Plasma filtration

The kidney regulates the acid-base balance of the body by control over resorption of sodium ions, which may exchange for hydrogen ions in the kidney tubule. Since most dietaries are of acid-ash, the urine is usually more acid than the original plasma filtrate and much of the phosphate excreted is thus changed to the acid monosodium salt, Within the range of normal variability, with an alkaline ash diet, the urine may become alkaline, and in extreme instances, some sodium bicarbonate may be excreted. 

Raida, M., Schuiz-Knappe, P., Heine, G., Forssmann, W. G. (1999). Liquid chromatography and electrospray mass spectrometric mapping of peptides from human plasma filtrate. J. Am. Soc. Mass Spectrom. 10, 45-54. 

Instead of using a furrowed or dimpled membrane support plate, Sobey [41] observed that a single flow deflector in a flat membrane channel could produce many vortices under oscillatory flow conditions, an effect named the vortex wave. An important feature of the vortex wave is that it could occur under low crossflow velocity conditions or with laminar flow so that it can be used for shear-sensitive fluids. Millward et al. [42] tested the effect of vortex waves on plasma filtration with waves produced by flow deflectors with cross-sectional area of 1 x 1 mm in a 2.25 mm high channel as shown in Figure 8.22. The aim was to improve membrane applications for the separation of plasma from cellular blood components for both donor... 

Many researchers have assessed the effect of pulsatile flow on different membrane processes with wide range of feeds. One of the first studies was by Kennedy et al. [48] who showed that flux in the RO of sucrose solution could increase by 70% by pulsatile flow at 1 Hz. Gupta et al. [49] reported a 45% enhancement of flux in MF of raw apple juice with a pressure waveform provided by a fast piston return followed by a fast forward stroke at 1 Hz. Jaffrin [50], using hollow fiber filters, demonstrated a 45% enhancement in flux in plasma filtration. Using the collapsible-tube oscillation generator described above, Bertram et al. [47] demonstrated that pulsation resulted in a 60% increase in permeate flux in the filtration of silica suspensions. 

Millward HR, Bellhouse BJ, Sobey U, and Lewis RWH, Enhancement of plasma filtration using the concept of the vortex wave, J. Membr. Sci. 1995 100 121-129. 

The rapid onset of edema dilutes the acids that arrive in the immediate surroundings of the blood vessels and prevents protein coagulation in the vessel walls blood continues to circulate. When there is too much acid, extravascular plasma filtration can no longer make up for the fall in pH, and the vessel walls coagulate. Blood no longer circulates, and the skin changes color from pink-white to pure white or even gray. 

Sample preparation Filter (0.45 jim) urine or plasma. Mix plasma filtrate with an equal volume of 50 mM pH 8.0 Tris-sulfuric acid buffer containing 0.1 mM zinc acetate and 40 mM sodium dodecyl sulfate. Inject a 50 p,L aliquot of the urine filtrate or the diluted plasma onto column A with mobile phase A, elute to waste with mobile phase A, after 5 min backflush the contents of column A onto column B with mobile phase B, after 3 min remove column A from the circuit, elute column B with mobile phase B, monitor the effluent from column B. Re-equilibrate column A with mobile phase A for 5 min before next injection. 

Figure 15.3 (a) Principle of construction of (A) artificial kidney and (B) artificial bladder (1) flow of blood, (2) flow of ultrafiltrate, (3) plasma-filtrating membrane, (4) adsorbing material, (5) ultrafiltration membrane, (b) Reasonable disposition of the artificial kidney (A) artificial kidney, (B) artificial bladder, (C) artificial ureter, (D) Implanted arteries and venous canulas. (Reprinted from [356] with permission of Elsevier.)... 

Acid tubular Alkaline tubular Tubule Plasma filtrate, filtrate wall... 

FIGURE 10.24 Plasma flux obtained with flow deflector-equipped channel with and without pulsation. (Reprinted from J. Membr. Sci., 100, Millward, H.R., Bellhouse, B.J., Sobey, I.J., and Lewis, R.W.H., Enhancement of plasma filtration using the concept of the vortex wave, 121-129, Copyright 1995, with permission from Elsevier.)... 

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