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PubMed1977

Hemofiltration: treatment of renal failure by ultrafiltration and substitution.

Hemofiltration, in contrast to hemodialysis or peritoneal dialysis, eliminates toxic substances accumulated in uremia by a process that is independent of molecular weight. By means of a special device, the ultrafiltrate of blood is replaced, up to the desired amount, by a modified Ringer's lactate solution. The application of this new method results in better control of severe hypertension, and controls calcium phosphate and lipid metabolism in a more physiologic manner than dialysis does, without additional drug therapy being necessary. Smaller amounts of fluid and a simplification of devices improve hygienic conditions and patient mobility.

Blood Pressure↗
PubMed1979

In vitro characterization of the RP-6 dialyzer: co-current and counter-current clearance as a function of ultrafiltration.

Analytical and graphical techniques are described for presenting clearance data as a function of ultrafiltration; thus for the first time comparison of clearance values between dialyzers can be made unambiguously. This simple method uses a hand calculator to determine three coefficients. Clearance has been shown to be accurately described by the equation C = alpha 1 + alpha 2 Qv + alpha 3 (1/QBi). This formula permits construction of easily read families of curves which can predict clearance values under most clinical situations. The RP-6 dialyzer is characterized by these methods for clearance of urea, glucose and vitamin B 12 for counter-current and co-current modes.

Blood Flow Velocity↗
PubMedDate not supplied

Hypoosmotic dialysis and ultrafiltration technique for preparation of mammalian hemoglobin: a comparison of three species.

Dialysis of human, bovine, and ovine red blood cells using a hypotonic solution and a commercial kidney dialysis unit, followed by ultrafiltration through 0.1 micron pore hollow-fibers provides an easily managed method for isolation of lipid-free hemoglobin (LFHB). High performance liquid chromatography (HPLC) analysis of hemoglobin indicated 99% protein purity. SDS polyacrylamide gel electrophoresis analysis demonstrated that LFHB migrates as a single band. Processing one-half liter of packed red blood cells requires approximately 10 hours and resulting in an average of 93% hemoglobin recovery.

Animals↗
PubMed1981

Ultrafiltration during open-heart surgery in chronic renal failure.

Ultrafiltration at the end of cardiopulmonary bypass is an important improvement in major cardiac surgery in patients with chronic renal failure and also in dialysis-dependent patients. It has many advantages over pre- and postoperative haemodialysis or peritoneal dialysis. The method, employing disposable equipment, is easy to use, does not prolong total pump time, as it is of short duration, and restores at the end of operation normovolaemia and haematocrit values.

Adult↗
PubMed2005

Sieving effect of heat-denatured milk proteins during ultrafiltration of skim milk. I. The preliminary approach.

The effect of heat treatment of skim milk on the ultrafiltration process was examined. The change in permeate collection rate was explained as a function of heat-induced modifications of the milk protein system. It is suggested that there was a sieving effect which contributed to the acceleration of permeate flow-down during membrane filtration. It is thought that this resulted from formation of complex structures between heat-denatured whey proteins and casein micelles.

Animals↗
PubMed1985

Removal of penicillin G from contaminated milk by ultrafiltration.

Penicillin G purposedly added to whole raw milk at concentrations from .05 to .20 IU/ml was removed to undetectable levels by a combination of ultrafiltrations and permeate washes. After penicillin removal, whole milk 3:1 vol/vol concentrated retentates were reconstituted to milk with antibiotic-free permeate with little change in composition and with very good to excellent flavor. Washing 3:1 vol/vol concentrated retentates from penicillin-contaminated milks with water also removed penicillin to an undetectable level but changed the composition of product, which displayed a flat flavor.

Animals↗
PubMed1986

Influence of milk ultrafiltration on bacteriophages of lactic acid bacteria.

Bacteriophages added to whole milk were partially concentrated during ultrafiltration. At 4:1 retentate, phage had concentrated 2.4:1. Thermal destruction at 54 degrees C followed first order kinetics up to 6% protein, whereafter it deviated. When allowed to grow in retentate in the presence of appropriate host, 3.5 generations of phage appeared after 12 h at 22 degrees C compared with four generations in skim milk. In the presence of phage, lactic acid bacteria population increased to only 10(7) cfu/ml compared with 3 X 10(9) in their absence. Retentate starter prepared in the presence of phage was as active as skim milk starter prepared in the presence of phage.

Animals↗
PubMed1997

[Measurement of relative plasma volume and plasma refilling rate during ultrafiltration of hemodialysis by measuring apparatus of plasma colloidal osmotic pressure].

BACKGROUND: The objective of this study is the prevention of unexpected hypotension during hemodialysis caused by unsuitable filtration rate. METHODS: The plasma colloidal osmotic pressure (COP) was measured continuously during ultra-filtration, and relative plasma volume (%PV) and plasma refilling rate (PRR) were calculated during 12 ECUMs and one dialysis on twelve patients in early stage of chronic renal failure. Values of %PV and PRR calculated from COP were drawn in graphic curves, and analysed to obtain characteristic pattern. Minimum value of %PV (%PV min), maximum value of PRR (PRRmax) and time for PRR to decrease to 95% (95% PVt) on the curves were documented simultaneously. RESULTS: At the initial stage of %PV curve, obvious fall was observed on 6 of 13 estimation (initial fall of %PV). On the contrary at the initial stage of PRR curve, obvious rise was observed on 5 estimation (initial rise of PRR). A close relationship was indicated between the two phenomenons. In 6 cases with initial fall of %PV and in 5 cases with initial rise of PRR body weight, PRRmax and 95%PVt were lower than another cases without it. The ultra-infiltration velocity was estimated to be relatively high in these groups. In these 8 cases, filtrated water volume was judged as adequate clinically. In 4 of 5 cases without final fall of PRR, it was judged as inadequate and needed to evacuate more 0.9 to 3.0 kg (average of 1.8 +/- 1.07) of water from the patients. CONCLUSIONS: From the above, we concluded that our method is useful for deciding suitable velocity of ultrafiltration and dry weight in hemodialysis therapy.)

Adult↗
PubMedDate not supplied

[Permeability of acetylcellulose ultrafiltration membranes with regard to biologically active substances].

The permeability of standard Soviet ultrafiltration membranes prepared from cellulose acetates was investigated with respect to biologically active substances (hemoglobin, trypsin, ribonuclease, vitamin B12, hydroxytetracycline) and inorganic salt (KH2PO4). The arrest of a substance by a membrane of a certain structure depended primarily on the size of the substance macromolecule in the solution. The filtration rate was related to the membrane type, pressure gradient and composition of the filtered solution. Potential use of the tested membranes is described.

Cellulose↗
PubMedDate not supplied

Tranexamic acid increases peritoneal ultrafiltration volume in patients on CAPD.

OBJECTIVE: The preservation of ultrafiltration (UF) capacity is crucial to maintaining long-term continuous ambulatory peritoneal dialysis (CAPD).The aim of the present study was to investigate whether the antiplasmin agent tranexamic acid (TNA) increases UF volume in CAPD patients. PATIENTS AND METHODS: Fifteen patients on CAPD, 5 with UF loss and 10 without UF loss, were recruited for the study. The effect of TNA was evaluated with respect to changes in UF volume, peritoneal permeability, peritoneal clearance, bradykinin (BK), and tissue plasminogen activator (tPA) concentration. SETTING: Dialysis unit of the Saiseikai Central Hospital. RESULTS: In patients with UF loss, 2 weeks of treatment with oral TNA produced a significant increase in UF volume in all subjects (5/5).TNA also produced a significant increase in peritoneal clearances of urea and creatinine (Cr). However, the peritoneal equilibration test (PET) revealed that TNA had no effect on dialysate/plasma (D/P) Cr, Kt/V, or the protein catabolic rate (PCR).TNA also had no effect on net glucose reabsorption. In contrast, significant decreases in BK and blood tPA concentrations in response to TNA treatment were noted. BK concentration in drainage fluid was also reduced. In the case of patients without UF loss,TNA produced an increase in UF volume in 70% (7/10). However, no differences were found in blood and drainage BK and tPA concentrations between theTNA treatment and nontreatment periods in these patients. A comparison of basal BK and tPA concentration showed that there were no differences in these parameters between patients with UF loss and those without loss of UF. Furthermore,TNA given intraperitoneally to a patient also produced a marked increase in UF volume. CONCLUSION: The present study suggests thatTNA enhances UF volume in patients both with and without UF loss. SinceTNA did not affect peritoneal permeability and glucose reabsorption, the mechanism by which TNA exerts an enhancing action on UF is largely unknown. We speculate that it may be associated with suppression of the BK and/or tPA system, at least in patients with UF loss.

Absorption↗
PubMed1976

[Anaerobic serum ultrafiltration--a new method for determination of protein-binding rates of drugs under physiological conditions (author's transl)].

Only the free and not the protein-bound fraction of a drug shows pharmacologic activity. Therefore the rates of drug-binding to serum proteins are of great importance for clinical and pharmacological purposes. A basis prerequisite for accurate measurements are experimental designs giving the possibility of keeping the most important factors influencing the protein-binding rate within physiological ranges. In vivo these factors are, among others, the concentration of albumin, the absorption of different exogenous and endogenous substances to albumin, the type and the amount of ions present, the total ionic strength, the pH-value and hence the pCO2 as well as the temperature. An experimental set-up was described giving the possibility of keeping all these factors absolutely constant under in vivo conditions by means of a newly developed and simply to handle ultrafiltration device. From withdrawing the blood sample from the vein to the complete separation of the protein-bound fraction the blood sample can be processed under strictly anaerobic conditions (to prevent loss of CO2!). Compared to common methods generally used for the determination of protein-binding rates, such as equilibrium dialysis, column chromatography and ultracentrifugation, this new procedure saves a considerable amount of time. Within 1 h up to 8 samples can be processed in a single device. Besides short filtration times there is no need for any additional sample preparation such as buffering or adding antibacterial substances, etc.

Blood Proteins↗
PubMed1999

[Application of modified ultrafiltration to cardiac surgery in adults].

Modified Ultrafiltration (MUF) was developed for blood concentration and reduction of postoperative edema in cardiac surgery in children. Its beneficial effects on postoperative hemodynamics have been reported. We applied MUF to cardiac surgery in adults and evaluated its usefulness. Between August, 1995 and April, 1997, MUF was performed in 41 adult patients. MUF was carried out immediately after the cessation of cardiopulmonary bypass. The mean fluid volume removed was 1,135.9 +/- 274.1 ml. The patient's haematocrit significantly increased from 23.2 +/- 2.6% to 26.9 +/- 3.2% (p < 0.0001). The dose of inotropes administered was maintained constant during MUF, and no changes were observed in CVP and the heart rate. However, the systolic blood pressure increased from 99.5 +/- 14.7 to 113.2 +/- 16.2 mmHg (p < 0.0001) and cardiac index from 4.2 +/- 0.9 to 4.9 +/- 1.3 l/min/m2 (p = 0.0006). It was suggested that MUF was an useful technique of haemoconcentration and appeared to have beneficial effects on postoperative hemodynamics in adult cardiac surgery.

Adult↗
PubMed2000

Membrane distillation of human plasma ultrafiltrate and its theoretical applications to haemodialysis techniques.

Membrane Distillation (MD) is a technique that allows the extraction of water from aqueous solutions. The basic principle is that vapour, but not liquid water, can pass through hydrophobic micro-porous membranes, along a temperature gradient, with consequent separation of water from solutes. In this study we evaluated the possibility to utilise MD to extract water from Plasma Ultrafiltrate (PU) of patients with Chronic Renal Failure (CRF). The experiments were carried out in vitro by a hydro-phobic polypropylene hollow-fibre distillation module; PU was obtained by a CRF patient utilising a high permeability polisulphone membrane. The results show that water can be extracted by MD from PU of CRF subjects at a constant rate and that none of the substances analysed in PU was able to pass through the polypropilene membrane. In the future MD could integrate extra-corporeal blood purification techniques allowing the re-utilisation of plasmatic water thus ameliorating the treatment of uraemia.

Hemodiafiltration↗
PubMed2000

Plasma sample preparation by ultrafiltration for FTIR analysis.

Total body water (TBW) may be significantly altered with disease. Isotope dilution techniques, considered to be the "gold standard" methods for measuring TBW, are expensive, time consuming and require considerable expertise, especially during the sample preparatory phase. In this study, a new method, ultrafiltration (UF), was hypothesised to be an efficient alternative to vacuum sublimation (VS) in the preparation of plasma samples for Fourier Transform Infra Red (FTIR) determination of TBW. Deuterium Oxide (D2O) concentrations were prepared in human plasma and subjected to both techniques. FTIR analysis was carried out on the resulting VS and UF solutions and on D2O concentrations in distilled water. The resulting absorbance values were then statistically compared. Urea concentrations prepared in D2O-containing plasma were also compared to "blank" plasma to investigate the effect of high plasma urea concentration on the resulting H2O/D2O mixture obtained during UF Paired t-tests showed that the VS plasma samples (p=0.003), but not the UF samples (p=0.9), were significantly different to D2O standards prepared in distilled water. While there was no evidence of an effect of urea on UF at low (0.4 g/L) D2O concentration, a marginal (p=0.04) effect occurred at a higher (1.6 g/L) D2O level. Throughput of samples was much more efficient with the UF technique. These findings indicate that the new UF method is an accurate, more efficient method of plasma sample preparation than the VS method in the FTIR determination of TBW.

Blood Chemical Analysis↗
PubMed2001

[Efficacy of modified ultrafiltration in reoperation for valvular disease].

We evaluated the efficacy of modified ultrafiltration (MUF) in reoperation for valvular disease. Fourteen patients were divide into two groups consisting of a control group (n = 6) and a MUF group (n = 8). MUF was carried out for fifteen minutes immediately after the completion of cardiopulmonary bypass. The blood flow through the ultrafilter was 300 ml/min and about 1,200 ml of water was removed. The hematocrit elevated significantly from 25% to 31% in the MUF group (p < 0.05). The percentage of the increase in body weight after the operation in the MUF group was significantly less than that in the control group (3.3 +/- 3.1% vs 8.3 +/- 4.3%, p < 0.05). The PaO2/FIO2 after the operation in the MUF group was significantly higher than that in the control group (376 +/- 125 mmHg vs 242 +/- 79 mmHg, p < 0.05). The duration of mechanical ventilation in the MUF group was significantly less than that in the control group (1.1 +/- 1.1 days vs 5.3 +/- 3.3 days, p < 0.05). In conclusion, MUF is useful to hemoconcentrate, reduce postoperative body weight gain and promote early recovery of pulmonary function in reoperation for valvular disease.

Aged↗
PubMed2001

[Ultrafiltration of micropolluted water in combination with coagulation and PAC process].

The experiments of ultrafiltration of Huangpu River water with coagulation and powered activated carbon (PAC) combinations was evaluated. The results showed that coagulation and PAC pretreatment effectively remove dissolved organic matters (DOM), of which coagulation removes high molecular weight (MW) DOM and PAC removes low MW DOM. Coagulation and PAC are effective treatment for removing Trihalomethane Formation Potential (THMFP). In terms of low MW THMEP, coagulation removes poorly and PAC removes effectively. The results also showed that addition of coagulant and PAC reduce cake resistance greatly. At coagulant dosage 4 mg/L (as Al), cake resistance was minimized.

Charcoal↗
PubMed2002

Development of an ultrahigh-temperature process for the enzymatic hydrolysis of lactose. III. Utilization of two thermostable beta-glycosidases in a continuous ultrafiltration membrane reactor and galacto-oligosaccharide formation under steady-state conditions.

Hydrolysis of lactose by hyperthermophilic beta-glycosidases from the archaea Sulfolobus solfataricus (SsbetaGly) and Pyrococcus furiosus (CelB) was carried out at 70 degrees C in a continuous stirred-tank reactor (CSTR) coupled to a 10-kDa cross-flow ultrafiltration module to recycle the enzyme. Recirculation rates of > or =1 min(-1), reaction of proteins with reducing sugars, and enzyme adsorption onto the membrane are major "operational" factors of enzyme inactivation in the CSTR. They cause the half-life times of SsbetaGly and CelB to be reduced two- and eight-fold, respectively, the average value for both enzymes now being approximately 5 to 7 days. Using lactose at initial concentrations of 45 and 170 g/L, the CSTR was operated at a constant conversion level of approximately 80% for more than 2 weeks without the occurrence of microbial contamination. The productivities for the SsbetaGly-catalyzed conversion of lactose were determined at different dilution rates and initial substrate concentrations, and exceed by a factor of < or =2 those observed with CelB under otherwise identical conditions. This difference reflects the approximately eight-fold stronger product inhibition of CelB by D-glucose. While the maximum total galacto-oligosaccharide production (90-100 mM) at 170 g/L lactose in the CSTR was not different from that in the batch reactor (CelB) or was greater by approximately 25% (SsbetaGly), continuous and batchwise reactions with both enzymes differed markedly with regard to relative proportions of the individual saccharide components present at 80% substrate conversion. The CSTR yielded an up to four-fold greater ratio of disaccharides to trisaccharides concomitant with a 5- to 30-fold larger relative proportion of beta-D-Galp-(1-->3)-D-Glc in the product mixture. The results show that apart from continuous hydrolysis of lactose at 70 degrees C, a CSTR charged with SsbetaGly or CelB and operated at steady-state conditions could be a useful reaction system for the production of galacto-oligosaccharides in which composition is narrower and more easily programmable, in terms of the individual components contained, as compared to the batchwise reaction.

Bioreactors↗