Serum iron analysis

What is the purpose of neocuproine in the serum iron analysis ... 

The method of choice for serum iron analysis has been recommended by the International Committee for Standardization in Haematology (ICSH) [42]. This reference procedure obviates problems that are inherent in convenient automated methods that are precise but inaccurate [43]. In the recommended reference method, iron is released from transferrin with trichloroacetic acid (TCA), which precipitates apotransferrin and other serum proteins that are removed by centrifugation. Fe in the supernatant fluid is reduced to Fe " with thioglycolic (mercaptoacetic) acid, which is then complexed with a chromogenic iron-chelating reagent whose color is proportional to iron concentration. 

A 6-month-old infant has been fed unmodified cow s milk supplemented with com flour. He was healthy except that he was severely anemic, and an X-ray of his wrist showed retarded bone development. His hemoglobin was only 4.5 g/dL, and he had an elevated serum alkaline phosphatase. He was treated with iron supplements, folate, and ascorbic acid to no avail. Then serum copper analysis was done, and it showed a level of 9 fig/dL (normal is 85-163 /ig/dL). Thereupon his diet was supplemented with copper sulfate, and he showed dramatic improvement. Address the following questions ... 

Lalouel JM, Le Mignon L, Simon M, Fauchet R, Bourel M, Rao DC, et al. Genetic analysis of idiopathic hemochromatosis using both qualitative (disease status) and quantitative (serum iron) mformation. Am J Hum Genet 1985 37 700-18. 

B. F. Rocks, R. A. Sherwood, Z. J. Turner, and C. Riley, Serum Iron and Total Iron-Binding Capacity Determination by Flow Injection Analysis with Atomic Absorption Detection. Ann. Clin. Biochem., 20 (1983) 72. 

Hemoglobin in fresh sera does not interfere in the assay, but the acid reagent liberates iron from lyophilized hemoglobin. Hemolysis should therefore be avoided in collecting serum for iron analysis. 

Of particular interest will be the iron and calcium data. However, other nutrients must also be carefully considered. Unfortunately, data on the zinc content of food is as yet unavailable and will have to wait for later analysis. Regression analysis between serum ferritin levels and blood lead concentrations will be performed as well as a comparison with other hematological determinations such as free erythrocyte protoporphyrins, hemoglobin, hematocrit, and serum iron, which are all indicators of iron status. 

Mason, A.B., Halbrooks, P.J., James, N.G., Connolly, S.A., Larouche, J.R., Smith, V.C., MacGillivray, R.T.A. and Chasteen, N.D. (2005) Mutational analysis of C-lobe ligands of human serum Transferrin insights into the mechanism of iron release, Biochemistry, 44, 8013-8021. 

Iron for biosynthesis is transported through the bloodstream by the protein transferrin. The following procedure measures the Fe content of transferrin 10 This analysis requires only about 1 p,g for an accuracy of 2-5%. Human blood usually contains about 45 vol% cells and 55 vol% plasma (liquid). If blood is collected without an anticoagulant, the blood clots, and the liquid that remains is called serum. Serum normally contains about 1 pg of Fe/mL attached to transferrin. 

According to Beer s law, the intercept should be 0, not 0.0015. However, we will use the observed intercept for our analysis. Find the concentration of iron in the serum. 

The siderophore enterobactin (enterochelin) (64) is a cyclic lactone of three N-(2,3-dihydroxybenzoyl) L-serine moieties produced by E. coli under iron stress. Enterobactin (64) was first isolated from iron-limited cultures of Salmonella typhimur-ium [83], E. coli [84], and Aerobacter aerogenes [84]. Structural analysis has confirmed that 64 chelates iron as a hexadentate ligand via the two hydroxyl groups on each catechol moiety (see Fig. 13) [85]. Of all the siderophores characterized to date, 64 has been shown to have the highest affinity for ferric iron, with a stability constant of 1052 M 1 [86, 87], which is remarkable, considering the affinity of EDTA for iron is 27 orders of magnitude lower. In mammals, serum albumin [88] and siderocalin [89, 90] bind the hydrophobic 64 which impedes siderophore-mediated transfer of iron to bacteria. Consequently, bacteria such as E. coli and... 

The first crystallographic studies on transferrins date back more than 20 years (58), and crystals of various transferrins have since been reported. These include the diferric forms of rabbit (59) and human (60) serum transferrins, hen (61) and duck (62) ovotransferrins, human (63) and bovine (64) lactoferrins, and the apo- (iron free) forms of human lactoferrin (65) and duck ovotransferrin (62). In spite of all this activity, the crystals in many cases have proved difficult to handle, and the X-ray analyses quite challenging. A low-resolution analysis of rabbit serum transferrin in 1979 demonstrated the bilobal nature of the molecule (66), but it was not until 1987, with the publication of the structure of human lactoferrin (67), that full details of a transferrin... 

Versieck, J. Hoste. J., Barbier. F., Michels, H. and De Rudder, J. (1977). Simultaneous determination of iron, zinc, selenium, rubidium and cesium in serum and packed blood cells by neutron activation analysis. Clin. Chem. 23,1301. 

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