The purpose of this study was to examine the validity of albumin determinations in penguin plasma by the bromcresol green (BCG) method and the gold standard of protein electrophoresis (EPH). Plasma from 96 clinically normal and abnormal penguins (Spheniscus species) was analyzed. The 2 methods did not yield equivalent results. The BCG method underestimated the albumin level in samples from normal patients (indicated by a normal albumin:globulin ratio) and overestimated the albumin level in samples from clinically abnormal penguins (indicated by a decreased albumin:globulin ratio). After EPH of plasma samples from clinically abnormal penguins samples was performed to separate albumin and globulin fractions, the globulins exhibited marked binding to the BCG dye. There were no significant differences between the variable reaction of paired serum and plasma samples when using the BCG method. These results demonstrated marked differences in the determination of albumin levels when using the BCG method and protein EPH. They further demonstrated that the BCG method can provide erroneous results, which have the potential to significantly impact clinical diagnosis and treatment. This study confirmed findings from previous studies in other avian species that the BCG method yields unreliable results in avian species. It is our conclusion that the BCG method, commonly found on automated analyzers in commercial laboratories and on point-of-care analyzers, should not be used to determine albumin concentration in avian samples.
[Show abstract][Hide abstract] ABSTRACT: Petroleum can disrupt endocrine function in humans and wildlife, and interacts in particularly complex ways with the hypothalamus-pituitary-adrenal (HPA) axis, responsible for the release of the stress hormones corticosterone and cortisol (hereafter CORT). Ingested petroleum can act in an additive fashion with other stressors to cause increased mortality, but it is not clear exactly why-does petroleum disrupt feedback mechanisms, stress hormone production, or both? This laboratory study aimed to quantify the effects of ingested Gulf of Mexico crude oil on the physiological stress response of house sparrows (Passer domesticus). We examined baseline and stress-induced CORT, negative feedback, and adrenal sensitivity in house sparrows given a 1% oil or control diet (n = 12 in each group). We found that four weeks on a 1% oil diet did not alter baseline CORT titers or efficacy of negative feedback, but significantly reduced sparrows' ability to secrete CORT in response to a standardized stressor and adrenocorticotropin hormone injection, suggesting that oil damages the steroid-synthesizing cells of the adrenal. In another group of animals on the same 1% oil (n = 9) or control diets (n = 8), we examined concentrations of eight different blood chemistry parameters, and CORT in feathers grown before and during the feeding experiments as other potential biomarkers of oil exposure. None of the blood chemistry parameters differed between birds on the oil and control diets after two or four weeks of feeding, nor did feather CORT differ between the two groups. Overall, this study suggests that the response of CORT to stressors, but not baseline HPA function, may be a particularly sensitive bioindicator of sub-lethal chronic effects of crude oil exposure.
PLoS ONE 07/2014; 9(7):e102106. DOI:10.1371/journal.pone.0102106 · 3.23 Impact Factor
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