro blood circulation. We spiked human whole blood with lipopolysaccharide from Escherichia coli (Serotype 026-86, 10 mg/ml), incubated it for 3 hours to allow cytokine generation and recirculated it at 300 ml/min for 3 hours. The UF line was first returned to the blood module at 10 min. After this, the UF was drained from 10 to 60 min at a rate of 1000 ml/h. Zero balance was obtained by re-infusion of bicarbonate buffered hemofiltration fluid. Apoptosis was assessed on U937 monocytes (incubated with plasma or ultrafiltrate) by fluorescence microscopy dyes (Hoechst 33342, propidium iodide) and annexin V flow cytometry. Caspase-3 and Caspase-8 activity was assessed on the recirculated blood monocytes by spectrophotometric methods. IL-2, IL-10 and TNFalpha were determined by commercially available ELISAs. Sieving coefficients and clearances were determined for the different cytokines. Caspase-3 and Caspase-8 were activated by LPS and remained either stable or increased during in vitro circulation. Apoptosis activity of U937 cells, when incubated with the ultrafiltrate, increased in parallel with arterial plasma values (for Uf: UT700 = 23.1%; Sureflux FH150 = 42.5%). However, by 60 min the apoptotic activity recorded with the ultrafiltrate was reduced to the levels of arterial plasma (for Uf: UT700 = 19.8%; Sureflux FH150 = 11.2%). Sieving coefficients in the super-permeable membrane were significantly higher for all measured cytokines in comparison to the standard high flux membrane (e.g. TNFalpha 0.72 vs 0.03 p < 0.001) and close to the values observed for the plasmafiltration membrane. Nevertheless protein losses measured by albumin leakage were much lower with the Sureflux filter in comparison to the plasmafilter. In conclusion, pro-apoptotic factors can be eliminated by dialytic membranes with the removal rate maximized by using super high flux dialysers which may represent a compromise between hemofiltration and plasmafiltration membranes.

Importance of asymmetric structure in determining mass transport characteristics of hollow fiber hemodialyzers

Most synthetic hemodialysis membranes have an asymmetric structure consisting of a thin semi-permeable skin and a more open support structure. The impact of this asymmetric structure on the transport characteristics of hemodialysis membranes has not been appreciated. Experimental data were obtained for solute clearance and sieving through asymmetric polysulfone membranes and homogeneous cellulose triacetate hollow fiber membranes. The clearance of urea and the large molecular weight dextrans were greater for the cellulose triacetate membrane compared to the polysulfone, but the clearance of the smaller molecular weight dextrans was slightly greater for the polysulfone dialyzer. The sieving coefficients for the asymmetric membrane were uniformly smaller than those for the homogeneous membrane, although this effect was dramatically reduced at very small filtration velocities. These results were in good agreement with theoretical calculations based on a two-layer model for the asymmetric membrane and available hydrodynamic descriptions of hindered solute transport.

Effects of high-flux hemodialysis on oxidant stress

Neutrophil oxygen radical production is increased in end-stage renal disease (ESRD) patients and it is further enhanced during dialysis with low-flux cellulosic membranes. This increased oxygen radical production may contribute to the protein and lipid oxidation observed in ESRD patients. We tested the hypothesis that high-flux hemodialysis does not increase oxygen radical production and that it is not associated with protein oxidation. Neutrophil oxygen radical production was measured during dialysis with high-flux dialyzers containing polysulfone and cellulose triacetate membranes. Free sulfhydryl and carbonyl groups and advanced oxidation protein products were measured to assess plasma protein oxidation. Pre-dialysis, neutrophil oxygen radical production was significantly greater than normal and increased significantly as blood passed through the dialyzer in the first 30 minutes of dialysis. Post-dialysis, however, neutrophil oxygen radical production had decreased and was not different from normal. Pre-dialysis, significant plasma protein oxidation was evident from reduced free sulfhydryl groups, increased carbonyl groups, and increased advanced oxidation protein products. Post-dialysis, plasma protein free sulfhydryl groups had increased to normal levels, while plasma protein carbonyl groups increased slightly, and advanced oxidation protein products remained unchanged. The results of this study show that neutrophil oxygen radical production normalizes during high-flux dialysis, despite a transient increase early in dialysis. This decrease in oxygen radical production is associated with an improvement in some, but not all, measures of protein oxidation.

Angiogenin: A Novel Inhibitor of Neutrophil Lactoferrin Release during Extracorporeal Circulation

Degranulation of polymorphonuclear leukocytes (PMNL) occurs during extracorporeal circulation. A degranulation-inhibiting protein identical to angiogenin was recently isolated from high-flux dialyzer ultrafiltrate. This protein inhibits the release of lactoferrin and metalloproteinases from PMNL in vitro. In the present study, we investigated end-stage renal disease patients undergoing regular hemodialysis treatment with either high-flux dialyzers (n = 51) or low-flux dialyzers (n = 44), and chronically uremic patients undergoing hemodiafiltration (n = 30). Hemodialysis therapy with low-flux polysulfone or cellulose triacetate membranes caused no or only minimal reduction (≤8%) of plasma angiogenin levels within 2 h of dialysis treatment associated with a 1.6-fold lactoferrin release from PMNL. Hemodialysis therapy with high-flux membranes (e.g. cellulose triacetate, polymethylmethacrylate) or hemodiafiltration resulted in a reduction of plasma angiogenin levels by 20–40% after 2 h associated with a nearly 4-fold PMNL lactoferrin release. The release of PMNL elastase was not affected by the different treatment modalities used. We conclude that high angiogenin plasma levels protect against lactoferrin release from PMNL during extracorporeal circulation in chronically uremic patients. A decrease of plasma angiogenin between 20 and 40% during extracorporeal circulation, however, results in marked PMNL lactoferrin release. This novel mechanism may explain, at least in part, PMNL degranulation also in non complement activating high-flux membranes.

Solvent treatment of CTA hollow fiber membrane and its pervaporation performance for organic/organic mixture

Cellulose triacetate (CTA) hollow fiber membrane used to separate methanol/methyl tert-butyl ether (MTBE) by pervaporation (PV) has been prepared from CTA hollow fiber reverse osmosis (RO) membrane for desalination of brackish water with high salinity. Acetone was selected as a modification agent of CTA membrane. PV performance depended on the solvent concentration, the treatment time and modification temperature of CTA RO hollow fiber membrane soaked in the aqueous acetone. The results show that CTA hollow fiber membrane modified with the solvent has a superior performance both the separation factor and the permeate flux in the PV experiment conditions.

Detection of campylobacter species: a comparison of culture and polymerase chain reaction based methods

Aims: To investigate the optimal method for the detection of campylobacters from stool samples by comparing selective culture with membrane filtration and the polymerase chain reaction (PCR). Methods: Three hundred...

Faster phenytoin removal from serum by electrodialysis: a potential use in hemodialysis?

Protein binding of drug is responsible of ineffectiveness of conventional hemodialysis. The aim of the present study was to investigate the potential of electrodialysis, i.e. the transport of charged solutes through a membrane under the influence of an external electric potential, to increase the clearance of phenytoin, i.e. a model albumin-bound drug from human serum in vitro. Electrodialysis was performed through cellulose triacetate membrane mounted onto electrodialyser built in-house which separated: (a) saline solution, (b) 4% albumin saline solution or (c) human serum and dialysate compartments. The electric current density between both electrodes placed into donor (cathode) and dialysate (anode) compartments was settled to 0.79 mA/cm 2 for 3 h at 37 °C. Recovery of phenytoin in dialysate from either (a) saline solution or (b) 4% albumin saline solution was significantly higher than that obtained by classical dialysis ((a): 42% versus 24%; (b): 30% versus 6%). In human serum, the effectiveness of electrodialysis was appreciated by the unbound phenytoin clearance, which was about twice higher than in dialysis (0.22 ml/h versus 0.12 ml/h). However, the removed fraction of 10% in the human serum could just reflect the usual unbound phenytoin. Consequently, the impact of electrodialysis on the protein binding was not affirmed, but the ability of this technique to eliminate shortly free drug was clearly demonstrated. Electrodialysis would be a promising improvement of hemodialysis for the elimination of ionized drugs from human blood.

Effect of dialysis on serum/plasma levels of free immunoglobulin light chains in end-stage renal disease patients.

Free immunoglobulin light chains (FLCs) have previously been shown to be uraemic toxins. In this work we investigated the effect of haemodialysis and haemodiafiltration on the level of FLCs in serum/plasma of uraemic patients. Serum/plasma proteins were separated by non-reducing SDS-PAGE and transferred to a nitro-cellulose membrane. FLCs were detected by specific antibodies and an enhanced chemiluminescence detection system. The FLC concentrations were calculated. We studied 15 healthy subjects, 10 patients with chronic renal failure, 71 patients undergoing haemodialysis treatment and 33 patients treated with haemodiafiltration. Different membranes were compared: low- and high-flux polysulfone membranes, low- and high-flux cellulose triacetate membranes, high-flux polymethylmethacrylate and polyacrylonitrile membranes. Chronic renal failure patients showed elevated FLC concentrations as compared with controls. In haemodialysis or haemodiafiltration patients these values were even higher. This was mainly due to an increased concentration of FLC of the lambda-type. The treatment modality per se did not influence the FLC concentrations. Only haemodialysis or haemodiafiltration with the polymethylmethacrylate membrane lead to a significant reduction in FLC concentrations; however, these did not reach control levels. We did not observe differences in FLC levels between patients with different underlying diseases, nor did we find a correlation between age or the duration of the dialysis treatment and FLC concentrations. We found a positive correlation between FLC concentrations at the beginning of dialysis treatment and the amount of IgLCs removed during treatment. However, the average FLC level after treatment did not reach control values. Currently available haemodialysis or haemodiafiltration treatments are unable to normalize the elevated serum/plasma levels of FLCs in end-stage renal disease patients.

Radiation grafting studies of acrylic acid onto cellulose triacetate membranes

Polymer surface modifications were obtained by the application of radiation treatments, etching and grafting of acrylic acid monomers on different membranes of cellulose triacetate materials. Cellulose triacetate foils from pellet dissolution and commercial cellulose triacetate solid state nuclear track detector membranes were assayed. Irradiation with fission fragments from Cf-252 source to obtain a porous structure, 25 MeV proton beam and Co-60 γ-source to produce peroxides were employed in the experiments. The present work gives the grafting yield of AAc monomer onto CTA membranes as a function of diverse variables including irradiation parameters ( γ-dose, Cf-252 ff irradiation time, proton fluency and electronic energy loss (d E/d x) e), structural parameters (pore diameter and pore density, etching time and etching temperature) and grafting parameters (monomer and Mohr salt concentration, grafting time and grafting temperature).

Serum neopterin monitoring and vitamin E-modified, regenerated hemodialyzer membrane influence on biocompatibility.

The exposure of blood to hemodialysis membranes results in numerous phenomena and/or complications in hemodialyzed patients, which have an influence on the quality of life (QOL) of those patients. A vitamin E-modified regenerated cellulose membrane (E-membrane) was developed to act as a scavenger for reactive oxygen species causing complications in hemodialysis patients. Neopterin (NEOP) is a metabolite derived from guanosine triphosphate with the production and release of NEOP being induced in monocytes and macrophages by cytokines such as interferon-gamma (IFN-gamma). Serum neopterin levels are shown to be a reactive marker of bioincompatibility of dialysis membranes in hemodialysis patients. The following report evaluates the usefulness of serum NEOP as a marker for the biocompatibility of the E-membrane hemodialyzer in a clinical study. In the clinical study, where extracorporeal ultrafiltration strategies with E-membranes were employed, the serum levels of NEOP were lower than those in patients using cellulose triacetate membranes (C-membranes). In the long-term evaluation of the biocompatibility of E- and C-membranes, the increase of serum neopterin levels in the C-membrane was higher than those in the E-membrane. In conclusion, the evaluation of serum neopterin levels during hemodialysis shows that the E-membrane has a good biocompatibility in hemodialyzed patients.

Tailoring the Properties of Asymmetric Cellulose Acetate Membranes by Gas Plasma Etching

Cellulose triacetate (CTA) ultrafilters and cellulose acetate blend (CAB) desalination membranes were treated with a radiofrequency gas plasma (tetrafluoromethane (CF4) or carbon dioxide (CO2), 47–49 W, 0.04–0.08 mbar). Treatment times were varied between 15 s and 120 min. The plasma-treated top layer of the membranes was characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, and contact angle measurements to obtain information about surface structure, chemistry, and wettability, respectively. The membrane properties (e.g., permeability, selectivity, fouling) were studied by waterflux measurements, molecular weight cutoff measurements, and fouling experiments with bovine serum albumin. CO2 plasma treatment resulted in gradual etching of the membrane's dense top layer. Permeation and selectivity changed significantly for treatment times of 0–15 min for CTA and 5–60 min for CAB membranes. Moreover, CTA membranes were hydrophilized during CO2 plasma treatment whereas CF4 plasma treatment led to hydrophobic surfaces due to strong fluorination of the top layer. This study shows that gas plasma etching can tailor the properties of asymmetric cellulose acetate membranes by simultaneously modifying the chemistry and structure of the top layer. The low fouling properties of CTA membranes were thereby largely maintained.

A Glucose Biosensor Based on Electro-Enzyme Catalyzed Oxidation of Glucose Using a HRP-GOD Layered Assembly

The assembly and the characterization (by DC cyclic voltammetry and flow injection analysis (FIA) mode) of a bienzymatic biosensor for glucose is described. The biosensor is constituted by a glucose oxidase (GOD)-entrapping cellulose triacetate membrane, layered onto a polymeric membrane (polystyrene cross-linked with 1 % divinyl benzene functionalized with tributylmethyl phosphonium chloride (TBMPC)) embedding horseradish peroxidase (HRP), previously blocked onto a pyrolitic graphite electrode (PGE). Under flowing conditions, the biosensor, which gives place to direct, unmediated electron-transfer, responds linearly to the glucose up to 5.0 mM with a precison always better than 5 %, and the detection limit was 0.07 mM. The influence of different experimental parameters, like temperature, flow rate, applied potential, interferents, etc., has been evaluated. For what concerns the potential interferences, no interfering species, as ascorbic acid, urea, etc., affects the biosensor response. The biosensor, characterized by an operational stability of at least twenty days, has been successfully tested on real samples.

Mechanism of facilitated saccharide transport through plasticized cellulose triacetate membranes

Mechanistic insight is gained for saccharide transport through plasticized cellulose triacetate (CTA) membranes containing lipophilic ion-pair transport carriers. The molecular structures of the different membrane components are systematically varied and diagnostic transport characteristics such as saccharide–carrier diffusion constant and saccharide extraction constant are determined. The observed percolation thresholds support a jumping mechanism, however, the diffusion constants are found to decrease as the size of the saccharide, carrier cation, and carrier anion increase, indicating that the rate-limiting step in the transport process involves diffusion of a complex comprised of all three components. The data is reconciled in terms of mobile-site jumping mechanism where the saccharide is relayed along a sequence of ion-pair carriers that are locally mobile. In an attempt to improve saccharide selectivity, calix-[4]-arene dicarboxylates were evaluated as potential ditopic transport carriers. This produced no major change in saccharide extraction constants.

A triacetate cellulose membrane for the separation of methyl tert-butyl ether/methanol mixtures by pervaporation

Sorption and pervaporation experiments were carried out with cellulose triacetate membranes for the separation of methyl tert-butyl ether and methanol mixtures. The sorption experiments show that with an increase of MeOH concentration in the feed, the membrane swelling ratio increases first until a maximum value is reached and then remains constant. On the other hand, the MeOH concentration in the sorped phase first decreases to a minimum value and then increases with the transition occurring near the azeotropic point. In the pervaporation experiments, the total and MeOH permeation fluxes were found to increase with the increase of MeOH concentration in the feed while the MTBE permeation flux first increases and then decreases. The total permeation fluxes are significantly enhanced with an increase in temperature. This temperature dependence is more pronounced at low MeOH concentration, but the extent of increase of the total permeate flux is relatively constant when MeOH concentrations are greater than 10%, and it can be described by the Arrhenius law. Selectivity decreases with the increase of MeOH concentration and becomes more or less constant at high MeOH concentrations.

Hemodialysis machine with one-touch volume replacement and one-touch hemodialysis completion

In order to encourage the spread of home hemodialysis, we have developed a hemodialysis machine that enables “one-touch” voluem replacement and “one-touch” hemodialysis completion, by modifying a viscous pump-type hemodialysis machine. When emergency volume replacement is needed, pressing the volume replacement button will serve to transfer 200 ml of dialysate to the blood side as a replacement fluid, at 100 ml/min within the dialyzer. Pressing the completion procedure button when the hemodialysis is over causes 420 ml of the dialysate to be transferred to the blood side, at 100 ml/min within the dialyzer, so that the blood within the dialyzer and the blood tubing is replaced by the thus-transferred dialysate. The two puncture needles on the arterial and venous sides are then removed, and the hemodialysis completion procedure is finished. In a trial, the new hemodialysis machine, together with a cellulose triacetate membrane artificial kidney, was used a total of 144 times over a period of 4 months in three outpatients receiving maintenance hemodialysis. With the machine, 32 emergency volume replacements were performed. Both the hemodialysis completion and the emergency volume replacement procedure were performed uneventfully.

Influence of various hemodialysis membranes on the plasma (1→3)-β-D-glucan level

Recently, invasive fungal infections have increased significantly because of the growing number of immunocompromised hosts. The measurement of plasma (1-->3)-beta-D-glucan has been proposed as a useful diagnostic tool for deep mycosis. In this study, we analyzed the alteration of the plasma (1-->3)-beta-D-glucan concentration by using different kinds of hemodialysis (HD) membranes in end-stage renal disease (ESRD) patients and estimated its half-life. Twenty-seven patients with ESRD without known fungal infections (with a median age of 66 years old) were enrolled in this study. Cellulose triacetate (CTA) membrane, cellulose (Cu) membrane, and polymethyl methacrylate (PMMA) membrane were used in three consecutive initiations of HD and plasma (1-->3)-beta-D-glucan concentration was measured before and after each HD session. The level did not change between before and after HD when CTA and PMMA membranes were used. In contrast, the plasma (1-->3)-beta-D-glucan level increased greatly after HD using the Cu membrane (from 9.4 to 332 pg/mL in median). Hypothesizing that the plasma (1-->3)-beta-D-glucan level declines exponentially, its median half-life is estimated at 20 hours, which is not affected by hepatic or renal function. Because the plasma (1-->3)-beta-D-glucan level increases dramatically after HD using the Cu membrane, dialyzers with Cu membrane should be avoided for HD in patients with suspected deep mycosis. The measurement of plasma (1-->3)-beta-D-glucan is also useful for the patients with hepatic or renal failure.

INVESTIGATION OF SALICYLATE INTERFERENCE ON ANION SELECTIVE ELECTRODES1*

Several types of ion-selective membranes were tested to decrease the salicylate interference in clinical measurements of chloride. The study included electrodes with methyldodecylammonium salt and membrane matrices of poly(vinyl chloride) (PVC), silicone rubber (SR) and cellulose triacetate (CTA). The first two membranes were modified by the ultra- filtration (UF) and nanofiltration (NF) membranes, respectively, the cellulose triacetate membrane was modified by alkaline hydrolysis. The most significant and useful decrease by one and half order of magnitude of log KCl, Sal pot was observed for the silicone rubber membrane with additional nanofilter membrane. Dedicated to Prof. George Baiulescu on his 70th anniversary