Osmole

Fc function (portion of fully functional immunoglobulin molecule) prekailikrein activator, <35 lU/mL HBsAs antibody, >1 lU/g normal subclass distribution osmolality, <280 mosmol 4 to 7.4 pH. Ref. 221. 

R. Walter and co-workers. Disturbances in Body Fluid Osmolality, American Physiological Society, Betbesda, Md., 1977, pp. 1—36. 

High Osmolality Contrast Media. An important advance in radiopaques came with the synthesis of aminotriiodoben2oic acid and its acetylated derivative, acetrizoic acid [85-36-9] (5) (8,9). Aqueous solutions of sodium acetrizoate possessed the thermal stabiUty so that they could be autoclaved (10) with minimal decomposition. The higher iodine content, ie, 3 atoms/molecule, increased the contrast efficiency, and the clinical safety of acetrizoate was improved over that of the earlier urographic agents. 

Low Osmolality Contrast Media. An ideal intravascular CM possesses several properties high opacity to x-rays, high water solubihty, chemical stabihty, low viscosity, low osmolahty, and high biological safety. Low cost and patentabihty are also important for commercial agents. The newer nonionic and low osmolar agents represent an advanced class of compounds in the development of x-ray contrast media. 

Table 3. Properties of Low Osmolality Contrast Media (LOCM) for Angiography and Urography ...

Fig. 2. Schematic representation of relevant electrolyte transport through the renal tubule, depicting the osmolar gradient ia medullary iaterstitial fluid ia ywOj yW where represents active transport, —passive transport, hoth active and passive transport, and passive transport of H2O ia the presence of ADH, ia A, the cortex, and B, the medulla. An osmole equals a mole of solute divided by the number of ions formed per molecule of the solute. Thus one mole of sodium chloride is equivalent to two osmoles, ie, lAfNaCl = 2 Osm NaCl. ADH = antidiuretic hormone.

MNaci 2nd M iaci 3re osmolal concentrations of electrolyte in the presence and absence of additive and R is osmolal ratio of cryoprotectant to electrolyte. 

Previous studies indicate that osmotic gradients promote membrane fusion, while hyperosmotic conditions inhibit membrane fusion during exocytosis. Consistent with this idea is the observation that the release of lysosomal enzymes from rabbit neutrophils, induced by the chemotactic peptide J -formylmethionyl-leucyl-phenylalanine (FMLP), is inhibited almost 80% in a 700-mosmol/kg medium. Inhibition is immediate (within 10 s), increases with osmolality, and is independent of the osmoticant. Neutrophils loaded with the calcium indicator indo-1 exhibit an FMLP-induced calcium signal that is inhibited by hyperosmolality. Hyperosmolality (700 mosmol/kg) increases basal calcium levels and reduces the peak of the calcium signal elicited by FMLP at concentrations ranging from 10 ° to 10 M. 

Figure 7. Sensitivity of the FMLP-induced calcium signal to removal of extracellular calcium. Indo-l-loaded neutrophils were stimulated with 10 M FMLP in a medium of normal osmolality (320 mosmol/kg) and indo-1 fluorescence was recorded as described in Figure 6. Trace 1 Cells in a medium with normal calcium (1.5 mN). Trace 2 EGTA added to chelate extracellular calcium before stimulation extracellular calcium (1.5 milf) readded 70 s after stimulation. Trace 3 Cells in a medium with normal calcium EGTA added 70 s after stimulation to chelate extracellular calcium.

Confirmation that FMLP-induced activation involves release of intracellular calcium was obtained by loading neutrophils with CTC. Addition of 20 pH CTC to a neutrophil suspension resulted in a gradual increase in CTC fluorescence as the probe entered the cells and partitioned into intracellular membranes (Figure 9, upper panel). Addition of FMLP resulted in an abrupt decrease in fluorescence, suggesting release of calcium from intracellular membranes probed by CTC. The FMLP-induced release of calcium monitored by CTC was little affected by increased medium osmolality a similar fluorescence decrease was seen in the presence of sodium HEPES (645 mosmol/kg) or sodium sulfate (662 mosmol/kg) (Figure 9, lower panel). 

CTC, and CTC fluorescence (excitation 400 nm, emission 430 nm) was monitored versus time at 37°C. Addition of 10 H FMLP at the arrow resulted in an abrupt decrease in CTC fluorescence. Lower panel Increasing medium osmolality by addition of either sodium sulfate (middle trace) or sodium HEPES (right trace) had little effect on the FMLP induced decrease in CTC fluorescence when compared to that seen in medium of normal osmolality (left trace). ... 

A series of calibration standards (CS) is made up that covers the concentration range from just above the limit of detection to beyond the highest concentration that must be expected (extrapolation is not accepted). The standards are made up to resemble the real samples as closely as possible (solvent, key components that modify viscosity, osmolality, etc.). A series of blinded standards is made up (usually low, medium, high the analyst and whoever evaluates the raw data should not know the concentration). Aliquots are frozen in sufficient numbers so that whenever the method is again used (later in time, on a different instrument or by another operator, in another laboratory, etc.), there is a measure of control over whether the method works as intended or not. These so-called QC-standards (QCS) must contain appropriate concentrations of all components that are to be quantified (main component, e.g., drug, and any impurities or metabolites). 

The mechanisms of the allergy-like reactions to RCM are still a matter of speculation (table 2). Anaphylaxis to RCM has been discussed to be due to a direct membrane effect possibly related to the osmolality of the RCM solution or the chemical structure of the RCM molecule (pseudo-allergy) [2], an activation of the complement system [27], a direct bradykinin formation [28], or an IgE-mediated mechanism [3]. 

Garcia-Morales EJ, Cariappa R, Parvin CA. Osmole gap in neurosurgical-neurosurgical intensive care unit its normal value, calculation, and relationship with mannitol serum concentrations. Crit Care Med 2004 32(4) 986-991. 

Use nonionic and either low or iso-osmolal products ° Example, iodixanol... 

Excess effective osmoles in the extracellular fluid ° Hyperglycemic state or use of mannitol... 

Urine osmolality <100 mOsm/kg (anti-diuretic hormone [ADH] suppressed)... 

Beer potomania syndrome or tea and toast diet ° Urine osmolality >100 mOsm/kg (ADH present)... 

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