Blood plasma processing

Blood Plasma Processing. Purified therapeutic proteins are derived from human blood plasma via cryoprecipitation followed by sequential precipitations effected through increasing ethanol concentrations at controlled temperature, pH and ion composition ("Cohn precipitation"). As discussed in the section on fractionation of solutes, UF cannot be used to fractionate the various plasma... 

Human blood plasma contains over 700 different proteins (qv) (1). Some of these are used in the treatment of illness and injury and form a set of pharmaceutical products that have become essential to modem medicine (Table 1). Preparation of these products is commonly referred to as blood plasma fractionation, an activity often regarded as a branch of medical technology, but which is actually a process industry engaged in the manufacture of speciaUst biopharmaceutical products derived from a natural biological feedstock (see Pharmaceuticals). 

Protein-Based Substitutes. Several plant and animal-based proteins have been used in processed meat products to increase yields, reduce reformulation costs, enhance specific functional properties, and decrease fat content. Examples of these protein additives are wheat flour, wheat gluten, soy flour, soy protein concentrate, soy protein isolate, textured soy protein, cottonseed flour, oat flour, com germ meal, nonfat dry milk, caseinates, whey proteins, surimi, blood plasma, and egg proteins. Most of these protein ingredients can be included in cooked sausages with a maximum level allowed up to 3.5% of the formulation, except soy protein isolate and caseinates are restricted to 2% (44). 

Plasma processing technologies ate used for surface treatments and coatings for plastics, elastomers, glasses, metals, ceramics, etc. Such treatments provide better wear characteristics, thermal stability, color, controlled electrical properties, lubricity, abrasion resistance, barrier properties, adhesion promotion, wettability, blood compatibility, and controlled light transmissivity. 

The most important type of mixed solution is a buffer, a solution in which the pH resists change when small amounts of strong acids or bases are added. Buffers are used to calibrate pH meters, to culture bacteria, and to control the pH of solutions in which chemical reactions are taking place. They are also administered intravenously to hospital patients. Human blood plasma is buffered to pH = 7.4 the ocean is buffered to about pH = 8.4 by a complex buffering process that depends on the presence of hydrogen carbonates and silicates. A buffer consists of an aqueous solution of a weak acid and its conjugate base supplied as a salt, or a weak base and its conjugate acid supplied as a salt. Examples are a solution of acetic acid and sodium acetate and a solution of ammonia and ammonium chloride. 

Enzymes occupy an important place in analytical biochemistry and many investigations require their detection and quantitation. Studies of the enzyme content of blood plasma are particularly useful in clinical biochemistry both in the monitoring of normal metabolic processes and in the detection of abnormal levels of enzyme production or release. Enzyme assays also provide convenient methods for assessing the quality of foodstuffs and checking the efficiency of sterilization and pasteurization processes. 

Calcitriol and parathyroid hormone, on the one hand, and calcitonin on the other, ensure a more or less constant level of Ca "" in the blood plasma and in the extracellular space (80-110 mg 2.0-2.6 mM). The peptide parathyroid hormone (PTH 84 AA) and the steroid calcitriol (see p. 374) promote direct or indirect processes that raise the Ca "" level in blood. Calcitriol increases Ca "" resorption in the intestines and kidneys by inducing transporters. Parathyroid hormone supports these processes by stimulating calcitriol biosynthesis in the kidneys (see p. 330). In addition, it directly promotes resorption of Ca "" in the kidneys (see p. 328) and Ca "" release from bone (see B). The PTH antagonist calcitonin (32 AA) counteracts these processes. 

CSF Alls the intracerebral (intraventricular 20%) and extracerebral (subarachnoidal 80%) space. CSF originates from plasma (ultraflltration) as well as from choroid plexus (active secretion) in the ventricles, flows through cisternae and the subarachnoid space, and finally drains through the arachnoid villi into venous blood. Equilition processes establish a physiological ratio between composition and resorption of CSF. CSF flow starts around the time of birth and reaches its maximum rate at four months after birth, following the complete maturation of the arachnoid villi. 

At least three other families of plasma membrane proteins are also involved in surface adhesion (Fig. 11-22). Cadherins undergo homophilic ( with same kind ) interactions with identical cadherins in an adjacent cell. Immunoglobulin-like proteins can undergo either homophilic interactions with their identical counterparts on another cell or heterophilic interactions with an integrin on a neighboring cell. Selectins have extracellular domains that, in the presence of Ca2+, bind specific polysaccharides on the surface of an adjacent cell. Selectins are present primarily in the various types of blood cells and in the endothelial cells that line blood vessels (see Fig. 7-33). They are an essential part of the blood-clotting process. 

Tin metabolic acidosis (p. 652) there is an increase in glutamine processing by the kidneys. Not all the excess NH4 thus produced is released into the bloodstream or converted to urea some is excreted directly into the urine. In the kidney, the NH% forms salts with metabolic acids, facilitating their removal in the urine. Bicarbonate produced by the decarboxylation of a-lcetoglutarate in the citric acid cycle can also serve as a buffer in blood plasma. Taken together, these effects of glutamine metabolism in the kidney tend to counteract acidosis. ... 

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