Ultrafiltration dialyzers

Dialysis, kidney, 15 844-845 Dialysis membrane, hydraulic permeability/ultrafiltration coefficient of, 26 818-819 Dialyzer model, 26 817 Dialyzers... 

Micelle solutions of PlPAAm-Ci8H35 was prepared by direct dissolution of the polymer in cold water (4°C) due to its good water solubility [23]. Each solution of PIPAAm-PSt, PlPAAm-PBMA, and PIPAAm-PLA was prepared by dissolving each copolymer in DMF, A-ethylacetamide, and DMAc, respectively. The solutions were put into a dialysis bag (MWCO = 13,000) and dialyzed against distilled water at 10°C, 20°C, and 4°C, respectively, for 24 hours. The micelles were purified with ultrafiltration membrane of 200,000 molecular weight cut off at 4°C. The aqueous solution was lyophilized to leave a white powder of micelles. 

For all but the recombinant Alg A, extracellular enzymes were obtained from medium concentrated by ultrafiltration. For the E. chrvsanthemi enzymes, a mixture precipitated between 60 and 90% saturated ammonium sulfate was fractionated into individual activities by chromatofocusing. Enzymes from Lachnospira multiparus (strain D15d) and Clostridium populeti cultures wee analyzed directly in concentrated and dialyzed medium. The Alg A enzyme was expressed in E. coli HBlOl transformed with plasmid pAL-A3 (Brown, et al.. University of Florida, unpublished) from the periplasmic fraction. 

Combine fractions with A280 > 0.4, dialyze against the 100-fold volume PBS for at least 2 h, and centrifuge with 2000 x g for 20 min. If necessary, concentrate the dialysate by ultrafiltration. 

After the mild-hydrolysis step at 70°, the sialic acids liberated are removed from the sample by dialysis or ultrafiltration at 2°, and the macromolecular material is rehydrolyzed, using, however, the stronger acidic conditions of 0.1 M acid. The dialysis time ranges between 6 and 24 h, depending on the volume and viscosity of the hydrolysis mixture. Therefore, the optimum dialysis time should be evaluated by determinations of sialic acid in the eluate, or by addition of a trace of radioactive Nen5Ac. The dialyzates, or filtrates, are combined, and processed as will be described. By using this procedure, the overall yield of purified sialic acids is 70-80%, and the loss of O-acetyl groups107 is 40%. 

Dialyze pooled fractions against PBS, pH 7 4, and concentrate using an ultrafiltration membrane if required (see Section 3 1.1)... 

Figure 13.2 Schematic drawing of laboratory dialyzer developed by Craig [4] to separate low-molecular-weight impurities from biological solutions. This was the best method of performing this separation until ultrafiltration membranes became available in the late 1960s. The feed solution was circulated through the inside of the membrane tube solvent solution was circulated on the outside. Boundary layer formation was overcome by rotating the outer shell with a small motor...

While both of these devices use hollow fiber membranes similar to the primary components of kidney dialyzer units, the difference between the two techniques lies in how the analyte undergoes mass transport into the device. Microdialysis sampling is a diffusion-based separation process that requires the analyte to freely diffuse from the tissue space into the membrane inner lumen in order to be collected by the perfusion fluid that passes through the inner lumen of the fiber. Ultrafiltration pulls sample fluid into the fiber lumen by applying a vacuum to the membrane (Figure 6.1). 

Many classification schemes for hemodialysis membranes exist. Water permeability through the porous membranes is frequently used.14 Water permeability for a dialyzer is defined by the ultrafiltration coefficient for the particular device (KUF, mL/ h/mmHg). The KUF of any individual fiber will be related to the pore size and has an... 

When tetrahydrocannabinol in isotonic phosphate buffer was dialyzed against isotonic phosphate buffer, 50 - 100% of the drug was bound to the tubing used as the membrane. All of the drug was bound below 0.05 Ug/ml. Ultrafiltration was equally unsuccessful, since only 0 - 5% of the drug in isotonic phosphate buffer was recovered in the ultrafiltrate. 

Plastic microdevices for high-throughput screening with MS detection were also prepared for detection of aflatoxins and barbiturates. These devices incorporated concentration techniques interfaced with electrospray ionization MS (ESI-MS) through capillaries [2], The microfluidic device for aflatoxin detection employed an affinity dialysis technique, in which a poly (vinylidene fluoride) (PVDF) membrane was incorporated in the microchip between two channels. Small molecules were dialyzed from the aflatoxin/antibody complexes, which were then analyzed by MS. A similar device was used for concentrating barbiturate/antibody complexes using an affinity ultrafiltration technique. A barbiturate solution was mixed with antibodies and then flowed into the device, where uncomplexed barbiturates were removed by filtration. The antibody complex was then dissociated and electrokinetically mobilized for MS analysis. In each case, the affinity preconcentration improved the sensitivity by at least one to two orders of magnitude over previously reported detection limits. 

The CCC fractions, HDL-LDL and VLDL-serum proteins, were each separately dialyzed against distilled water until the concentration of the potassium phosphate was decreased to that in the starting buffer used for the hydroxyapatite chromatography. These two fractions were concentrated separately by ultrafiltration. The concentrates of both fractions were chromatographed on the hydroxyapatite column. Fig. 4 shows the elution profile on hydroxyapatite obtained from the HDL-LDL fraction. A 1.4-mL volume of the concentrate was loaded onto a Bio-Gel HTP DNA-grade column (5.0 x 2.5 cm I.D.)... 

A column of CM-Sephadex (2.5x20 cm, Pharmacia Biotech, Uppsala, Sweden) is prepared according to the manufacturer s instruction by using 10 mM PB, pH 6.0, as an equilibration buffer. Apply the dialyzed fraction to the column, wash with 200 ml of 10 mM PB, pH 6.0 (this percolate contains component I), and elute component II with a gradient from 0 to 0.4 M sodium chloride in 1000 ml of 10 mM PB, pH 6.0. Collect the fractions containing component II and concentrate by ultrafiltration through a P0200 membrane (UHP-43K, Advantec Co., Tokyo, Japan). 

Pressure Control of the Ultrafiltration Rate During Hemodialysis with High-Flux Dialyzers and the Time Dependence of Membrane Transport Parameters... 

In the counter-current mode the magnitude of this difference is set by the construction of the dialyzer and the dialysate pressure control and is generally on the order of 50 mm Hg or greater. This minimum pressure will induce an absolute minimum ultrafiltration rate of 350 ml/hr for a typical high flux membrane. Thus, when the patient has lost sufficient water or perhaps when he does not need to lose any water during dialysis, the patient must continuously be given sterile saline to make up for the minimum ultrafiltration loses. 

Ultrafiltration Results - Gambro High Flux Dialyzer... 

In Vivo Data for 1.36 m Gambro High Flux Dialyzer at Zero Ultrafiltration Rate and Blood Flow at 225 ml/mln... 

The results of this investigation which are clinically significant are 1) an accurate and simple means for controlling ultrafiltration during hemodialysis with "high flux" dialyzers has been developed, and 2) a formula which can accurately predict the ultrafiltration rate from measurement of hydrostatic pressures alone has been determined. It is now possible for any hemodialysis clinic to benefit from the use of high flux dialyzers by implementing the pressure control of ultrafiltration as described here. 

For some RNases, especially recombinant RNases, there can be a large loss of protein after concentration with a Centricon microconcentrator. Other methods of concentration, such as Diaflo ultrafiltration (Amicon Inc.) using a YM3 membrane, have not been successful in these cases. This concentration step can be avoided by either dialyzing as described in Note 1 or by starting with more material, such as 1 mL of a 10-20 mg/mL RNase solution. The final protein concentration should be 6.4 mg/mL. 

Preparation of Enzyme. Separation and purification of the enzyme from the liver of the common squid were as follows Squid livers were mashed and dispersed in five volumes of distilled water, then acidified to pH 4.0. Much oil was eliminated. This was followed by ultrafiltration, salting out with ammonium sulfate (50% saturation), dialyzing and freeze-drying in vacuo, to yield a crude enzyme. A purified enzyme was obtained from this crude enzyme by using column chromatography. Active fractions were separated by cation exchange resin. Mono S (Pharmacia) and further purified by gel-flltration column of Superdex 75 (Pharmacia). The active fractions were collected as the purified enzyme. 

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