Radioactive chromium

Chromium coatings are applied on the surface of other metals for decorative purposes, to enhance resistance, and to lower the coefficient of friction. Radioactive chromium-51 is used as a tracer in the diagnosis of blood volume. 

An example of the many in vivo procedures using radioactive agents is the determination of whole-blood volume by injecting a known quantity of red blood cells labeled with radioactive chromium-51. After a suitable interval to allow the labeled cells to be distributed evenly throughout the body, a blood sample is taken, the amount of dilution of the 51Cr is measured, and the blood volume is calculated. Recall from Section 3.8 that when a concentrated solution is diluted, the amount of solute (51Cr in the present instance) remains the same and only the volume changes. That is,... 

A person s blood volume can be found by injecting a small amount of radioactive chromium-51 and measuring the dilution factor. 

An alternative method which can also be automated by the use of the Titertek supernatant harvester (see Appendix 3) involves the measurement of radioactive chromium released into the culture medium from killed cells. The harvester consists of a set of absorbent cylinders aligned so that they may be inserted into the wells of a microtitration plate (Appendix 3). Once the supernatant in the wells has been absorbed the cylinders are transferred to counting vials and the amount of radioactive chromium released from the cell monolayer is estimated. Cells take up 51 Cr sodium chromate rapidly and the excess is readily washed away by rinsing in culture medium. 

An acute, oral dose of radioactive chromium(III) as chromium chloride or chromium(VI) as sodium chromate was administered to humans after which feces and urine were collected for 24 hours and 6 days, respectively, and analyzed for chromium. The amount of chromium in the 6-day fecal collection was 99.6 and 89.4% of the dose for chromium(ni) and chromium(VI) compounds, respectively. The amount of chromium in the 24-hour urine collection was 0.5 and 2.1% of the dose for chromium(ni) and chromium(VI) compounds, respectively (Donaldson and Barreras 1966). In subjects drinking 0.001-0.1 mg chromium(VI)/kg/day as potassium chromate in water for 3 days, <2-8% of the dose was excreted in the urine (Finley et al. 1997). The percentage of the dose excreted appeared to increase with increasing dose. 

A method for predicting the safety of transfusion is based on the use of cells labeled with radioactive chromium (74). After the administration of several milliliters of the labeled blood, the survival of erythrocytes in the recipient s circulation is examined poor survival in vivo indicates that transfusion with these erythrocytes will be hazardous (75,76). There are two types of survival curve for incompatible erythrocytes. A curve described by a single exponential function is seen with most potent IgG antibodies that do not bind complement, including anti-D, anti-C, and anti-K, antibodies. Clearance described by more than one exponential is observed with complement-binding antibodies (77). In the latter there is a slowing of erythrocyte destruction 5-20 minutes after injection... 

Certain salts of radioactive chromium (1) are used as radiopharmaceutical tracers in various hematological procedures. Chromium compounds are also used in oral and parenteral nutrition and in artificial hip and knee joints. Chromium picolinate has been promoted as a nutritional supplement and has received a great deal of interest because of its possible beneficial effects on muscle strength and body composition. 

The radioactive chromium (51Cr) found in Columbia River sediments contaminated with effluent from a nuclear reactor facility was not released by the major cations of sea water or by 0.05 M CuS0424 . The results of previous work in this laboratory (New England Aquarium) showed that of the silver(I) and cadmium(II) adsorbed on the clay minerals kaolin and montmorillonite, in essentially deionized water, less than half was desorbed on mixing with sea water25 . One may postulate from results such as these that most of the heavy metals occluded within a complex organic... 

Prepd from radioactive chromium ( ICr) which has a half-life of 26.5 days. The emission of gamma rays is applicable to biological tagging and tracing. Other properties identical with those of Ordinary sodium chromate. Available as soln for intravenous injection or for mixing with blood. Unbound chromate in the plasma can be reduced with ascorbic add or may be removed by separation aud washing of cells. 

The role of chemisorption in the mechanism of passivity is borne out by the typical patterns of data, having the same shape as adsorption isotherms, which describe concentration of radioactive chromium on the surface of iron passivated by chromates (11), or by potential changes induced by surface concentration of chromates (12), both as a function of chromate concentration in solution (Figure 1). It is also illustrated by the initially rapid rate, followed by a measurably slow rate, with which metals achieve passivity as followed by potential change with time for iron immersed in chromates or by 18-8 immersed in aerated water (IS) (Figure 2), and by... 

Gray SJ, Sterling K (1950) The tagging of red cells and plasma proteins with radioactive chromium. J Clin Invest 29 1604-1613 Gumbleton M, Nicholls PJ (1988) Dose-response and time-response biochemical and histological study of potassium dichromate-induced nephrotoxicity in the rat. Food Chem Toxicol 26 37-44... 

The classical assay that has been used for years to monitor cytotoxicity is the Cr release assay. Briefly, the target cells in either ADCC or CDC assay are labeled with radioactive chromium. In an ADCC assay the target cells with... 

Arvidsson, B., Magnusson, B., Solvell, L. and Magnusson,A. (1975) Acetylsalicylic acid and gastrointestinal bleeding. Measurement of blood loss using a modified radioactive chromium method. Scand. J. Gastroent., 10, 155. 

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