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Ultrafiltration is an important step in isolation and purification of pullulan. Here a new formula for ultrafilter calculation is derived from experiments about the relationship between the ultrafiltrate rate and the concentration of pullulan solution. It can be used for calculating and designing of ultrafilter under defined production scale and its related technical parameters.
A new totally antithrombogenic continuous ultrafiltration system (ACUS), consisting of polyacrylonitrile-polyethyleneoxide (PAN-PEO) membrane and ionically heparin-bound catheter, tubing, and module header was designed and its performance was confirmed through animal experiments and clinical evaluation. Animal experiments revealed that persistent antithrombogenicity and maintained ultrafiltration without systemic heparinisation were observed only when the three major parts--i.e. (1) the catheter and tubing, (2) the header part of a haemofilter module, and (3) the fibre membrane--were all antithrombogenic and connected to each other without uneven structures. ACUS was clinically applied to 15 oliguric patients with various severe conditions. We found that one filter could function for approximately 26 h without systemic anticoagulation, even in the presence of low blood pressure, and that ACUS did not change platelet function. Thus, ACUS seems to be very suitable for the management of volume overload, especially in patients with severe circulatory problems or bleeding tendencies.
+Ultrafiltrated bovine milk proteins with whey protein/casein ratios 20/80, 60/40 and 97/3 were subjected to pancreatin hydrolysis, and the hydrolysates obtained were fractionated to high- and low-molecular weight (LMW) fractions by means of ultrafiltration. The preparations obtained were characterized according to routine physico-chemical indices, amino-nitrogen content, amino acids score, molecular weight distribution, and concentration of precipitating milk antigens. The capacity of LMW fractions for inducing oral anaphylactic sensitization in guinea pig and for changing its susceptibility to histamine LD50 was studied. The conclusion has been made that LMW preparations with whey/casein ratios 20/80 and 60/40 could be effectively used in specialized formulae intended for nutrition of allergic children and adults, nursing women, and also for enteral nutrition.
After 6 months of (recombinant human erythropoietin) rHuEPO treatment we recently observed an increased peritoneal ultrafiltration (UF) (Nephron 53: 91, 1989). The aim of the present study was to investigate the long term effect of subcutaneous (SC) on dialysis efficiency in CAPD. Fourteen patients (11 female, 3 male, mean age 42.6, range 18-65 years) with renal anemia (HCT less than 28%) took part in the study. rHuEPO was administered s.c. twice weekly in an initial dose of 50 U/kg body weight. This dose was increased by 25 U/kg body weight every 4 weeks till the target HKT of 35% had been achieved. After 12 months of mean time of treatment (range 8-14 months) hematocrits had increased from 23.3 +/- 3.2 (x +/- SD) to 36.6 +/- 5.3% (p less than 0.005). UF improved from 0.70 +/- 0.22 to 1.03 +/- 0.47 ml/min (4 hr dwell time, 1.5% glucose monohydrate) (p less than 0.03). Increased UF resulted in an augmented creatinine clearance (p less than 0.05). No changes were observed in serum chemistries, body weight, pulse rate or cardiothoracic index. The observed increase in peritoneal ultrafiltration might be due to augmented mesenteric perfusion resulting from improved cardiac function. The sustained increase in UF after rHuEPO-induced correction of renal anemia may improve the fluid balance on CAPD patients.
Previous publications have suggested that peritoneal capillary blood flow and filtration pressure equilibrium may limit ultrafiltration rates with very hypertonic exchanges. Rats were treated with pentoxifylline, which decreases blood viscosity by increasing red blood cell deformability. Decreases in blood viscosity should reduce microcirculatory resistance and increase effective capillary flow. Transport studies were performed after 2, 4, and 8 weeks of therapy with peritoneal dialysis solutions containing 15 grams % dextrose and using 30-min cycles. Even though rats ingested near the maximum recommended dose of pentoxifylline (20 mg/kg) significant changes in blood viscosity and shear stress were not detected compared to controls. Also, there were no significant differences in clearances of urea and phosphorus, glucose absorption, protein losses, and net ultrafiltration compared to controls.
Three patients on peritoneal dialysis (two on continuous ambulatory and one on intermittent) with severe ultrafiltration failure were treated with 2 capsules of Lecithin three times a day (containing of 1.08 g of phosphatidylcholine). Their ultrafiltration improved significantly to the point that their edema improved and were able to continue on peritoneal dialysis with fewer daily hypertonic exchange.
In 27 patients undergoing continuous pump-driven hemofiltration during intensive care, a new balancing device was used to control transmembrane pressure difference, and thus ultrafiltration rate, by means of an elastic reservoir and an infusion pump. The simultaneous infusion of substitution fluid by a second pump working independently of the former provided exactly and automatically the intended fluid balance. In only 0.7% of the total hemofiltration time (5519 h) could the preset ultrafiltration rate not be achieved. The simple components and installation of this device recommend its application in every intensive care unit that uses continuous arteriovenous or continuous pump-driven hemofiltration, relieving the staff and reducing unwanted and unnoticed deviations of intravascular volume and fluid balance.
The authors describe the use of isolated ultrafiltration (IUF) in 16 patients with massive refractory edema associated with the nephrotic syndrome of varying etiology. IUF appeared efficacious in 11 patients and permitted the reduction of the patients' body weight by 9.8 +/- 2.6 kg on the average (maximally by 23 kg) at the expense of the removal of protein-free ultrafiltrate. The removal of the protein-free liquid was not accompanied by any material changes in the electrolyte content in serum. It did not produce alterations in the circulating blood volume or subsequent reduction of diuresis, making IUF more physiological procedure as compared to massive treatment with diuretics. IUF turned out more effective in patients with the hypervolemic pattern of the nephrotic syndrome.
A simple HPLC procedure for the quantitation of AICA-riboside (Z) and its 5-monophosphate metabolite (ZMP) in ultrafiltrates of plasma and lysed whole blood, respectively, has been developed. Samples of plasma or previously frozen whole blood were subjected to ultrafiltration by centrifuging for 30 minutes in an Amicon Centrifree Micropartition cartridge and the filtrates analyzed directly by HPLC. Compound Z was quantitated by UV detection at 270 nm following isocratic reverse-phase chromatography on a C18 column and ZMP following isocratic chromatography on an anion exchange (SAX) column. The limits of sensitivity for Z in plasma and ZMP in blood were 0.1 and 2.5 micrograms/ml, respectively. Neither compound was protein bound and recoveries were greater than 95%. The intra- and inter-day coefficients of variation were less than 5%. The method has been used to evaluate the pharmacokinetics of Z and ZMP in man. The procedure should be applicable to the quantitation of certain other nucleosides and nucleotides in biological media.
The authors provide an experience with a novel alternative of ultrafiltration hemoconcentration applied to 26 patients in surgery involving extracorporeal circulation. The advantages of the new procedure are maintenance of higher colloid-osmotic pressure, prevention of hyperglycemia, lower body elimination of biologically active compounds and drugs than those observed during the routine procedure of ultrafiltration comprising extracorporeal circulation.
Serum antibody reactivity to squamous cell carcinoma of the head and neck (SCCHN) was evaluated in 41 autologous serum-tumor cell line combinations using the protein A hemadsorption assay. Autologous antibody reactivity (median titer of 1:4) was detected in sera from 24 of the patients tested. In 10 cases autologous antibody reactivity could be detected only in undiluted serum precluding further analysis. Analysis of higher titer sera from one patient revealed antibodies that define an antigen expressed on autologous tumor cells cultured from both the primary tumor (UM-SCC-17A) and from a metastasis (UM-SCC-17B). Absorption analysis showed that this antigen was also expressed on 6 of 10 allogeneic SCCHN cell lines but not on autologous fibroblasts or on allogeneic melanoma cell lines. Due to the low titer of autologous antibody reactivity in most sera, we sought to determine if dissociation of immune complexes through acidification and ultrafiltration of serum might enhance detectable antibody reactivity as has been done in previous studies in melanoma. Twelve serum samples from eight patients were subjected to acid dissociation and ultrafiltration (AD-U). Only six of the untreated sera had detectable antibody reactivity against the autologous SCCHN cell line whereas following AD-U all 12 sera had enhanced IgG reactivity against autologous SCCHN. Specificity analysis of one serum sample after dissociation revealed that the antibody detected an antigen common to SCCHN cell lines as well as melanoma, glioma, renal, and colon carcinoma cell lines. Circulating immune complexes may provide a reservoir of antibody with potential diagnostic and therapeutic applications.
Forty cardiopulmonary bypass patients were randomized into two matchable groups, an ultrafiltration and an control group. We have concluded that change of plasma colloid oncotic pressure may be a more sensitive parameter of monitoring the effect of ultrafiltration during cardiopulmonary bypass.
The highly permeable synthetic polyacrylonitrile (PAN) membrane (Filtral; Hospal, Basle) is regarded as biocompatible for its slight complement activation and leucocyte sequestration. The low C3a and C5a concentrations during PAN dialysis may be due to a lack of complement activation potential of this polymer, but also to elimination of activated complement components by the dialyser through adsorption and/or ultrafiltration (mol wt of C3a and C4a 9000 daltons; of C5a 11,000 daltons). Comparing arteriovenous differences throughout the study, higher concentrations of C3a (+23%; n.s.) and C5a (+80%; P less than 0.05) were measured in the efferent blood lines, suggesting a slight complement activation by the alternate pathway. A significantly lower C4a concentration in the efferent blood lines (-30%, P less than 0.05) indicates an elimination within the dialyser. Significantly higher arteriovenous concentration differences at the beginning of dialysis and increasing sieving coefficients suggest elimination by adsorption, mainly in the first 20 min of haemodialysis. The continuous decrease of C3a and C4a plasma concentrations in the afferent blood line suggests transport across the membrane and removal by the dialysate. Accordingly, measurable amounts of these complement components were detected in ultrafiltrate.
The amount of fluid withdrawn by ultrafiltration in a dialysis session plays an important role in regulating the acid-base status of patients. It has been previously demonstrated that an interdialytic weight gain of 3 kilograms requires the removal of 3 liters, mostly of extracellular fluid, which may contain 60-70 mMols of bicarbonate. Such losses require an increase in the buffer mass transfer to achieve a good buffer balance. The importance of interdialytic weight gain (IWG) on acid-base status was evaluated in two significantly different periods. In the period where the IWG was lower, predialytic pH and HCO3 were significantly higher than in the alternate period. Since dialysis schedule, dialysate buffer, daily protein intake and given medications did not differ during the two periods, we conclude that a reduced ultrafiltration due to less weight gain betters predialytic acid-base status.
A possibility of concentration and purification of culture fluid of Escherichia coli by the ultrafiltration technique using Soviet cellulose acetate membranes were studied. It is established that cellulose acetate membranes may be used for purification from low molecular weight protein and concentration of preliminarily purified culture fluid of Escherichia coli. Membranes YAM-300 are most preferable. At the temperature of 18 degrees C, pressure 0.16-0.24 MPa and 20-fold concentration the yield of the enzyme at the ultrafiltration stage was 84.5%.
High flux polysulphone (PS600, Fresenius) is a highly biocompatible membrane, but the high ultrafiltration (UF) capacity limits its clinical applications. In the present study a new PS (PS400) with an UF coefficient in the range of cuprophan (CU) but a biocompatibility like high flux PS was evaluated. Dialysis efficiency with PS400 was compared to dialyzers with the same surface, at similar blood flows. Overall extraction of UV-absorbing compounds was higher with PS400 (P less than 0.01). The extraction of the individual compounds, hippuric acid and parahydroxy-hippuric acid was also higher for PS400 (P less than 0.01 resp. less than 0.05). The fall in white blood cells after 15 min. of dialysis was from 6.5 +/- 1.5 to 1.7 +/- 0.6 for CU (-83%), and from 8.6 +/- 1.7 to only 7.4 +/- 1.7 x 10(3) cells/mm3 (-14%) for PS400 (P less than 0.01 versus CU). Ultrafiltration characteristics were similar for both dialyzers.
Cardiovascular hemodynamics were studied noninvasively before, during and after hemodialysis with ultrafiltration in 18 patients on chronic hemodialysis. The cardiac output (CO) was determined by a continuous wave Doppler method. Overall, no major CO changes were seen (7.8 +/- 0.6 l/min post- versus 7.4 +/- 0.5 l/min pre-dialysis). Mean blood pressure rose slightly but significantly from 103 +/- 4 mmHg before to 113 +/- 3 mmHg after hemodialysis (p less than 0.01). Important interindividual differences in the intradialytic evolution of CO were observed. In patients with previous myocardial infarction or dilated cardiomyopathy (n = 12), CO rose significantly from 7.3 +/- 0.7 l/min before to 8.4 +/- 0.6 l/min after hemodialysis (p less than 0.05), while in patients without manifest myocardial disease (n = 6) CO decreased from 7.5 +/- 0.7 l/min to 6.6 +/- 0.9 l/min (NS). Comparison of the evolution of CO in both groups by variance analysis revealed a significant difference (p less than 0.01). It is concluded that, in response to hemodialysis with ultrafiltration, CO probably will increase in patients with myocardial infarction or congestive cardiomyopathy, but probably will decrease in patients without.
Venous plasma middle molecule compounds (MMC) were determined in 63 cardiosurgical patients, operated on for acquired heart diseases or coronary disease, with assisted circulation (AC) and with or without blood ultrafiltration (BUF). Intraoperative MMC level was superior to that of normal donors, and tended to decrease during AC, while BUF had basically no effect on MMC content, in spite of the latter's withdrawal with the ultrafiltrate.