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PubMed2005

Extracorporeal ultrafiltration for acute exacerbations of chronic heart failure: report from the Acute Dialysis Quality Initiative.

This report from a work group affiliated with the Acute Dialysis Quality Initiative is a critical assessment of the use of extracorporeal ultrafiltration (UF) in the management of acutely decompensated heart failure (HF). In addition to assessing UF in this setting, the report also provides background information on HF, including classification, pathophysiology, and the importance of concomitant renal failure. A summary of important results from clinical trials in this area is provided, along with a discussion of technical considerations. Finally, specific recommendations for future clinical evaluations are given.

Heart Failure↗
PubMed1999

Circadian variation in serum free ultrafiltrable insulin-like growth factor I concentrations in healthy children.

The aim of the present study was to assess 24-h free IGF-I profiles in serum in healthy children using an ultrafiltration method that approached in vivo conditions. Five girls and two boys aged 10.4 to 13.6 (mean 12.2) years with pubertal stages I to III were studied. A fasting blood sample was drawn at 0800 h, and thereafter samples were drawn at specific times every 20 min until 0800 h the next morning. Free IGF-I, IGF binding protein 1 (IGFBP-1), and insulin were analyzed in 1-h samples, total IGF-1 in 2-h samples, and GH in 20-min samples. A statistically significant diurnal variation in serum free IGF-I was seen (p < 0.001) with peak values between 0900 and 1200 h in the morning and a nocturnal decrease with a nadir at 0700 h (p < 0.05). Concomitantly with the decrease in free IGF-I an increase in IGFBP-1 was observed between 0200 and 0700 h (p < 0.001). Total IGF-I did not exhibit any diurnal variation. Inverse relationships between the 24-h area under the curve (24-hAUC) free IGF-I and 24-hAUC IGFBP-1 (p = 0.002) and between fasting free IGF-I and fasting IGFBP-1 levels (p-0.01) were observed. Furthermore, 24-hAUC GH correlated with fasting free IGF-I (p = 0.04), 24-hAUC free IGF-I (p = 0.03), fasting total IGF-I (p = 0.04), and 24-hAUC total IGF-I (p = 0.04). No phase relationship between free IGF-I and IGFBP-1 or insulin were seen. In healthy children, circulating free IGF-I exhibits a nocturnal decrease and an increase in the morning. The diurnal secretion of free IGF-I correlates with GH and is inversely related to IGFBP-1. The metabolic significance of these findings needs further study.

Adolescent↗
PubMed2004

Extracorporeal elimination of large concentrations of tirofiban by zero-balanced ultrafiltration during cardiopulmonary bypass: an in vitro investigation.

The short-acting platelet glycoprotein IIb/IIIa antagonist tirofiban is beneficial when used in the context of cardiac surgery. Tirofiban has an elimination half-life of 2 h. Renal failure prolongs the half-life and continues inhibition of platelet aggregation refractory to transfusions of platelets. Extracorporeal elimination is necessary to prevent excessive hemorrhage in this condition. We assessed the elimination of tirofiban by hemofiltration in an in vitro model of cardiopulmonary bypass (CPB). Two hemofilters and one plasmapheresis filter were assessed. Three separate filters of each type were tested serially. The CPB circuit was primed with a total volume of 1000 mL. Tirofiban was added to a calculated concentration of 200 ng/mL. Portions of 50 mL of filtrate were retrieved from the dialyzer, and equal amounts of fluid were substituted in the circuit. After each filtration, the tirofiban blood level was analyzed. The procedure was repeated 16 times. Peak tirofiban concentrations ranged from 160 to 260 ng/mL. The elimination of tirofiban followed an exponential decay curve with fast clearance of the large therapeutic concentrations of 250 to 50 ng/mL. The subsidence coefficient b revealed no significant differences in elimination between the filter systems. These data suggest that ultrafiltration is an effective means for extracorporeal elimination of therapeutic levels of tirofiban.

Cardiopulmonary Bypass↗
PubMed1991

Binding characteristics of dopa (3,4-dihydroxyphenylalanine) and its metabolites to bovine serum albumin as measured by ultrafiltration technique.

The interaction between 3,4-dihydroxyphenylalanine (DOPA), dopamine, 3-methoxytyramine and homovanillic acid and bovine serum albumin (BSA) was investigated by the ultrafiltration technique. The apparent binding constants were determined assuming the equivalence and independence of the binding sites on the BSA molecule. The binding constants were in the range of log K = 2.85 to 3.77 with 1 to 2 binding sites. The affinity of ligands to BSA strengthened with progression of the metabolism in the order of DOPA less than dopamine less than 3-methoxytyramine less than homovanillic acid.

Animals↗
PubMed1989

Clinical significance of renal hemodynamics in severe congestive heart failure: responsiveness to ultrafiltration therapies.

Isolated ultrafiltration, hemodialysis & peritoneal dialysis (Tx) were recently used in the treatment of intractable heart failure (HF). We examined the relation between the response of HF to Tx and the residual kidney functions. Tx was carried out in 17 patients (Pts) with HF who did not respond to aggressive medical treatment. Ten Pts (R) responded to Tx and 7 Pts (N) did not. Serum urea nitrogen (UN), creatinine (Cr), uric acid (UA), sodium (Na), potassium (K), and chloride (Cl) concentrations on admission and before Tx were not different between R and N. Urine UN, Cr, Na, K, and Cl on admission and before Tx were also not significantly different. Fractional sodium excretions (FENa), renal failure indices (RFI), and urine/plasma Cr ratios (U/P Cr) on admission were 2.0 +/- 1.6, 2.7 +/- 2.2, and 30.5 +/- 20.0 in R and 5.9 +/- 4.2, 8.2 +/- 6.0 and 11.5 +/- 3.8 in N. They were significantly different (p less than 0.05). However, these did not differ before and after Tx. These data show that FENa, RFI and U/P Cr might be useful indices in predicting the responsiveness of intractable HF to Tx.

Adult↗
PubMed1994

An increased rate of cell-free protein synthesis by condensing wheat-germ extract with ultrafiltration membranes.

Wheat-germ extract for cell-free protein synthesis was condensed with ultrafiltration membranes of which the molecular cut-off values were 10 kDa, 100 kDa, and 300 kDa. Reaction conditions of the cell-free system were optimized for the condensed extracts, which needed a higher concentration of creatine phosphate than the uncondensed one, probably due to the increased activity of degradation of ATP and GTP. By using the condensed extract and optimized reaction conditions, the rate of protein synthesis was increased 2- to 3-fold compared with using an uncondensed extract, and about 10-fold compared with conventional conditions. Condensation of the extract with the 300-kDa membrane showed the highest productivity, which was about 30 micrograms dihydrofolate reductase protein ml-1 h-1. The final amount of synthesized protein was one third of that of a continuous-flow cell-free (CFCF) system reported by Endo et al. [J. Biotechnol., 25, 221-230 (1992)] but the productivity was 5-fold higher than that obtained by the CFCF system.

Adenosine Triphosphate↗
PubMed1995

Preparation of casein phosphopeptides from casein micelles by ultrafiltration.

Casein phosphopeptides (CPPs), which inhibit the precipitation of calcium phosphate in the intestines, were prepared as CPP-calcium phosphate complexes from casein micelles by the ultrafiltration method. The prepared CPPs hardly contained any other peptides, so there was no need to treat with active carbon to remove the bitter peptides. The sum of alpha s1-CN-5P(f59-79) and beta-CN-4P(f1-25) comprised 60% of the CPP composition by an analysis of the elution pattern from a Q-Sepharose FF column. The content of alpha s1-CN-5P(f59-79), which has high retention ability for calcium phosphate, was the highest in the CPPs.

Animals↗
PubMed2004

Use of whey ultrafiltrate as a substrate for production of carotenoids by the yeast Rhodotorula rubra.

Carotenogenesis of the lactose-negative yeast Rhodotorula rubra GED5 was studied by cocultivation with Kluyveromyces lactis MP11 in whey ultrafiltrate (WU) (35, 50, and 70 g of lactose/L). Maximum yields of cell mass (24.3 g/L) and carotenoids (10.2 mg/L of culture fluid or 0.421 micro g/g of dry cells) were obtained by growing the microbial association in WU (50 g of lactose/L) in a fermentor with an airflow rate of 0.8 L/(L.min), agitation of 220 rpm, and temperature of 30 degrees C. The identified carotenoid pigments-beta-carotene, torulene, and torularhodin-reached maximum concentrations (133, 26.9, and 222.3 microg/g of dry cells, respectively) on d 5 for torulene and d 6 for beta-carotene and torularhodin.

Animals↗
PubMed2004

Cellulase retention and sugar removal by membrane ultrafiltration during lignocellulosic biomass hydrolysis.

Technologies suitable for the separation and reuse of cellulase enzymes during the enzymatic saccharification of pretreated corn stover are investigated to examine the economic and technical viability of processes that promote cellulase reuse while removing inhibitory reaction products such as glucose and cellobiose. The simplest and most suitable separation is a filter with relatively large pores on the order of 20-25 mm that retains residual corn stover solids while passing reaction products such as glucose and cellobiose to form a sugar stream for a variety of end uses. Such a simple separation is effective because cellulase remains bound to the residual solids. Ultrafiltration using 50-kDa polyethersulfone membranes to recover cellulase enzymes in solution was shown not to enhance further the saccharification rate or overall conversion. Instead, it appears that the necessary cellulase enzymes, including beta-glucosidase, are tightly bound to the substrate; when fresh corn stover is contacted with highly washed residual solids, without the addition of fresh enzymes, glucose is generated at a high rate. When filtration was applied multiple times, the concentration of inhibitory reaction products such as glucose and cellobiose was reduced from 70 to 10 g/L. However, an enhanced saccharification performance was not observed, most likely because the concentration of the inhibitory products remained too high. Further reduction in the product concentration was not investigated, because it would make the reaction unnecessarily complex and result in a product stream that is much too dilute to be useful. Finally, an economic analysis shows that reuse of cellulase can reduce glucose production costs, especially when the enzyme price is high. The most economic performance is shown to occur when the cellulase enzyme is reused and a small amount of fresh enzyme is added after each separation step to replace lost or deactivated enzyme.

Biomass↗
PubMed1987

[Centrifugal ultrafiltration method for determining the percent of free testosterone in serum].

Serum free testosterone (T) % in the follicular phase of 11 normal women, 11 normal men and 30 pregnant women of 5 to 39 weeks of gestation were determined by the centrifugal ultrafiltration method (CUF), which was performed at the centrifugation of 5 minutes, 1000 g and 37 degrees C, using the Amicon MPS-3 and YMT membrane. These conditions were shown to be appropriate for measuring the free T. There was a significant correlation between the percentage of free T due to the CUF and the equilibrium dialysis method (ED) (r = 0.88, p less than 0.01). Serum free T % and free T concentrations by the CUF method were, respectively, 2.89 +/- 0.09 (SE) % and 166.3 +/- 9.8 pg/ml in normal men, 1.76 +/- 0.09% and 9.4 +/- 0.7 pg/ml in non-pregnant women and 1.14 +/- 0.03%, 22.4 +/- 1.4 pg/ml in pregnant women. Serum free T % in non-pregnant women was significantly lower than in men (p less than 0.001) and higher than in pregnant women (p less than 0.001). In the CUF method the intra-assay CV was 4.9% in women, 6.0% in men and the inter-assay CV was 5.1% in women, 6.2% in men. The CUF method was more simple, rapid and accurate on the determination of the free T in serum than the ED method.

Centrifugation↗
PubMed1981

Interlaboratory investigation on the CEA assay (Roche) with column filtration, dialysis and ultrafiltration techniques.

An interlaboratory study on the reproducibility of the CEA (Roche) RIA Test was carried out. Four different plasma pools of approximately 2, 3, 6, and 12 micrograms/l CEA were tested over a period of 4 weeks with 4 different lots of reagents in order to determine the interassay variances. At the same time we compared the lately introduced column technique with the dialysis and ultrafiltration method. Best results were obtained with the column technique which also showed best reproducibility. Only 1.4% of samples showed deviations greater than 5% between the mean of CEA duplicates and single CEA values, and these were omitted from the evaluation. On the other hand about 15% of the corresponding dialysis results showed deviations greater than 5% and were excluded from the evaluation. The methods compared showed a good correlation with a coefficient of 0.96, but the average values for the CEA determination, using the columns technique were lower than those obtained from dialysis. Interassay variances were greater for the dialysis procedures, i.e. 1.88 +/- 0.81, 3.25 +/- 0.83, 5.81 +/- 1.09, and 11-91 +/- 1.23 compared with 1.77 +/- 0.54, 2.63 +/- 0.68, 4.89 +/- 0.79, and 11.16 +/- 1.23 for the column technique. There were no systematic changes of the CEA values over the period of 4 weeks, thus giving optimal conditions for a follow up of patients.

Carcinoembryonic Antigen↗
PubMed2006

Utilizing ultrafiltration to remove alkaline phosphatase from clinical analyzer water.

Alkaline phosphatase (ALP) conjugated to antibodies is often used in enzyme immunoassays (EIAs). These assays are notably sensitive to experimental conditions. A possible source of interference is bacterial ALP, which is released when bacterial contamination occurs in clinical analyzers. Preliminary experiments led to the selection of a detection kit, ALP source, and specific types of tubes for collecting water samples and performing assays. The release of ALP from various strains of bacteria identified in pure water was demonstrated (10-30 x 10(6) cfu/mL released 6-10 microU/microL). It was shown that ultrafiltration is totally efficient in removing ALP from water, while residual ALP activity (2.21 microU/microL after filtration of an ALP solution of 6.22 microU/microL) was observed after filtration using a 0.22-mum filter.

Alkaline Phosphatase↗
PubMed1987

The influence of free fatty acids on the free fraction of thyroid hormones in serum as estimated by ultrafiltration.

Thyroid hormones are displaced from their binding proteins in serum during nonthyroidal somatic illness, and FFA have been claimed to contribute. It seems mandatory to evaluate this effect using techniques for the measurements of serum free thyroid hormones in which serum remains undiluted. We measured the effect of 7 common human FFA on the free fraction of T4, T3 and rT3 in serum from healthy subjects using an ultrafiltration technique by which serum is diluted only minimally. In addition we measured the effect of oleic acid on the free fractions of the iodothyronines in pooled serum from healthy subjects and in pooled serum from patients with nonthyroidal illness. All FFA tested were able to displace both T4, T3 and rT3, but to a varying degree, arachidonic and linoleic acid being the most potent ones. A 20% increase in the free fractions of T4, T3 and rT3, respectively, was obtained by adding between 1.7-3.3 mmol/l, 1.3-4.6 mmol/l and 1.0-2.4 mmol/l of the different FFA. A serum pool obtained from patients with nonthyroidal somatic illness was more sensitive to oleic acid than a serum pool obtained from healthy subjects, since 2-3 times less oleic acid was necessary to induce a 20% increase in the free fractions of thyroid hormones. It is concluded that FFA are able to displace both T4, T3 and rT3 from their serum binding proteins in healthy subjects as well as in patients with nonthyroidal illness. However, serum from patients with nonthyroidal illness was more sensitive to the displacing activity of oleic acid than serum from healthy subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Cerebrovascular Disorders↗
PubMed2004

Effect of sodium balance and the combination of ultrafiltration profile during sodium profiling hemodialysis on the maintenance of the quality of dialysis and sodium and fluid balances.

Excessive sodium gain is a major hindrance of sodium profiling hemodialysis (HD) that offsets the benefit in reducing intradialytic hypotension-related discomforts (IHD). Patients who showed frequent IHD (>30% of the sessions; n = 11) were enrolled in a prospective study that consisted of two phases. In the phase 1 study, eight treatment modalities were evaluated: Conventional HD (control), sodium balance-positive step-down sodium profiling HD (PS), sodium balance-neutral step-down sodium profiling HD (NS), sodium balance-neutral alternating sodium profiling HD (NA) without ultrafiltration (UF) profile, and all those with UF profile (UF only, PS+U, NS+U, and NA+U). The incidences of "dialysis failure," defined as the occurrence of one or more of (1) session failure (discontinuation of session <75% of planned time), (2) UF failure (%UF achieved <70%), and (3) delivery failure (Kt/V <1.1), were 48.5, 21.2, 42.4, 39.4, 45.5, 18.2, 21.2, and 18.2% in control, PS, NS, NA, UF only, PS+U, NS+U, and NA+U, respectively. Four treatments, PS, PS+U, NS+U, and NA+U, reduced the incidence of dialysis failure significantly as compared with control (P < 0.05) and were evaluated in the phase 2 study, a randomized controlled 6-wk crossover study. Parameters were measured in the steady state after a 6-wk maintenance of each treatment. Diffusive sodium gain (DeltaNa) was significantly increased with sodium balance-positive profiles with or without UF profile, PS and PS+U (PS 1.9 +/- 1.1, PS+U 1.7 +/- 1.0 mEq/L; both P < 0.05 to control -0.1 +/- 0.2, NS+U 0.5 +/- 0.4, NA+U 0.4 +/- 0.2 mEq/L). They also increased the interdialytic weight gain (PS 3.8 +/- 0.6, PS+U 4.0 +/- 0.6 kg; both P < 0.05 to control 2.7 +/- 0.6, NS+U 3.3 +/- 0.6 kg; both P = NS to NA+U 3.5 +/- 0.6 kg). Predialysis weight and the required amount of UF also increased significantly with these sodium balance-positive profiles. Although the absolute amount of UF was larger with PS and PS+U, %UF achieved targeting dry weight was higher with sodium balance-neutral profiles with UF profiles, NS+U and NA+U (NS+U 92.7 +/- 3.8, NA+U 93.7 +/- 6.8%; both P < 0.05 to control 72.6 +/- 14.0, PS 88.3 +/- 6.6, PS+U 88.2 +/- 8.2%). Postdialysis weight was closest to dry weight with these treatments showing Delta (postdialysis weight - dry weight) of 0.3 +/- 0.1 and 0.3 +/- 0.2 kg in NS+U and NA+U (both P < 0.05 to control 1.0 +/- 0.6 kg; both P = NS to PS 0.5 +/- 0.3, PS+U 0.5 +/- 0.4 kg). Incidence of excessive weight gain and subjective discomforts during the interdialytic period increased significantly with PS. In conclusion, continuous use of sodium balance-positive sodium profiles resulted in an undesirable steady state with sodium and fluid expansion offsetting their hemodynamic benefit. Sodium balance-neutral sodium profiles in combination with UF profile were associated with less sodium and weight gains, better UF performance with postdialysis weight closest to dry weight, and fewer interdialytic problems with the equivalent hemodynamic benefit. Therefore, it is proposed that sodium balance-neutral sodium profiling HD with UF profile is a better choice, ensuring the dialysis of quality without sodium gain-related complications.

Body Weight↗
PubMed2004

Superiority of icodextrin compared with 4.25% dextrose for peritoneal ultrafiltration.

Several clinical observations suggest the superiority of icodextrin compared with 4.25% dextrose in optimizing peritoneal ultrafiltration (UF), but no rigorous controlled evaluation has hitherto been performed. For comparing icodextrin and 4.25% dextrose during the long dwell of automated peritoneal dialysis, a multicenter, randomized, double-blind trial was conducted in 92 patients (control, 45; icodextrin, 47) with 4-h dialysate to plasma ratio creatinine >0.70 and D/D(0) glucose <0.34. Long-dwell net UF and the UF efficiency ratio (net UF volume per gram of dialysate carbohydrate absorbed) were determined at baseline, week 1, and week 2. The control and treatment groups were comparable at baseline (all patients using 4.25% dextrose for the long dwell) with regard to mean (+/-SEM) net UF (201.7 +/- 103.1 versus 141.6 +/- 75.4 ml, respectively; P = 0.637) and the percentage of patients with negative net UF (control, 37.8%; treatment, 42.6%; P = 0.641). During the study period, net UF was unchanged from baseline in the control group but increased significantly (P < 0.001) in the icodextrin group from 141.6 +/- 75.4 to 505.8 +/- 46.8 ml at week 1 and 540.2 +/- 46.8 ml at week 2. In the icodextrin group, the incidence of negative net UF was significantly lower (P < 0.0001) than in the control group. Findings were similar for UF efficiency ratio. Rash was reported significantly more often in the icodextrin group. This study showed that in high-average and high transporters, icodextrin is superior to 4.25% dextrose for long-dwell fluid and solute removal.

Dialysis Solutions↗
PubMed1987

Determination by ultrafiltration of the fraction of unbound estradiol and its variation in peritoneal fluid during the menstrual cycle.

An ultrafiltration method employing a Centrifree filter for determining the unbound fraction of estradiol was studied. Centrifugation was performed under conditions similar to those in vivo. Good correlation was recognized between this method and the equilibrium dialysis. This method was employed to determine the unbound fraction of estradiol in the serum and the peritoneal fluid of 26 infertility patients classified according to their menstrual dates. The total estradiol and progesterone contents in the peritoneal fluid were high after ovulation. There was no significant difference in the percentage of unbound estradiol in the serum among various groups. In the peritoneal fluid, however, the percentage of unbound estradiol for the day 12-14 patients was 4.5 +/- 0.2% in contrast with 3.8 +/- 0.4% for the day 15-18 group (p less than 0.05) and 3.5 +/- 0.1% (p less than 0.05) for the day 19-28 group. Moreover, the fraction (4.5%) of unbound estradiol in the peritoneal fluid of a patient with luteinized unruptured follicle (LUF) syndrome was comparable with that of patients in the follicular phase. The difference between the percentage of unbound estradiol in the peritoneal fluid before and after ovulation is considered to be due to the transudation of follicular estradiol in the follicular phase and the exudation of estradiol from the corpus luteum into the peritoneal cavity in the luteal phase.

Ascitic Fluid↗
PubMed1977

Proteins retained with hyaluronic acid during ultrafiltration of synovial fluid.

The identity of the proteins associated with hyaluronic acid after ultrafiltration of bovine synovial fluid was examined. With discontinuous filtration, alpha2 macro- and IgM globulins were retained in hyaluronic complex both from synovial fluid and from a similar mixture of hyaluronic acid and serum. With continuous filtration and stirring to prevent formation of gels, protein was retained with hyaluronic acid in similar proportions. This protein showed immunologic identity with serum albumin, but differed in amino acid composition. After comparison with results of gel filtration, it was concluded that the identity of the retained proteins can be determined by the concentration of hyaluronic acid without variation in other ionic conditions.

Albumins↗