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PubMed1993

Interrelation of humoral factors, hemodynamics, and fluid and salt metabolism in congestive heart failure: effects of extracorporeal ultrafiltration.

PURPOSE: We investigated the mechanisms involved in the regulation of salt and water metabolism in patients with congestive heart failure (CHF). Extracorporeal ultrafiltration was utilized as a nonpharmacologic method for withdrawal of body fluid. PATIENTS, METHODS, AND RESULTS: In 32 consecutive patients with CHF (New York Heart Association functional class II to IV) and different degrees of water retention, 24-hour diuresis and natriuresis were inversely best correlated with the combination of circulating renin, aldosterone, norepinephrine, and renal perfusion pressure (RPP, mean aortic pressure minus mean right atrial pressure). Fluid withdrawal (600 to 5,000 mL) at a rate of 500 mL/h, until right atrial pressure decreased to 50% of baseline, caused variable humoral, circulatory, and diuretic effects that were mainly related to the extent of fluid retention. In fact, in 10 patients (Group 1) with overhydration refractory to drug therapy and with urinary output less than 1,000 mL/24 h (mean, 370 mL), soon after the procedure, plasma renin (-39%), aldosterone (-50%), and norepinephrine (-47%) were reduced and RPP was increased (+16%), and in the subsequent 24 hours, diuresis was increased by 493%; in 9 patients (Group 2) whose baseline urinary output exceeded 1,000 mL/24 h (mean, 1,785 mL), renin increased by 40%, norepinephrine, aldosterone, and RPP each decreased by 12%, and diuresis remained unchanged; in 13 patients (Group 3) with a daily urinary excretion as in Group 2 and without overhydration, RPP decreased (-7%), renin (+196%), aldosterone (+170%), and norepinephrine (+52%) increased, and diuresis decreased by 45%. There was an overall correlation (p < 0.0001) between the combination of changes in these circulatory and hormonal variables and changes in diuresis and natriuresis with ultrafiltration. CONCLUSIONS: It appears that in CHF, (1) retention of sodium and water results from an interaction of hormonal and hemodynamic (primarily RPP) alterations that may exert a reciprocal positive feedback; (2) depending on the presence and severity of fluid retention, the response to withdrawal of body fluid may vary from neurohumoral activation and restriction of diuresis to neurohumoral depression and extreme potentiation of salt and water excretion; (3) refractory CHF requires the interruption of the humoral-hemodynamic vicious circle, and ultrafiltration is able to accomplish that.

Adult↗
PubMed1988

Preparation of human cord sera for enzymatic triglyceride assays: removal of free glycerol by ultrafiltration.

Enzymatic triglyceride assays that generate glycerol from triglycerides as a part of the enzymatic process in quantitating serum triglyceride levels give elevated values when external free glycerol is present. Our objective was to develop an ultrafiltration technique that would remove exogenous and/or endogenous free glycerol from small aliquots of human cord sera so that accurate serum triglyceride values could be obtained with the commercially available triglyceride assay kits. Exogenous glycerol was completely removed from cord sera when the samples were washed twice with saline in Amicon Centricon-30 microconcentrators. This ultrafiltration technique lowered cord serum triglyceride levels significantly (P less than 0.001), but had no effect on cord total serum cholesterol levels. A comparison of washed and unwashed cord sera by either polyacrylamide or agarose gel electrophoresis indicated that the serum protein and lipoprotein profiles were not altered by the ultrafiltration process.

Cholesterol↗
PubMed1990

An ultrafiltration assay for lysyl oxidase.

A modification of the original microdistillation assay for lysyl oxidase is described in which Amicon C-10 microconcentrators are used to separate, by ultrafiltration, the 3H-labeled products released from a [4,5-3H]-lysine-labeled elastin substrate. Enzyme activity is determined by scintillation counting of the ultrafiltrate, after subtraction of radioactivity released in the presence of beta-aminopropionitrile, a specific inhibitor of the enzyme. Conditions are described which optimize both the sensitivity and the efficient use of substrate. The assay shows linear inhibition of activity in up to 1 M urea; hence, as the enzyme is normally diluted in the assay, samples in 6 M urea can be assayed directly, without prior dialysis, and corrected for partial inhibition. Comparable results are obtained when enzyme activity is assayed by ultrafiltration or microdistillation. The assay is simple and convenient and, by using disposable containers throughout, it eliminates the need for time-consuming decontamination of radioactive glassware.

Amino Acid Oxidoreductases↗
PubMed1978

Bovine milk xanthine oxidase: purification by ultrafiltration and conventional methods which omit addition of proteases: some criteria for homogeneity of native xanthine oxidase.

Methodological difficulties have been encountered when proteases were omitted from the conventional isolation of bovine milk xanthine oxidase (xanthine:oxygen oxidoreductase, EC 1.2.3.2). The use of these conventional methods has been studied and modified to reduce the problems encountered. Some of the difficulties may be due to the presence of high concentrations of caseins, which exhibit a wide range of charges and sizes, thereby making separations based on charge and size more complicated. In addition, non-covalent interactions may occur between the caseins and xanthine oxidase leading to the formation of casein-xanthine oxidase micellar aggregates. The difficulties encountered in this conventional isolation have been circumvented by purifying the enzyme directly from milk fat globule membranes that first have been washed free of most casein and other milk proteins. The xanthine oxidase is isolated by ultrafiltration through an Amicon XM-100A membrane at 5 degrees C in 0.25 M sucrose/5 mM sodium salicylate. The largest molecular size of globular proteins which can penetrate this ultrafiltration membrane has been previously estimated to be around 100 000 daltons. Xanthine oxidase thus appears to be smaller than 100 000 daltons in its native state. The size observed for active xanthine oxidase previously isolated by other methods has been around 275 000--300 000 daltons. Xanthine oxidase isolated by ultrafiltration appears similar to xanthine oxidase from conventional isolation methods according to empirical criteria of homogeneity based on size and also on the absorbances at 280 and 450 nm. Criteria based on charge were found to be less reliable.

Ammonium Sulfate↗
PubMed1977

The analysis of free tryptophan in human blood with the Ultrafiltrator: a comparison with other methods.

Recently, the Ultrafiltrator has been described, in the literature, which allows the ultrafiltration of small molecules in minute blood samples under anaerobic conditions with filters of any pore size. This apparatus has been tested for the separation of free tryptophan in heparinised and EDTA-plasma and in whole blood. At the same time, free tryptophan has been analysed after ultrafiltration with CF-50 A and CF-25 membrane cones (Centriflo). The results obtained by these two techniques are compared. Finally, a comprehensive review of other methods reported in the literature, concerning the isolation of free tryptophan, is presented.

Blood Proteins↗
PubMed1991

Total and ultrafiltrable plasma magnesium in hyper- and hypoparathyroidism, and in calcium-related metabolic disorders.

Serum total, ultrafiltrable and protein-bound magnesium, and urinary fractional excretion of magnesium were studied in patients with primary hyperparathyroidism (before and after surgery) and in patients with hyperparathyroidism, malignant hypercalcemia and chronic renal failure with or without hemodialysis. Whereas serum total Mg was unchanged in patients with primary hyperparathyroidism, the ultrafiltrable magnesium concentration was higher than in the control group and higher before than after surgery. The total and the ultrafiltrable magnesium concentrations were highly correlated in the overall patients with Ca-related metabolic disorders, suggesting that renal function had no influence on the relation between these two parameters. Moreover, in malignant hypercalcemia, our results suggested that PTH-like peptides might be less effective than PTH in renal handling of Mg as previously described for Ca.

Adult↗
PubMed1991

Measurement of plasma free steroids by direct radioimmunoassay of ultrafiltrate in association with the monitoring of free components with [14C]glucose.

We describe a modified method of centrifugal ultrafiltration using the Grace MPS-3 device for the measurement of plasma free (unbound) steroids (cortisol, testosterone, estradiol, and prednisolone). Plasma was incubated with [14C]glucose to monitor the movement of free components, applied to the MPS-3 and centrifuged. Steroid concentration of ultrafiltrate was directly measured by radioimmunoassay, and multiplied by the ratio of [14C]glucose count (dpm) in plasma to [14C]glucose count (dpm) in ultrafiltrate. The data by this method correlated well with those obtained by equilibrium dialysis. Our results of free steroid in healthy volunteers and patients with various diseases were comparable with the previously reported values. This procedure showed the advantages of small sample volume, rapid separation and the ability to process a large number of samples in a single run.

Adolescent↗
PubMed1990

The nonlinear characteristics of soft gels and hydrated connective tissues in ultrafiltration.

A one-dimensional ultrafiltration problem of fluid flow through a soft permeable tissue or gel under high pressure and compressive strain is solved. A finite deformation biphasic theory is used to model the behavior of the soft porous permeable solid matrix. This theory includes a Helmholtz free energy function which depends on the three principal invariants (I, II, III) of the right Cauchy-Green tensor and which satisfies the Baker-Ericksen inequalities on the principal stresses and strains. The dependence of the porosity phi f and the solidity phi s on deformation is deduced and a generalization of the exponential strain-dependent functional form for the permeability, k = k0 exp (M epsilon), of Lai and Mow (Biorheology 103, 111-123, 1980) is proposed. In this one-dimensional problem, we show that the dependence of the permeability on phi f, phi s, and III is equivalent to its dependence on hydration as proposed by Fatt and Goldstick (J. Colloid Sci. 20, 962-988, 1965). The exact solution of the ultrafiltration problem is derived and asymptotic and numerical methods are used to evaluate it. For high pressures and finite strains, the solution provides some surprising effects. The theory predicts that a material starting with a homogeneous porosity will have a strongly non-homogeneous porosity throughout the column during ultrafiltration. The resulting change in pore size through the filtration column may be very important in understanding its filtration characteristics. It is also found that there is a long delay time, up to 10 to 15 min, before the filtration velocity reaches an equilibrium. In filtration experiments where the rate of mass transport across the tissue or column of gel is important, sufficient time must be allowed for the steady state to be reached.

Animals↗
PubMed1989

A method for removing interleukin-1- and tumor necrosis factor-inducing substances from bacterial cultures by ultrafiltration with polysulfone.

The ability of human mononuclear cells (MNC) to produce cytokines is a highly sensitive and biologically relevant test system for the presence of microbial products. The safety of parenteral fluids is presently determined by gelation of the limulus amebocyte lysate (LAL) to endotoxin. In the present study, crude bacterial culture supernatants from Escherichia coli were subjected to ultrafiltration using polysulfone and the ultrafiltrates were tested for their ability to stimulate human MNC. Total interleukin-1 (IL-1) and tumor necrosis factor (TNF) produced by MNC were measured by radioimmunoassay. Endotoxin-like substances in E. coli cultures are rejected by a factor of at least 100,000. Rejection takes place by molecular size exclusion and by absorption. The sensitivity of the LAL and MNC cytokine production were comparable. These studies demonstrate a wide margin of safety for the production of parenteral fluids using ultrafiltration for endotoxin-containing materials.

Bacterial Toxins↗
PubMed1984

Validation and use of centrifugal ultrafiltration-dialysis in the measurement of percent free oestradiol in serum.

The validity of the centrifugal ultrafiltration-dialysis method in the measurement of the percentage of oestradiol and testosterone which is not bound to protein (free) in human serum was assessed. In an initial validation, the values of % free steroid obtained for oestradiol and testosterone in protein-free ultrafiltrates of human serum were higher than expected. Filter paper discs used in the system were shown to adsorb [3H]oestradiol from protein-free solution. Their replacement with glass-fibre discs, which did not adsorb oestradiol, decreased but did not eliminate the discrepancy between observed and expected results for % free oestradiol in ultrafiltrates. The use of polyethylene rather than polypropylene vials then reduced the discrepancy to insignificant levels. The estimates for % free oestradiol in serum were reduced by these modifications.

Centrifugation, Density Gradient↗
PubMed1987

Centrifugal ultrafiltration-dialysis for non-protein-bound oestradiol in blood: importance of the support.

The percentage of non-protein-bound oestradiol in serum or other fluid measured by centrifugal ultrafiltration-dialysis was critically dependent on the supporting medium used to collect the ultrafiltrate. When either Whatman No. 1 filter paper discs, Whatman GF/D glass fibre discs or Celite were used, the ratios of 3H-steroid to [14C]glucose on the support were found to change with centrifugation time. This occurred when serum or protein-free filtrates were analysed and was eliminated when silanised Celite was employed as the support. It was also observed that when serum was analysed, the [3H]/[14C] ratio inside the cell increased linearly with centrifugation time and this was ascribed to the small changes in volume which occurred inside the cell as ultrafiltrate accumulated on the support. It was concluded that the correct time to sample the ratio of [3H]/[14C] inside was before centrifugation.

Carbon Radioisotopes↗
PubMed1984

Pulmonary edema: reversal by ultrafiltration.

Ultrafiltration, the process by which plasma water is removed from the blood was utilized to determine its effect on lowering lung water in pulmonary edema produced by fluid overload, steam inhalation, and endotoxin. Lung water was measured by the thermal-dye indicator dilution technique which correlated well with lung water measured gravimetrically over a wide range (r = 0.95). Edema was produced by fluid overload in five mongrel dogs (Group I), by steam inhalation (Group II), and by endotoxin (Group III). Extravascular lung water (EVLW) rose significantly (P = less than 0.05) from control levels with the production of the edematous states (Group I: 8.0 ml/kg (mean) +/- 1.9 (SD) to 13.1 +/- 1.9); (Group II: 8.1 +/- 1.0 to 10.7 +/- 0.7); (Group III: 7.4 +/- 0.9 to 10.3 +/- 1.2). EVLW then fell significantly (P = less than 0.05) after ultrafiltration in all three groups (Group I: 8.9 +/- 2.4; Group II: 7.8 +/- 1.9; Group III: 7.7 +/- 1.4). Ultrafiltration was effective in reversing pulmonary edema and may have clinical application when excess lung water interferes with cardiac or pulmonary function.

Animals↗
PubMed1975

Inhibition of glyceraldehyde 3-phosphate dehydrogenase by plasma and serum ultrafiltrates due in part to a low-molecular-weight, nonpeptide material.

In an attempt to verify the existence in the blood of a diabetogenic peptide (somantin) derived from growth hormone, ultrafiltrates from plasma and serum from normal and diabetic subjects were prepared. The freeze-dried residues of these ultrafiltrates inhibited glyceraldehyde 3-phosphate dehydrogenase as somantin is claimed to do. However, the behavior of the inhibitory material on gel filtration on Sephadex G-10 indicated a molecular weight well below 700, rather than the considerably larger size claimed for somantin. The inhibitory material did not adsorb to Dowex 50W cation exchange resin at pH 2.5, while over 95 percent of ninhydrin-positive material was retained. Acid hydrolysis of the inhibitory material did not abolish its activity. Because of the presence of this low-molecular-weight, nonpeptide inhibitory material, inhibition of glyceraldehyde 3-phosphate dehydrogenase by a simple ultrafiltrate of plasma or serum is probably not a definitive measure of somantin.

Adult↗
PubMed1996

Determination of the two diastereoisomers of lobaplatin (D-19466) in plasma ultrafiltrate of cancer patients with a normal or an impaired kidney or liver function by high-performance liquid chromatography with ultraviolet detection.

Lobaplatin consists of two diastereoisomers, LP-D1 and LP-D2. Being a new cytostatic agent it represents platinum compounds of the third generation and is active in several in vitro tumor models of murine and human origin. To determine the pharmacokinetics of LP-D1 and LP-D2 in cancer patients with and without a normal kidney and liver function, an HPLC procedure was developed and validated. Plasma ultrafiltrate samples were injected into the HPLC system after solid-phase extraction. The standard curves of LP-D1 and LP-D2 in plasma ultrafiltrate were linear over the range 0.071-9.100 and 0.067-8.639 microM, respectively. The recovery from plasma ultrafiltrate was 84% for both diastereoisomers. The within-day accuracy ranged from 98.1 to 100.3% for LP-D1 and from 96.5 to 106% for LP-D2. The between-day accuracy ranged from 99.2 to 101.5% fro LP-D1 and 97.7 to and < or = 6.5% for LP-D2, respectively. For pharmacokinetic purposes the method proved to be sufficiently sensitive, specific and accurate for analysing clinical samples.

Antineoplastic Agents↗
PubMed1989

The binding of 99mTc(Sn)-MDP complexes to human serum albumin and other blood proteins determined with gel chromatography and ultrafiltration.

The binding of 99mTc(Sn)-MDP to human serum albumin and other blood proteins was investigated by gel chromatography and ultrafiltration. During gel chromatography dissociation of the 99mTc(Sn)-MDP-protein complex occurs: thus, it is not a suitable technique for the determination of protein binding. The values found with ultrafiltration have to be corrected for non-ultrafiltrable TcO2.nH2O. From the corrected values it can be concluded that binding of 99mTc(Sn)-MDP to blood proteins does not play a role in the biodistribution.

Blood Proteins↗
PubMed2006

The changes in NT-proBNP plasma concentrations during dialysis are highly dependent of the dialysis membrane ultrafiltration coefficient.

BACKGROUND: NT-proBNP is a powerful marker with diagnostic and pronostic value for heart failure. It is of particular interest in patients with end-stage renal disease who are at high risk for heart failure. The aim of this study was to investigate the effect of hemodialysis on plasma NT-proBNP concentrations. METHODS: NT-proBNP concentration was measured in 67 patients before and after hemodialysis. RESULTS: In the 20 patients dialyzed with a membrane whose ultrafiltration coefficient was below or equal to12, NT-proBNP concentration was comparable after and before dialysis (16611+/-21024 vs. 15216+/-19027 pg/ml, NS). At the opposite, in the 47 patients dialyzed with a membrane whose ultrafiltration coefficient was above or equal to 40, NT proBNP concentration was 35% lower after dialysis compared to before dialysis (11983+/-21819 vs. 18574+/-31862 pg/ml, p<0.0001). CONCLUSIONS: In patients dialyzed with a membrane whose ultrafiltration coefficient is high, dialysis is likely to decrease results by one third. Thus sampling blood before dialysis in hemodialyzed patients appears as the best time to stratify the cardiovascular risk in these patients.

Aged↗
PubMed2004

Comparison of ultrafiltration and solid phase extraction for the separation of free and protein-bound serum copper for the Wilson's disease diagnosis.

BACKGROUND: The determination of the ratio free/protein-bound serum copper along with urinary copper can be used as a preliminary test for the Wilson's Disease diagnosis. In this work, the determination of these copper fractions in serum samples was carried out in two different ways; after separation of the copper bound to proteins from the free fraction by a column for protein adsorption and by ultrafiltration. As proteins can be adsorbed onto plastic polymeric surfaces, polyethylene (PE) with different molecular weights in powder form was investigated for protein adsorption. A small column was adapted in a flow system to carry out a solid-phase extraction (SPE) on-line. Preliminary experiments defined conditions for protein retention and elution and column saturation. Good performance was achieved using Mg(NO3)2 solution as carrier and methanol as eluent. The presence of proteins in both fraction (column effluent and eluate) was checked by the Coomassie Brilliant Blue test. Copper was measured by graphite furnace atomic absorption spectrometry. The measurement in the column effluent furnished the free-fraction of copper while the copper measured in the eluate the bound-fraction. The method was compared with ultrafiltration (20 kDa), measuring the free-copper in the ultrafiltrate. For the determination of protein-bound copper, the copper found in the ultrafitrate was discounted from the total copper measured in the sample. RESULTS: Serum samples of 10 individuals were analyzed by both methods with good agreement of the results. The regression plots, obtained by analysing the samples by both methods, presented r2 and slope of 0.97 and 0.96 for free copper and 1.00 and 1.00 for bound copper, respectively. Protein-bound copper (PB) concentrations ranged from 74 to 2074 microg/l and free-copper (F) from 22 to 54 microg/l. The ratio F/PB, calculated from SPE data, was 29.7% for one individual, with Wilson Disease well-characterized, and ranged from 1.2% to 5.2% for the others. CONCLUSION: The SPE method performed well in terms of accuracy and precision, and showed good agreement with the UF. Advantages of SPE are small sample volume (50 microl), separation carried out in 10 min, and the use of the same column for several analyses.

Blood Proteins↗
PubMed2006

Determination of unbound docetaxel and paclitaxel in plasma by ultrafiltration and liquid chromatography-tandem mass spectrometry.

This work describes the development of a straightforward method for the determination of free docetaxel and paclitaxel in plasma. The separation of bound and unbound drug was performed with ultrafiltration. Different ultrafiltration devices were evaluated, especially regarding non-specific binding to the device. The most appropriate device for this application was selected and a procedure to counteract non-specific binding to the ultrafiltrate collection cup was developed. This consisted of a wash procedure with methyl t-butyl ether. A liquid/liquid extraction with methyl t-butyl ether was performed and samples were analysed with a previously developed liquid chromatography-tandem mass spectrometry procedure. The method used a Merck Purospher Star RP-18 column (55 mm x 2.0 mm, 3-microm particle size) and electrospray in the positive mode. A triple quadrupole instrument was used to monitor MRM transitions. Small modifications to this procedure were made to ensure adequate sensitivity. Within- and between-day reproducibility did not exceed 15% and accuracy ranged between 94.4 and 102.5%. The calibration range of the method was from 0.4 to 100 ng/ml both for paclitaxel and docetaxel. Finally, a fast and relatively simple method could be developed.

Antineoplastic Agents, Phytogenic↗