Hormones, fractionation

Free Hormone Fraction by Indirect Equilibrium Tracer Dialysis... 

Several isotopic methods have been used to accurately estimate the free hormone fraction, including equilibrium tracer dialysis, ultrafiltration, Sephadex chromatography, and polyacrylamide gel filtration. However, these techniques are very cumbersome and time consuming for routine clinical use and, with the exception of equilibrium tracer dialysis, have found little practical application. Unfortunately the free hormone fraction as estimated in normal sera by equilibrium tracer dialysis varies substantially among laboratories. Methodological difficulties include the presence of residual impurities in the tracer, the temperature and duration of dialysis, tlie adsorption of tracer by components of the dialysis system, and the in vitro generation of free fatty acids. ... 

Principle. The free hormone fraction, as measured by dialysis or ultrafiltration of diluted serum containing tracer... 

Free Hormone Fraction by Uptake Methods Thyroid Hormone-Binding Ratio)... 

The THBR is derived from a version of the T3 or T4 uptake test. Uptake tests are used to estimate the number of unoccupied (unsaturated) thyroid hormone bindhig sites on serum proteins. This information is important because variations in total thyroid hormone concentrations in blood, as discussed previously, have resulted from changes in binding protein concentrations. Values obtained by uptake methods are expressed as a THBR, which is directly proportional to the free hormone fraction (within limits). Measurement of THBR, in conjunction with a total hormone concentration, is a clinically useful indirect method for calculating the FT4 (or FT3) index. The index approach is particularly useful in patients with nonthyroidal illness in whom FT4 immunoassay methodologies are unreliable. Specifically, TT4 measurement is more diagnostically useful in such patients provided that values are interpreted in accord with the severity of illness in the patient that is indirectly reflected by abnormalities in THBR. 

T3 uptake values are customarily expressed as matrix-bound counts divided by the total counts added (typical euthyroid reference iateiwal 25% to 37%). This calculation, however, is theoretically unsound and has led to problems of interpretation, particularly when serum TBG concentrations are very high or very low. Instead the uptake value should be expressed tis the matrix-bound counts divided by the counts that remain bound to serum proteins (typical euthyroid reference interval 33% to 50%). This result corresponds more closely to the mass action law and is more linearly related to the free hormone fraction over a wide range of values. 

S. Sensitivity of the Radioimmunoassay. This depends on two factors. First, the hormone must be labeled with suflScient radioactive nuclide to allow the counting of free and antibody bound hormone fractions to be statistically significant at the end of the incubation period. Second, provided that the protein can be labeled to a high enough specific activity, the sensitivity of the test will depend on the equilibrium constant of the antibody-antigen system in use. The higher the constant in favor of the complex formation, the more sensitive will be the assay. 

Different substances, such as lipids, lipoproteins, hormones, fractions of plasma, toxins, etc., are included in the last part of Table 4.7.5. From the point of view of practical application of bioaffinity chromatography an important example is industrial blood plasma fractionation [220]. 

Clarke, W. Schiel, J.E. Moser, A. Hage, D.S. Analysis of free hormone fractions by an ultrafast immunoextrac-tion/displacement immunoassay Studies using free thyroxine as a model system. Anal. Chem. 2005, 77, 1859-1866. 

From 1,53 g of starting material, 106 mg of adrenocorticotropic hormone, fraction 8 B, was obtained. This material was almost homogeneous on electrophoresis. The yield of almost 7 per cent was half that obtained with adrenocorticotropic hormone from pigs. On the other hand, several fractions, viz., 4 A, 5 B, 6 B and 7 A, also had relatively high corticotropin activity. The amino acid analyses of these samples were almost identical. The combined weight of Fractions 4 A, 5 B,... 

Sepharose (e.g. Sepharose CL and Bio-Gel A) is a bead form of agarose gel which is useful for the fractionation of high molecular weight substances, for molecular weight determinations of large molecules (molecular weight > 5000), and for the immobilisation of enzymes, antibodies, hormones and receptors usually for affinity chromatography applications. 

Abscisin II is a plant hormone which accelerates (in interaction with other factors) the abscission of young fruit of cotton. It can accelerate leaf senescence and abscission, inhibit flowering, and induce dormancy. It has no activity as an auxin or a gibberellin but counteracts the action of these hormones. Abscisin II was isolated from the acid fraction of an acetone extract by chromatographic procedures guided by an abscission bioassay. Its structure was determined from elemental analysis, mass spectrum, and infrared, ultraviolet, and nuclear magnetic resonance spectra. Comparisons of these with relevant spectra of isophorone and sorbic acid derivatives confirmed that abscisin II is 3-methyl-5-(1-hydroxy-4-oxo-2, 6, 6-trimethyl-2-cyclohexen-l-yl)-c s, trans-2, 4-pen-tadienoic acid. This carbon skeleton is shown to be unique among the known sesquiterpenes. 

Porath, J, Some Recently Developed Fractionation Procedures and Their Application to Peptide and Protein Hormones, Pure and Applied Chemistry 6, 233, 1963. 

Male infertility may result from cancer surgery, radiotherapy, hormonal imbalances, or damage of germinal stem cells. Testicular damage from radiotherapy depends on the treatment field, total dose, and fractionation schedule. Depending on the radiation, sperm counts may return to pretreatment levels in 10 to 24 months after therapy or maybe permanent in 80% of men after total-body irradiation for transplant. 

After exerting their action in the organism, natural and synthetic hormones are catabolized in the liver by conjugation to glucuronide and/or sulfate moieties, forming more polar conjugated forms which are excreted via urine. This is the main route of hormone excretion in humans and pigs. A fraction of hormones is also excreted in a free form via feces in animals such as sheep and cattle this is the main route for hormone excretion (Table 3) [66, 67],... 

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