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Dialysis Membrane (dialysis + membrane)

Distribution by Scientific Domains

Life Sciences	35%

Selected Abstracts

Biological Reactions Resulting from Endotoxin Adsorbed on Dialysis Membrane: An In Vitro Study

ARTIFICIAL ORGANS, Issue 2 2004
Kenji Tsuchida
Abstract:, Some types of dialysis membrane are known to adsorb endotoxin (ET). It is suggested that the biocompatibility of dialysis membrane is enhanced by adsorption and inhibition of ET. This study attempts to clarify the membrane-mediated biological reaction of the ET that is adsorbed to a dialysis membrane. After a dialysis circuit was prepared, contaminated dialysate was introduced on the dialysate side of a polyether polymer alloy (PEPA) membrane that adsorbs ET while saline solution or blood were introduced on the blood side, and the difference in ET adsorption between the two set-ups was measured. Further, the side filled with blood was left standing for 2 h, after which the changes in the amount of interleukin 1 receptor antagonist (IL-1Ra) produced from the whole blood were also assayed. Significantly more ET was adsorbed to the dialysis membrane when blood rather than saline was on the other side. In addition, the IL-1Ra production from the dialysis membrane that adsorbed ET was significantly higher. The ET adsorbed to the dialysis membrane may influence a living body even if it does not pass through the membrane. Accordingly, it is difficult to assume that the adsorption of ET to the membrane enhances its biocompatibility. [source]

Low-Flux Versus High-Flux Synthetic Dialysis Membrane in Acute Renal Failure: Prospective Randomized Study

ARTIFICIAL ORGANS, Issue 12 2001
Jadranka Buturovi, Ponikvar
Abstract: The influence of dialyzer membrane on the morbidity and mortality of patients with acute renal failure remains a matter of debate. The aim of the prospective randomized clinical study was to assess the influence of the flux of a synthetic dialyzer membrane on patients' survival rate, restitution of renal function, and duration of hemodialysis treatment of patients with acute renal failure as a part of multiorgan failure. Seventy-two patients treated in intensive care units of the University Medical Center Ljubljana were randomized according to the dialyzer used throughout the duration of hemodialysis treatment. There were 38 patients in the low-flux group (dialyzer F6, low-flux polysuphone, Fresenius, Bad Homburg, Germany) and 34 patients in the high-flux group (dialyzer Filtral 12, sulphonated high-flux polyacrylonitrile, Hospal, Industrie Meyzieu, France). Both groups were balanced in terms of sex, age, APACHE II score, oliguria before dialysis, cause of acute renal failure, innotropic support, mechanical ventilation, and the number of failing organs. The patients' survival rate was 18.7% in the low-flux group and 20.6% in the high-flux group. Ten patients (26.3%) recovered their renal function in the low-flux group and 8 (23.5%) in the high-flux group. Hemodialysis treatment lasted 11.2 days in the low-flux and 10.7 days in the high-flux group. An analysis of subgroups with a lower mortality rate (subgroup of patients without oliguria and subgroup of patients with less than 4 failed organ systems) did not show significant differences between the low-flux and high-flux groups in terms of survival rate, recovery of renal function, and duration of hemodialysis treatment. In conclusion, no significant differences were found in the results of low-flux versus high-flux synthetic membrane dialyzer treatment in patients with acute renal failure as a part of multiorgan failure in terms of survival rate, recovery of renal function, incidence of oliguria during hemodialysis, and duration of hemodialysis treatment. The number of failing organs seems to be the most important single factor determining the survival of patients with acute renal failure as a part of multiorgan failure. [source]

Effects of a Vitamin E-Modified Dialysis Membrane and Vitamin C Infusion on Oxidative Stress in Hemodialysis Patients

ARTIFICIAL ORGANS, Issue 6 2001
Jaromír Eiselt
Abstract: Hemodialysis deteriorates oxidative stress. Vitamin E is an antioxidant whose regeneration is provided for by vitamin C. The authors tested the effects of a vitamin E-modified membrane (E), nonmodified cellulose membrane (O), and vitamin C infusion (500 mg, C) into the arterial blood line during dialysis on parameters of oxidative stress. In a short-term study, 24 patients were subjected to a single dialysis session with E, O, E with C, and O with C protocols. In a long-term study (12 weeks), 20 patients were randomized into groups with C and without C on each dialysis, and both groups had dialysis using O, E, and again O membrane for 4 weeks each. In the short-term study, thiobarbituric acid reacting substances (TBARS) in plasma rose after dialysis (p < 0.02) with O, and no changes were observed in the other 3 protocols. In the long-term study, predialysis TBARS declined when using E both in the groups with C (p < 0.02) and without C (p < 0.05). A switch over to O resulted in TBARS returning to baseline levels. The E membrane prevented an increase in lipid peroxidation during single dialysis, and long-term use of the E membrane also resulted in a decrease in the predialysis lipid peroxidation level. The antioxidant capacity of the E membrane was not enhanced by vitamin C infusion. High doses of vitamin C administered during dialysis using a nonmodified cellulose membrane prevented an increase in lipid peroxidation, most probably due to the enhanced rate of endogenous vitamin E regeneration. [source]

Amperometric Biosensors Based on Choline Oxidase Entrapped in Polyacrylamide Microgels

ELECTROANALYSIS, Issue 2-3 2007
López, M. Sánchez-Paniagua
Abstract A choline amperometric biosensor has been designed using as biological component choline oxidase (ChOx) entrapped in polyacrylamide microgels. The working electrode was prepared by holding the enzyme loaded microgels on a platinum electrode by a dialysis membrane. It was found that the optimum microgel cross-linking required to retain ChOx and to allow the diffusion of choline was 7.0%. The response of the biosensor was optimized in relation to pH, temperature and working potential and the following optimal values were obtained: pH,9.0, temperature range between 20 and 30,°C, and potential +0.6,V. Under optimal conditions the sensitivity for choline was 17.45,mA M,1 cm,2, the detection limit 8,,M, and the response linear range from 2×10,5 M to 2×10,4 M. This biosensor has been also used as a nicotine detector due to the inhibition of the catalytic activity of choline oxidase by this compound. Moreover, the simultaneous entrapment of a second enzyme, acetylcholinesterase (AChE), in the microgels makes the biosensor sensible to acetylcholine. [source]

Evaluation of a Dialysis Sampler's Integrity in a Cold Climate

GROUND WATER MONITORING & REMEDIATION, Issue 1 2008
O. Iwakun
The use of a diffusion sampler made from regenerated cellulose dialysis membrane was investigated in this study to resolve issues from previous studies on the integrity of the sampler when deployed in the field. The dialysis samplers were deployed in monitoring wells at two upstream oil- and gas-contaminated sites. The average ambient temperature in the monitoring wells was 4 ± 1°C over the 6 month duration of the test. Burst pressure and tensile strength tests were used to determine the integrity of the samplers at two field sites over time. The test results showed no adverse impacts on the samplers' integrity after 6 months. Therefore, diffusion samplers from regenerated cellulose dialysis membrane show promising results when used for long-term monitoring associated with natural attenuation assessment under the conditions tested. [source]

In vitro new dialysis protocol to assay the antiseptic properties of a quaternary ammonium compound polymerized with denture acrylic resin

LETTERS IN APPLIED MICROBIOLOGY, Issue 3 2004
C. Pesci-Bardon
Abstract Aims:, To develop an in vitro protocol in order to assess the antiseptic properties of a quaternary ammonium compound polymerized with acrylic denture resin base, using experimental resin discs and dialysis membranes. Methods and Results:, Experimental acrylic resin discs were polymerized with Poly 202063A, an ammonium compound (2,50%). Antiseptic properties were assayed against two reference strains (Escherichia coli, Staphylococcus aureus) and a laboratory strain (Candida albicans), using three different conditions (test A, B and C). In test A, according to classical protocols the resin discs were first soaked in large volumes of microbial inoculum (45 ml). An original dialysis protocol was then designed to recreate the small biofilm volume on the prosthetic surface. In test B, discs and bacterial inoculum (600 ,l) were introduced in a dialysis bag and dialysed against a sterile buffer. A bactericidal effect was observed against E. coli and Staph. aureus (<0·1% viable cells in initial bacterial suspension). A dose-dependent fungistatic effect was observed against C. albicans. Finally, in test C discs and sterile buffer (600 ,l) were introduced in a dialysis bag and dialysed against microbial inoculum. Reduced activity was found outside the dialysis bag, demonstrating that free ammonium was able to diffuse through the dialysis membrane, displaying antiseptic properties. Conclusions:, The present protocol demonstrated that a quaternary ammonium compound remains efficient after heat polymerization with an acrylic denture base resin, both in immediate and distant microbial environments. Significance and Impact of the Study:, Such removable prosthetic devices with intrinsic antiseptic properties would contribute to improve the long-term management of denture stomatitis. [source]

Matching Efficacy of Online Hemodiafiltration in Simple Hemodialysis Mode

ARTIFICIAL ORGANS, Issue 12 2008
Detlef H. Krieter
Abstract PUREMA H (referred to as PES) is an innovative dialysis membrane for enhanced low-molecular-weight (LMW) protein removal. The purpose of the study was to prove whether its efficacy in hemodialysis (HD) matches that of online hemodiafiltration (HDF) with conventional high-flux membranes. In a prospective, randomized, cross-over study on eight maintenance dialysis patients, treatment efficacy of HD with PES was compared with online postdilution HDF with the two synthetic high-flux membranes polysulfone (referred to as PSU) and Polyamix (referred to as POX). Apart from the infusion of replacement fluid, which was set at 20% of the blood flow rate of 300 mL/min, operating conditions in HD and HDF were kept identical. Small solute and LMW protein plasma clearances as well as the reduction ratio (RR) of cystatin C and retinol-binding protein were not different between the therapies. HDF with POX resulted in a significantly lower myoglobin RR as compared with HD with PES, and HDF with PSU. A 4% higher beta2 -microglobulin RR was determined in HDF with PSU (73 ± 5%) as compared with PES in HD (69 ± 5%). The albumin loss was below 1 g for all treatments. Despite the fact that simple HD did not fully exploit the characteristics of PES, it achieved essentially similar LMW protein removal and albumin loss as compared with online postdilution HDF with the conventional synthetic high-flux membranes PSU and POX. Therefore, HD with PES may have beneficial effects on the outcome of maintenance dialysis patients similar to high-efficiency HDF. [source]

Biological Reactions Resulting from Endotoxin Adsorbed on Dialysis Membrane: An In Vitro Study

The Bradykinin Response and Early Hypotension at the Introduction of Continuous Renal Replacement Therapy in the Intensive Care Unit

ARTIFICIAL ORGANS, Issue 12 2001
J. Stoves
Abstract: We assessed the relationship of certain clinical variables (including bradykinin [BK] release and dialysis membrane) to initial mean arterial pressure (MAP) reduction in 47 patients requiring continuous renal replacement therapy (CRRT) in an intensive care unit. The pretreatment MAP was 84 ± 14 mm Hg for the group as a whole. The initial MAP reduction was 11.5 (7,20) mm Hg, occurring 4 to 8 min after connection. MAP reduction was 9 (6,15) mm Hg with polyacryonitrile (PAN) membranes versus 14 (5-19) mm Hg with polysulfone (PS) (not significant). There were positive correlations between MAP reduction and BK concentration at 3 (BK3; r = 0.58, p < 0.01) and 6 (BK6; r = 0.67, p < 0.001) min with PAN but not with PS. A greater reduction in MAP was seen in patients who were not receiving inotropic support (Mann-Whitney test, p < 0.01). BK3 and BK6 values for the PAN and PS groups were not significantly different. However, BK concentrations greater than 1,000 pg/ml were only seen with PAN (6 patients, MAP reduction 27 [17,31] mm Hg). There were positive (albumin) and negative (age; acute physiology, age, and chronic health evaluation score; C-reactive protein [CRP]; calcium) correlations with BK3/BK6 in the PAN and PS groups, some of which (albumin, CRP) reached statistical significance. In summary, MAP reduction at the start of CRRT correlates with BK concentration. The similarity of response with PAN and PS suggests an importance for other clinical factors. In this study, hemodynamic instability was more likely in patients with evidence of a less severe inflammatory or septic illness. [source]

Application of cellulose-based self-assembled tri-enzyme system in a pseudo-reagent-less biosensor for biogenic catecholamine detection

BIOTECHNOLOGY JOURNAL, Issue 5 2007
Mikhail L. Rabinovich Professor
Abstract Amorphous cellulose was used as a specific carrier for the deposition of self-assembled multienzyme complexes capable of catalyzing coupled reactions. Naturally glycosylated fungal cellobiohydrolases (CBHs) of glycosyl hydrolase families 6 and 7 were specifically deposited onto the cellulose surface through their family I cellulose-binding modules (CBM). Naturally glycosylated fungal laccase was then deposited onto the preformed glycoprotein layer pretreated by ConA, through the interaction of mannosyl moieties of fungal glycoproteins with the multivalent lectin. The formation of a cellulase-ConA-laccase composite was proven by direct and indirect determination of activity of immobilized laccase. In the absence of cellulases and ConA, no laccase deposition onto the cellulose surface was observed. Finally, basidiomycetous cellobiose dehydrogenase (CDH) was deposited onto the cellulose surface through the specific interaction of its FAD domain with cellulose. The obtained paste was applied onto the surface of a Clark-type oxygen electrode and covered with a dialysis membrane. In the presence of traces of catechol or dopamine as mediators, the obtained immobilized multienzyme composite was capable of the coupled oxidation of cellulose by dissolved oxygen, thus providing the basis for a sensitive assay of the mediator. Swollen amorphous cellulose plays three different roles in the obtained biosensor as: (i) a gelforming matrix that captures the analyte and its oxidized intermediate, (ii) a specific carrier for protein self-assembly, and (iii) a source of excess substrate for a pseudo-reagent-less assay with signal amplification. The detection limit of such a tri-enzyme biosensor is 50-100 nM dopamine. [source]

Effects of Interspecific Interactions between Microcystis aeruginosa and Chlorella pyrenoidosa on Their Growth and Physiology

INTERNATIONAL REVIEW OF HYDROBIOLOGY, Issue 3 2007
Min Zhang
Abstract Interactions between Microcystis aeruginosa and Chlorella pyrenoidosa were analyzed by flow cytometry and by phytoplankton pulse-amplitude-modulated fluorimetry (Phyto-PAM) in joint cultures as well as in cultures separated by dialysis membranes. Results showed that the growth of C. pyrenoidosa was greater than that of M. aeruginosa, and that the growth of M.aeruginosa but not the growth of C. pyrenoidosa was significantly inhibited by the interactions between M. aeruginosa and C. pyrenoidosa. Culture filtrates of these two algae showed no apparent effects on the growth of the competing species. For M. aeruginosa, decreases in esterase activity, chlorophyll a fluorescence, and maximum quantum yield were observed in joint cultures, indicating that the metabolic activity and photosynthetic capacity of M.aeruginosa were suppressed. Light limitation from the shading effect of C. pyrenoidosa may be the main reason for such inhibition. For C. pyrenoidosa, esterase activity was suppressed in membrane-separated and joint cultures, suggesting that C.pyrenoidosa was probably affected by allelopathic substances secreted by M.aeruginosa. However, no significant difference was observed in the chlorophyll a fluorescence and maximum quantum yield of C. pyrenoidosa in the two cultures. In addition, interspecific interactions induced a reduction in size in both M. aeruginosa and C.pyrenoidosa, which may contribute to the development of C. pyrenoidosa dominance in the present study. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

In vitro new dialysis protocol to assay the antiseptic properties of a quaternary ammonium compound polymerized with denture acrylic resin

Serum Neopterin Monitoring and Vitamin E-Modified, Regenerated Hemodialyzer Membrane Influence on Biocompatibility

ARTIFICIAL ORGANS, Issue 1 2002
Katsunori Yoshida
Abstract: 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-, (IFN-,). 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. [source]

Immunoaffinity removal of xenoreactive antibodies using modified dialysis or microfiltration membranes

BIOTECHNOLOGY & BIOENGINEERING, Issue 2 2003
Sujatha Karoor
Abstract Hyperacute rejection following xenogeneic transplantation in primates is mediated by naturally occurring IgM antibodies, which are specifically directed to ,-Galactosyl residues on many nonprimate mammalian cells. Current approaches to remove these anti-,Gal IgM include plasmapheresis followed by immunoaffinity adsorption on bead columns using synthetic Gal epitopes, which requires two pieces of complex equipment. In this study, we explored the use of immunoaffinity adsorption with hollow fiber microporous or dialysis membranes to which a synthetic ,Gal trisaccharide ligand is bound. Covalent attachment of ligand directly to the surface produced negligible binding, but use of long-chain polyamines as reactive spacers yielded binding densities for anti-,Gal IgM as high as 89 mg/mL membrane volume in breakthrough curve experiments with microporous nylon membranes having an internal surface area of 4.2 m2/mL membrane volume. A crossflow microfilter fabricated from the membranes described in this study and having about 0.4 m2 luminal surface area would be able to carry out plasma separation and immunoadsorption in a single device with a large excess of binding capacity to ensure that all plasma that filters across the device and is returned to a human patient is essentially free of anti-,Gal IgM. We conclude that immunoaffinity removal of xenoreactive antibodies using microfiltration hollow fiber membranes is feasible and has potential advantages of efficiency and simplicity for clinical application. © 2002 Wiley Periodicals, Inc. Biotechnol Bioeng 81: 134,148, 2003. [source]