Solution hyperosmotic

The starting material for the affinity purification was predominantly plasma membrane from presumably well-coupled cells therefore, the con-nexin that is isolated is most likely from junctional structures. Because the purified connexin-32 is predominantly in structures the size of single hemichannels, a simple conclusion is that octylglucoside can disrupt the end-to-end interactions of junctional channels. However, there is the caveat that the junctions may split prior to solubilization, that is, in the preparation of the crude plasma membrane fraction. Junctions can split when a tissue is perfused with hyperosmotic solutions (II7), so a cellular splitting could precede disruption of junctional channels by octylglucoside. 

There are several possible improvements in the treatment of patients with sphingolipidoses. Firstly the blood-brain barrier can be altered under certain conditions. For example, a-mannosidase can enter the brain if the barrier is altered by injecting hyperosmotic solutions of mannitol into the external... 

Mouthwashes need not be made iso-osmotic. But strongly hyperosmotic solutions may hurt in case of lesions in the mouth. Sorbitol solution, because of its viscosity sometimes used as vehicle for suspensions, is strongly hyperosmotic. For patients with lesions a formulation sometimes has to be adapted. For instance many chlorhexidine mouthwashes contain sorbitol as a flavouring and ethanol as preservative. In the following adapted version both are omitted (Table 7.3). 

For rectal administration, the osmotic value may vary within wide limits. An osmotic value corresponding to a 0-1.8 % sodium chloride solution is tolerated. Adjusting the iso-osmotic value of an enema, by addition of, for example, sodium chloride, offers no advantage regarding activity and irritation, and can be omitted. StrrMig hyperosmotic solutions must be avoided in enemas, except for those intended as laxative. A strrMigly hyperosmotic solution, for example a phosphate enema, induces a defecation reflex. The osmotic value of this enema is about seven times higher than that of a normal saline solution. 

As a measure of the tonicity of blood one can calculate with the osmotic value because active substances and additives cannot pass the membrane of the erythrocyte (see Sect. 18.5.2). The osmotic value of blood is around 290 mOsm/kg. Some parenteral fluids however contain substances that can pass the membrane fast ethanol, glycerol, urea. Hyperosmotic solutions of these substances may cause haemolysis so they are hypotonic. The iso-osmotic concentration of ethanol is for example 1.39 % m/m. Ethanol 5 % v/v infusion fluid is therefore hyperosmotic but appears to be practically isotonic. 

With peritoneal dialysis the peritoneum, which is well supplied with blood vessels, functions as a semipermeable membrane. Peritoneal dialysis solutions are sterile hyperosmotic solutions. These solutions withdraw water from the blood through the peritoneum. The transport of small ions takes place at the same time. 

The abdomen is surrounded by the peritoneum, an endothelial, single cellular layer that functions as dialysis membrane for water and small molecules. By using a hyperosmotic solution for peritoneal dialysis water and small molecules are withdrawn from the blood. After several hours the fluid is rinsed out and replaced with new CAPD solution. Solutions for peritoneal dialysis are made iso to hyper-osmotic with glucose to remove water from the body. 

Irrigations to rinse a surgical area or a deep wound should be iso-osmotic. For disinfection or cleansing of superficial wounds this is not strictly necessary. Historically, a sterile hyperosmotic solution (NaCl 3 %, for example) is prepared for rinsing superficial moist wounds and bedsores. Hypertonicity is in fact the mechanism of action the solution has a desiccating effect. For irrigations for the bladder iso-osmosis is less important. Hypo-osmosis is more problematic than hyper-osmosis, because the osmotic value of urine is twice to trice the osmotic value of blood [4]. 

Fat emulsions for intravenous nutritional purposes have been developed to furnish abundant calories in a small volume without risks inherent in hyperosmotic solutions. They are also a good source of poly-unsaturated acids. A number of different kinds of observations show that such fat is well utilized by a variety of animal species and by humans. Intralipid which is based on soybean oil and egg lecithin has been widely used with few adverse reactions. Even in humans very high doses have not produced ill effects. Of all emulsions tested in monkeys only 107o Intralipid was well tolerated. Simultaneous infusion of solutions of... 

Fenstermacher, J., Gazendam, J., 1981. Intra-arterial infusions of drugs and hyperosmotic solutions as ways of enhancing CNS chemotherapy. Cancer Treat. Rep. 65 (Suppl. 2), 27-37. 

The permeability of small molecules other than water can be determined by simply transferring vesicles into a hyperosmotic solution containing the test solute. Preliminary studies transferred a vesicle (200 mOsm sucrose inside) from a glucose solution (200 mOsm) into a urea solution (240 mOsm). As shown in Figure 9.16, the vesicle volume first reduced then increased. 

Compounds suitable for encapsulation within the aqueous core of liposomes should be soluble in water at relatively high concentrations, hydrolytically stable, and have a large boron content with a low osmotic stress. The high concentrations of boron required to achieve therapeutic levels in vivo necessitates the encapsulation of hyperosmotic solutions of the polyhedral borane salts with up to three times the osmotic pressure of the external solution. 

Doctors and others healthcare workers often administer solutions to patients. The osmotic pressure of these solutions is controlled for the desired effect on the patient. Solutions having osmotic pressures greater than those of body fluids are called hyperosmotic. These solutions take water out of cells and tissues. When a human cell is placed in a hyperosmotic solution, it tends to shrivel as it loses water to the surrounding solution (Figure 12.18b ). Solutions having osmotic pressures less than those of body fluids are called hyposmotic. These solutions pump water into cells. When a human cell is placed in a hyposmotic solution—such as pure water, for example—water enters the cell, sometimes causing it to burst (Figure 12.18c). 

Isosmotic solution Hyperosmotic solution Hyposmotic solution... 

FIGURE 12.18 Red Blood Cells and Osmosis (a) In an isosmotic solution, red blood cells have the normal shape shown here. In a hyperosmotic solution (b), they lose water and shrivel. In a hyposmotic solution (c), they swell up and may burst as water flows into the cell. 

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