Development and analytical validation of an enzyme-linked immunosorbent assay (ELISA) for the measurement of alpha1-proteinase inhibitor in serum and faeces from cats
ABSTRACT The objective of this study was to develop and analytically validate an ELISA for the measurement of alpha(1)-proteinase inhibitor (α(1)-PI) in serum and faeces from cats. Lower detection limit, linearity, accuracy, precision, reproducibility, and reference intervals were determined. The lower detection limits were 0.02 g/L for serum and 0.04 μg/g for faeces. The observed-to-expected (O/E) ratios for serial dilutions of serum and faecal samples ranged from 100.0 to 129.7% (mean±SD: 112.2±9.9%) and 103.5 to 141.6% (115.6±12.8%), respectively. The O/E ratios for samples spiked with seven known concentrations of α(1)-PI ranged from 82.3 to 107.8% (94.7±7.6%) for serum, and 78.5 to 148.7% (96.8±18.2%) for faeces. The coefficients of variation for intra-assay and inter-assay variability were <7.9% and <12.1% for serum, and 5.3%, 11.8%, 14.2%, and 7.7%, 10.2%, 20.4% for faeces, respectively. Reference intervals were 0.6-1.4 g/L for serum and upto 1.6 μg/g for faeces. We conclude that this ELISA is sufficiently linear, accurate, precise, and reproducible for clinical evaluation.
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ABSTRACT: Idiopathic inflammatory bowel disease (IBD) and gastrointestinal lymphoma are common disorders in cats. The aim of this study was to evaluate fecal α(1)-PI concentrations, a marker of gastrointestinal protein loss, in cats with histopathological evidence of gastrointestinal inflammation or gastrointestinal neoplasia. Fecal and serum samples were obtained from 20 cats with chronic gastrointestinal disease in which endoscopic biopsies were performed. Two groups of cats were assembled based on histopathology: Group A (n=8), mild to moderate IBD; Group B (n=12), severe IBD or gastrointestinal neoplasia. Fecal α(1)-PI concentrations and serum concentrations of total protein, albumin, globulin, cobalamin, folate, pancreatic lipase immunoreactivity, and trypsin-like immunoreactivity were determined. Nineteen of the 20 diseased cats had elevated fecal α(1)-PI concentrations, ranging from 1.9 to 233.6μg/g compared to 20 healthy control cats (normal range: ⩽1.6μg/g). Fecal α(1)-PI concentrations were statistically significantly different between healthy cats and cats of Group A (median: 3.9μg/g, range: 1.3-9.2μg/g, P<0.001) or cats of Group B (median: 20.6μg/g, 4.3-233.6μg/g; P<0.001), and between cats of Groups A and B (P<0.01). Hypoalbuminemia, hypoproteinemia, and hypocobalaminemia were detected in 88%, 83%, and 56% of the diseased cats, respectively. This study suggests that increased fecal α(1)-PI concentrations in association with low serum albumin and total protein concentrations may be a common finding in cats with IBD or gastrointestinal neoplasia. Furthermore, fecal α(1)-PI concentrations appear to be higher in cats with severe IBD or confirmed gastrointestinal neoplasia when compared to cats with mild to moderate IBD.The Veterinary Journal 12/2012; DOI:10.1016/j.tvjl.2012.09.019 · 2.17 Impact Factor
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ABSTRACT: A wide variety of markers are available to assess the function and pathology of the gastrointestinal (GI) tract. This review describes some of these markers with special emphasis given to markers used in dogs and cats. Small intestinal disease can be confirmed and localized by the measurement of serum concentrations of folate and cobalamin. Fecal α1-proteinase inhibitor concentration can increase in individuals with excessive GI protein loss. A wide variety of inflammatory markers are available for a variety of species that can be used to assess the inflammatory activity of various types of inflammatory cells in the GI tract, although most of these markers assess neutrophilic inflammation, such as neutrophil elastase, calprotectin, or S100A12. N-methylhistamine can serve as a marker of mast cell infiltration. Markers for lymphocytic or eosinophilic inflammation are currently under investigation. Exocrine pancreatic function can be assessed by measurement of serum concentrations of pancreatic lipase immunoreactivity (PLI) and trypsin-like immunoreactivity (TLI). Serum PLI concentration is increased in individuals with pancreatitis and has been shown to be highly specific for exocrine pancreatic function and sensitive for pancreatitis. Serum TLI concentration is severely decreased in individuals with exocrine pancreatic insufficiency.Toxicologic Pathology 10/2013; DOI:10.1177/0192623313506793 · 1.92 Impact Factor