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PubMed1980

[Reducing hemodilution through ultrafiltration following cardiopulmonary bypass].

Reduction of post-bypass-hemodilution by ultrafiltration was assessed. Five dogs were subjected to 1 hour of cardiopulmonary bypass and were hemodiluted with 2 liters of Ringer lactate solution to a hematocrit below 20%. An arterial hemofilter was then incorporated into the system and 1 liter of fluid was ultrafiltrated for 16 minutes during partial bypass. The filtrate was free of protein and hemoglobin. There was a significant increase of the hematocrit from 19 to 29%, and protein from 2,7 to 5,4 g%. No hemodynamic alterations were seen during or after filtration. Osmolality remained within normal limits (from 284 to 296 mOsm/kg). In addition, no electrolyte imbalance was found. The method is therefore safe for quick volume removal without the side effect of diuretics.

Animals↗
PubMed1981

Gas-chromatographic assay of free phenytoin in ultrafiltrates of plasma: test of a new filtration apparatus and specimen stability.

I describe a gas-chromatographic procedure involving a nitrogen detector for "free" (or "unbound") phenytoin in the concentration range 0.2-4.0 mg/L in ultrafiltrates of plasma. The CV (n = 10) for the assay was 2.9% for a 0.49 mg/L concentration, 1.5% for 2.02 mg/L. The sensitivity was 0.05 mg/L. The ultrafiltration process ("Ultra-Free" filters) used to separate the free phenytoin fraction from the bound fraction was tested. The mean of and CV for free phenytoin concentrations measured in eight replicate serum filtrates were 0.68 mg/L and 15%; for eight replicate plasma filtrates the values were 0.42 mg/L and 2.9%. Thus serum is not suitable for this procedure. Storage of plasma before filtration under a wide variety of times and temperatures has an insignificant effect upon the filtration process. Some evidence was found of occasional protein "leakage" through the filters.

Chromatography, Gas↗
PubMed1975

Ultrafiltration for middle molecules in uraemia.

An ultrafiltration system for the purification of toxic substances is demonstrated. Using this system, it is possible to eliminate substances with a molecular weight up to 5,000 in the same amount as smaller molecules. The clearances for smaller molecules are lower and for larger molecules higher compared to haemodialysis and they depend mainly on the ultrafiltrate flow. Amino acid loss did not exceed the amount which was eliminated by plate haemodialysers. Side effects, such as excessive haemolysis, platelet or fibrinogen depletion, were not to be found.

Amino Acids↗
PubMed1977

Ultrafiltration for improved assay of urinary enzymes.

Ultrafiltration of urine and rapidly separates urinary enzymes from inhibitors, activators, and heat-stable, spurious activities present in urine. Using eight enzymes of clinical interest as examples, we verified the reliability of results obtained after ultrafiltration by comparsion with results obtained after gel filtration.

Acetylgalactosamine↗
PubMed1996

An unsuspected cause of excessive ultrafiltration during maintenance hemodialysis.

Undetected excessive ultrafiltration occurred in a patient on maintenance hemodialysis using a Gambro AK-10 monitor and Ergo 120 A-G blood lines. In spite of alarms present on the hemodialysis monitor, the dialysis staff were not alerted of the failure. The patient had nausea, vomiting, abdominal cramps and hypotension. The monitor was withdrawn from service and subjected to careful technical checks, but no failure could be detected. Thorough investigation of the hemodialysis 'set-up' at the time of the incident revealed a partial obstruction (kinking) to have occurred in the extracorporeal blood circuit where the flexible tubing joined the venous chamber. This had created a very high positive pressure within the dialyzer compartment and excessive ultrafiltration, which the blood circuit pressure monitoring transducer was unable to detect. To prevent kinking of the blood lines, dialysis staff and patients should be instructed to ensure that blood lines lie in smooth curves.

Aged↗
PubMed1996

[Determination of total free erythrocyte carnitine in an ultrafiltrate of hemolysate].

The authors described an assay procedure for the determination of free and total carnitine in red blood cells. This method is based on ultrafiltration of the broken red blood cells in Centrisart filter, by centrifugation. Free and total carnitine in ultrafiltrates is determined by the spectrophotometric method of Cederblad and Coll., adapted to Cobas-Fara. They evaluated the procedure linearity, reproductability and analytical recovery. Comparison with precipitate protein procedure showed that results correlated well. The advantages of this original assay include simplicity, increase rapidity, lower cost of reagents and mainly improved reproductability.

Carnitine↗
PubMed1996

Isolation of NADH from Saccharomyces cerevisiae by ether permeabilization and its purification by affinity ultrafiltration.

Cells of Saccharomyces cerevisiae were permeabilized by ether for the isolation of coenzyme NADH. A 4-fold increase in the ether fraction to aqueous fraction resulted in the recovery of 80% of total NADH present in the cell. NADH was separated and purified by affinity ultrafiltration using yeast alcohol dehydrogenase as an affinity ligand. The binding characteristics of the enzyme and coenzyme were established at different pH and ionic strengths using gel filtration. The number of moles of NADH bound per mole of alcohol dehydrogenase (r) was found to be 5.7 at pH 8 and ionic strength (I) 0.1 M. The binary complex of NADH and alcohol dehydrogenase was cleaved by lowering the pH to 6.0. The crude cell permeate on purification by ultrafiltration with 2-fold dilution, gave NADH with an absorbance ratio (A260/A340) of 2.3 and overall yield of 68%. Alcohol dehydrogenase was recovered as retentate with 93% recovery and 15% loss in activity.

Alcohol Dehydrogenase↗
PubMed1977

Partial purification of human lymphocyte-activating factor (LAF) by ultrafiltration and electrophoretic techniques.

Lymphocyte-activating factor (LAF) has been produced by culturing human peripheral blood leukocytes in the presence of lipopolysaccharide and autologous human serum. The major LAF activity, identifiable by Sephadex chromatography (m.w. 13,000) was separated from most serum proteins in the culture medium by ultrafiltration with a hollow fiber device. Sucrose gradient isoelectric focusing of the concentrated ultrafiltrate yielded a single peak of LAF activity with an average isoelectric point of pH 6.8. Semi-preparative polyacrylamide gel electrophoresis of the isoelectric focusing sample resulted in separation of the LAF activity from detectable amounts of serum proteins. The recovered LAF activity was estimated to be purified more than 16,000-fold and is judged to be active in submicrogram amounts.

Animals↗
PubMed1997

Peritoneal ultrafiltration and refractory congestive heart failure.

This prospective nonrandomized study enrolled 16 patients with congestive heart failure [NYHA (New York Heart Association) III and IV] refractory to a maximal well-tolerated drug therapy. The aims were to evaluate if peritoneal ultrafiltration (PUF) could improve clinical conditions and to determine morbidity secondary to resistant congestive heart failure (RCHF) and PUF. There were 16 patients (12 male, 4 female) with a mean age of 65.4 years (56-81 years) and follow-up of 15.6 months (4-33 months). Thirteen patients had RCHF without end-stage renal disease. Patients were classified as NYHA class IV (n = 11) or class III (n = 5). One anuric patient had been on previous hemodialysis and switched to APD. PUF was obtained with a 2-L hypertonic dialysis solution, once a day (n = 7) or every 2 days (n = 4). Clinical improvement was obtained for all the patients. Weight decreased from 72.2 to 66.7 kg with a weekly ultrafiltration of 3.74 L (2.2-6.5 L). Sodium removal was 79 mmol/day (urinary 43%, peritoneal transport 57%). During the follow-up period, 2 patients received a cardiac transplant since 7 died due to cardiac reasons. Mean hospitalization time was 4.4 and 1.20 per patient per day before and after PUF, respectively. Hospitalization was in keeping with either RCHF (36%), dialysis complications (16%), or miscellaneous causes (48%). Our experience showed that a functional improvement and a better quality of life were achieved for all these patients with a low rate of hospitalization.

Aged↗
PubMedDate not supplied

Involvement of reactive oxygen species in human sperm arcosome reaction induced by A23187, lysophosphatidylcholine, and biological fluid ultrafiltrates.

Although recent evidence indicated that the production of reactive oxygen species (ROS) by human spermatozoa may be involved in the regulation of capacitation, very little is known about the role of ROS in the acrosome reaction. To address this issue, Percoll-washed spermatozoa were incubated in Ham's F-10 medium in the absence (no capacitation) or presence (capacitation) of fetal cord serum ultrafiltrate (FCSu) or progesterone. The effects of the ROS scavengers, superoxide dismutase (SOD), and catalase were then tested on the acrosome reaction induced by lysophosphatidylcholine (LPC), A23187, and ultrafiltrates from follicular fluid (FFu) and FCSu, as well as on the protein tyrosine phosphorylation associated with this process. 2-Methyl-6-(p-methoxyphenyl)-3,7-dihydroimidazo [1,2-a] pyrazin-3-one (MCLA)-amplified chemiluminescence was used to determine the extracellular superoxide (O2.-) production from spermatozoa. The observations that both SOD and catalase reduced (in the case of LPC) or totally prevented (in the other cases) the acrosome reaction of capacitated spermatozoa and that hydrogen peroxide (H2O2) or ROS generated by the combination of xanthine and xanthine oxidase (O2.-, which dismutates to H2O2) triggered the acrosome reaction indicated the involvement of ROS in this process. In fact, capacitated spermatozoa in which the acrosome reaction was induced by LPC, A23187, and FFu produced more O2.- than noncapacitated spermatozoa treated with the same agents. A23187 and LPC had minor effects on protein tyrosine phosphorylation of noncapacitated spermatozoa. However, these inducers caused a decrease in tyrosine phosphorylation of Triton-soluble proteins (mainly those of 37, 42, and 47 kDa) from capacitated spermatozoa, a decrease more pronounced in the presence of SOD. On the other hand, there was a marked increase in tyrosine phosphorylation of few proteins (70 to 105 kDa) from the Triton-insoluble fraction, which was partly reversed by SOD (in the case of LPC and A23187) or catalase (in the case of A23187), or abolished in the presence of the two antioxidants (in the case of A23187). These data indicate that the acrosome reaction is associated with an extracellular O2.- generation by spermatozoa and that both O2.- and H2O2 may be involved in the regulation of this process. The mechanism by which these ROS act is unknown but may involve tyrosine phosphorylation of sperm proteins.

Acrosome Reaction↗
PubMed1998

Hygiene aspects of drinking water ultrafiltration.

Ultrafiltration is highly effective method for removal of bacteria and viruses and does not produce organohalides associated with water treatment by chlorine gas. The aim was to assess the hygiene suitability of the unit for possible use in bottled water production. The ultrafiltration unit was in operation for 220 hours with simulated of varying duration. The running time (220 hours) and shut-down duration (to 5 hours) did not in any way influence the effectiveness of the module (100% filtration of aerobic colony count at 37 degrees C and 22 degrees C).

Colony Count, Microbial↗
PubMed1997

Pharmacokinetics of elemental platinum (ultrafiltrate and total) after a thirty minute intravenous infusion of ormaplatin.

Preclinical data suggest that ormaplatin (tetrachloro-(dl-trans)-1, 2-diamminocyclohexaneplatinum) has substantial activity in cisplatin-resistant tumor models and may be less nephrotoxic than cisplatin. Based on these data we initiated a phase I clinical trial in patients with refractory metastatic cancer. This report characterizes the pharmacokinetic profile of both the total plasma concentrations of elemental platinum and the unbound ultrafiltrate concentrations of elemental platinum, following a 30 min intravenous infusion of ormaplatin. Platinum concentrations were determined by AAS, and pharmacokinetic parameters for both the total plasma concentration and the ultrafiltrate concentration of elemental platinum were determined using both compartmental and noncompartmental methods. Twenty-eight patients (14 males and 14 females; median age, 58) received ormaplatin. There was a linear relationship between Cmax and dose (r2 = 0.945) and AUC and dose (r2 = 0.976). Ormaplatin is more accurately described by a two-compartment model than by a one-compartment model. The distribution half-life (t1/2 alpha) was 0.3 h and the terminal half-life (t1/2 beta) was 39.1 h. The volume of the central compartment (V) was 68.6 L and the volume of distribution at steady state (Vdss) was 183 L. Like total plasma platinum, unbound platinum is also best characterized by a two-compartment model. The elimination of free platinum is also biphasic with a distribution half-life (t1/2 alpha) of 0.3 h and a terminal half-life (t1/2 beta) of 19.3 h. The mean volume of the central compartment (V) was 200.5 L, and the mean volume of distribution at steady state (Vdss) was 560.5 L. Clinical development of ormaplatin has been terminated due to increased frequency of neurological complications noted over other platinum agents; however, the pharmacokinetics are, in general, similar to those of other clinically used platinum compounds.

Adult↗
PubMed1988

Plasma ultrafiltration as successful therapy of rabbit VX-2 carcinoma.

It has been demonstrated that tumor-bearing animals elaborate a low molecular weight (less than 10,000 daltons) factor capable of inhibiting in vitro lymphocyte function. It was postulated that removal of this factor would have a favorable effect on host immune response that would translate into improved tumor control. A study was conducted in rabbits bearing the VX-2 carcinoma. Ultrafiltration (UF) was performed 10 days following IV tumor inoculation. UF was achieved by passing blood through an Amicon Diafilter (molecular weight cutoff 10 kD) positioned between the arterial and venous cannulae after heparinization. Two plasma volumes of ultrafiltrate were removed with continuous saline replacement. Two groups of animals received the nonspecific immunoadjuvant, Detox, at time of therapy. Survival in the UF group (N = 9) was compared to untreated tumor-bearing animals (N = 10), sham-operated animals (N = 6), animals receiving Detox (N = 7), and animals receiving UF plus Detox (N = 6). UF imparted a survival advantage when compared to controls (mean 35 days vs. 25 days, P less than .01). The sham group had survival identical to controls. Detox alone conferred minimal survival advantage (mean 29 days, P greater than .05). However, UF + Detox demonstrated maximal survival benefit (mean 40 days, P less than .01). We conclude that UF is an effective anticancer modality in this preclinical model. This study suggests that efforts aimed at eliminating suppressor molecules in cancer patients may be of benefit, especially when combined with biological response modifiers such as Detox.

Adjuvants, Immunologic↗
PubMed1993

Determination of platinum in urine, ultrafiltrate, and whole plasma by isotope dilution gas chromatography-mass spectrometry compared to electrothermal atomic absorption spectrometry.

Isotope dilution gas chromatography-mass spectrometry (GC-MS) and electrothermal atomic absorption spectrometry (EAAS) are compared for platinum (Pt) determination in urine, plasma ultrafiltrate, and plasma samples from a patient undergoing cisplatin therapy. The isotope dilution GC-MS method is based on the use of lithium bis(trifluoroethyl)dithiocarbamate as a chelating agent and enriched 192Pt as an internal standard. Pt isotope ratios were measured using a Finnigan MAT 8230 organic mass spectrometer, and Pt concentrations were calculated from different sets of isotope ratios in the molecular ion of the Pt-chelate. In the EAAS method, Pt concentrations were determined using three different approaches. These were: (i) calibration curve based on aqueous standards containing Pt in 10% HCl, (ii) standard addition, and (iii) matrix digestion followed by standard addition. Good agreement was obtained for Pt concentrations determined by GC-MS and EAAS in urine samples while there were significant differences in Pt concentrations of ultrafiltrate and whole plasma samples by the two methods. Discussion of possible reasons for these differences emphasizes the need for future critical evaluation of these methods.

Carcinoma, Squamous Cell↗
PubMed1996

Scintigraphic Study of Local Flux and Osmotic Pressure Distributions in Ultrafiltration of Blood and Plasma.

We have investigated the spatial variation of local protein concentration and filtration flux by a scintigraphic technique in the ultrafiltration of bovine albumin solutions and blood. The feed was mixed with (99m)Tc albumin macroaggregates and circulated through a polysulfone 30,000 MWCO hollow fiber filter placed in the field of a gamma-camera. Concentration profiles c(b) (x) were reconstructed from scintigraphic images and the local ultrafiltration flux was calculated by differentiating c(b) (x) and using mass conservation. Tests were run at various inlet shear rates from 472 to 1415 s(-1) and under two different filtration regimes: no net filtration (permeate valve closed) and large filtration (below the pressure independent plateau). The data confirm the filtration decay from the filter inlet to outlet but an unexpected result is the presence of high retrofiltration in the downstream part of the filter length in the case of large filtration. This retrofiltration can be explained by a high osmotic pressure at the membrane created by the protein polarization concentration. Assuming a constant pressure gradient along the fibers, it is possible to estimate the local osmotic pressure at the onset of retrofiltration and to infer from it the protein concentration at the membrane, which is found to vary from 170 to 250 g/liter when gamma(w) increases. Similar experiments were run with blood and a microfiltration membrane (0.55-µm pores). In that case no retrofiltration was obtained, which confirms our explanation since in this case the polarization layer is composed of red cells which exert no osmotic pressure.

Journal Article↗
PubMed1996

On the Behavior of Micellar Solutions in Tangential Ultrafiltration Using Mineral Membranes

Tangential ultrafiltration associated with the technology of mineral membrane is expected to offer several advantages compared to stirred cell ultrafiltration (often used at the laboratory level): (i) easier operating and cleaning procedures; (ii) better resistance to corrosion; (iii) reduced concentration polarization effects. The behavior of surfactant micelles, which can be used as the extracting phase in such processes, has been given little attention so far. The present work was aimed at investigating the behavior of different kinds of surfactants from the viewpoints of the permeate flux and of the amount of surfactant passing through the membrane. We have used two types of zirconium-titanium oxide membranes with molecular weight cutoff of 10,000 or 15,000 Da. The influence of parameters such as applied pressure, retentate flow rate, added salt, and value of pH was taken into consideration. The results obtained with cetylpyridinium chloride (CPC, cationic), sodium dodecyl sulfate (SDS, anionic), and polyethylene glycol tert-octylphenyl ether (Triton X-100, nonionic) are discussed in terms of their possible interactions with (or adsorption onto) the membranes and their supporting material.

Journal Article↗
PubMed1996

Analysis of Initial Protein Surface Coverage on Fouled Ultrafiltration Membranes

Internal surface coverage of protein in membranes during the initial phase of ultrafiltration was analyzed. Bovine serum albumin (BSA), in solutions of pH 5 and 7 with 0.05 and 0.15 M NaCl, were ultrafiltered with 100,000-MWCO polysulfone membranes. Mass uptake of the membranes was determined using electron paramagnetic resonance spectroscopy for separate membranes for fractions of an hour for up to 4 h. The resulting data were compared with models for surface coverage. The results showed a significant amount of protein loading exists in a very short time of exposure during ultrafiltration. The amount of material found in this period was not a function of solution properties; however, solution properties did affect the resistance per mass for adsorbed species when the pH was near the isoelectric point of BSA. The modeling comparison implied that the entrained solute from pH 7 appeared to behave as though it was lodged in the ultrathin skin area of the membrane. Solute in the membrane at pH 5 and low ionic strength appeared to be lodged and adsorbed throughout the membrane substructure.

Journal Article↗
PubMed1999

Use of Micellar-Enhanced Ultrafiltration at Low Surfactant Concentrations and with Anionic-Nonionic Surfactant Mixtures.

Micellar-enhanced ultrafiltration is a separation technique which can be used to remove metal ions or dissolved organics from water. Metal ions bind to the surface of negatively charged micelles of an anionic surfactant while organic solutes tend to dissolve or solubilized within the micelles. The mixture is then forced through an ultrafiltration membrane with pore sizes small enough to block passage of the micelles and associated metal ions and/or dissolved organics. Monomeric or unassociated surfactant passes through the membrane and does not contribute to the separation. This paper considers advantages of addition of small concentrations of nonionic surfactant to an anionic surfactant; the resulting anionic-nonionic mixed micelles exhibit negative deviation from ideality of mixing which leads to a smaller fraction of the surfactant being present as monomer and a subsequently larger fraction present in the micellar form. The addition of nonionic surfactant improved the separation of divalent zinc substantially at total concentrations above the critical micelle concentration (cmc) of the anionic surfactant. Both zinc and tert-butylphenol (a nonionic organic solute) show unexpected rejection at surfactant concentrations moderately below the cmc, where micelles are absent. This is considered as due to a higher surfactant concentration in the gel layer adjacent to the membrane where micelles are present. Reduction of this rejection at lower transmembrane pressure drops supports this mechanism. Some rejection of zinc was observed in the absence of surfactant but not of tert-butylphenol, indicating an additional effect of membrane charge for ionic solutes. Copyright 1999 Academic Press.

Journal Article↗