Biological dialysis

Until the early 1960s, laboratory iavestigators rehed on dialysis for the separation, concentration, and purification of a wide variety of biologic fluids. Examples iaclude removal of a buffer from a proteia solution or concentrating a polypeptide with hyperosmotic dialysate. Speciali2ed fixtures were sometimes employed alternatively, dialysis tubes, ie, cylinders of membrane about the si2e of a test tube and sealed at both ends, were simply suspended ia a dialysate bath. In recent years, dialysis as a laboratory operation has been replaced largely by ultrafiltration and diafiltration. 

Aluminium is the most abundant element of the lithosphere. Although a large number of persons are exposed world-wide to Al, the incidence of pulmonary effects is low (Schaller et al. 1994). In the 1970 s the effect of Al appearing in dialysis solutions on the central nervous system has become weU known. Increased Al could also be detected in several brain regions of patients with Alzheimer s disease. For the determination in biological materials the most widely used method is GF-AAS. 

The ability of S -nitrosothiols to mimic many of the biological properties of NO itself may emanate from in vivo decomposition to generate NO. This decomposition is catalysed by Cu2+,n and may be important in the development of thrombo-resistant devices used in kidney dialysis or coronary by-pass surgery.196 It is also possible that direct transfer of NO from RSNO occurs in biological systems.197... 

The suitable materials for the above mentioned domains are polymers, metals and ceramics. Among these, polymers play an important role. Even the polymers have a lot of remarkable properties that could be used in biomaterials design, the interaction between these artificial materials and tissues and blood could create serious medical problems such as clot formation, activating of platelets, and occlusion of tubes for dialysis or vascular grafts. In the last few years, novel techniques of synthesis have been used to correlate desirable chemical, physical and biological properties of biomaterials. 

A separation step is sometimes an essential part of an analytical method and may be as diverse as distillation, filtration, digestion, extraction, phase-separation or dialysis. These can all be performed by continuous flow analysers either by adding a specially designed glass fitting to the manifold or analytical cartridge or by the addition of a separate module to the analyser. Many biological samples contain protein and dialysis is often used to remove this protein, which would otherwise affect the analysis. 

Vinyl alcohol copolymer gel is hydrophilic and has been developed for aqueous-phase size-exclusion liquid chromatography however, it is less polar than the polysaccharides. Its specificity permits the direct injection of a biological sample without deproteinization. For example, blood serum from a patient suffering from chronic nephritis has been injected directly as a measure of the degree of dialysis (Figure 3.17). Adenosine triphosphate, adenosine diphosphate, and adenosine monophosphate in red blood cells have also been separated directly (Figure 3.18). Theophylline in blood serum has been... 

If the soluble protein that specifically adsorbs to the fiber can be extrinsi-cally labeled, the background problem can be avoided. Of course, in vivo proteins cannot be labeled. However, it is conceivable that a protein labeled with a bulky extrinsic group (e.g., fluorescent dextrans) could be confined by a molecular sieve membrane (e.g., a dialysis membrane) within a closed volume surrounding the specifically derivatized optical fiber. When exposed to the (unlabeled) protein in the biological fluid under investigation, the membrane-clad fiber would allow some unlabeled protein to permeate in and... 

Diagram of the Womack-Colowick flow dialysis apparatus Reprinted with permission of the Journal of Biological Chennistry. 

Dialysis, which involves mass transfer between two miscible liquids separated by a membrane, has been widely used in continuous systems [1], particularly in clinical analysis as a means for separating macromolecules present in biological fluids from the species of interest (of generally low molecular weights). 

Diazinon is rapidly metabolized, with an estimated mammalian biological half-life of 12-15 hours (Iverson et al. 1975 Mucke et al. 1970). Consequently, efforts at reducing body burdens of poisoned persons may not be critical to the outcome. Dialysis and hemoperfusion are not indicated in organophosphate poisonings because of the extensive tissue distribution of the absorbed doses (Mucke et al. 1970 Poklis et al. 1980). 

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