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Title:Assessment of serum cobalt binding with diseases of domestic cats
Author(s):Schnelle, Amy
Advisor(s):Solter, Philip F.
Department / Program:Pathobiology
Discipline:VMS - Veterinary Pathobiology
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):ischemia modified albumin
Abstract:Ischemia-modified albumin has been investigated for use in human medicine as a clinical marker of ischemia, with particular interest geared toward detecting patients that have chest pain due to coronary artery syndrome. The modified form of circulating albumin has a decreased ability to bind transition metals, and assays are available that measure the amount of cobalt and nickel that bind to albumin in vitro. Oxidative damage has long been a suspected component of the underlying mechanism, while more recent work suggests that increased free fatty acid binding to albumin may also play a role in altering the albumin molecule binding characteristics. This study validated a cobalt-binding assay for use in cats. Percent cobalt binding (%CB) of serum was assessed. The run-to-run coefficient of variation ranged from 2.90% to 4.37%, while within-run precision had a coefficient of variation that ranged from 2.61% to 4.04%. Day-to-day precision was 3.46%. Limited assessment of biological variation revealed minimal change. Up to three freeze-thaw cycles failed to induce clinically significant variation in cobalt binding percentages in most samples. Samples appeared stable for at least 4 hours at room temperature. Addition of conjugated bilirubin to serum was tested up to a total bilirubin concentration of 8.9 mg/dL (icteric index of 2+) and failed to have a clinically significant effect on the percent cobalt binding; however, severely hemolytic (≥4+) samples and even mildly lipemic (≥1+) samples were falsely decreased in the percent cobalt binding when compared to the unadulterated original sample. Overall, this assay appears to function reasonably well in the measurement of cobalt-binding albumin in feline serum. Percent cobalt binding of serum from healthy and diseased cats was assessed for significant physiological and pathophysiological correlations. It did not correlate with age, sex, or breed in the study population. Unsurprisingly, %CB was correlated with albumin concentration (r= 0.62, p=0.0001). Other noted correlations included red blood cell count (r= 0.24, p=0.003), hemoglobin (r= 0.29, p=0.0001), hematocrit (r= 0.283, p=0.0001), globulins (r= -0.20, p=0.01), calcium (r= 0.27, p=0.001), total bilirubin (r= -0.237, p=0.005), and absolute lymphocytes (r= 0.16, p=0.05). However, the albumin concentration was decreased in the inflammatory group, in comparison with the noninflammatory group, and, likewise, albumin was correlated with red blood cell count, hemoglobin, hematocrit, globulins, calcium, and total bilirubin. The only parameter to which %CB seemed independently linked was a very weak correlation to the absolute lymphocyte count. Percent cobalt binding and albumin concentration were decreased in cases classified as “inflammatory”, as compared with those classified as “noninflammatory”. While %CB was not correlated with any of the disease categories of this study, group numbers were small. Limitations of this study included variable sample handling, small disease group numbers, and retrospective evaluation. The consistency of the relationship between albumin concentrations, albumin-linked correlates, and the measured %CB seems to confirm the validity of the assay in measuring ischemia-modified albumin, though this study failed to show a definitive clinical relevance of the assay in cats. Prospective studies with more controlled sample handling may yield more clinically significant findings.
Issue Date:2013-05-28
Rights Information:Copyright 2013 Amy Schnelle
Date Available in IDEALS:2013-05-28
Date Deposited:2013-05

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