Validation of a commercial human ELISA to measure hyaluronic acid concentration in feline plasma

Our goal was to validate a human hyaluronic acid (HA) ELISA (Hyaluronic acid plus ELISA; TECOmedical Group) for use in feline plasma. Plasma from 5 healthy cats and 5 critically ill cats was used for validation of the assay. Validation methods performed included intra- and inter-assay variability, spike-and-recovery, and dilutional linearity. All measurements were performed in duplicate. The precision study revealed good intra-assay CV of 7.4–8.9%; inter-assay CV was 3.4–4.2%. Extraction efficiency via spiking tests yielded mean recovery of 89.6%. The assay met criteria for acceptable linearity using 3 serial dilutions. Our results demonstrate that this commercial HA ELISA had acceptable analytical performance using feline plasma and could be a useful tool in the veterinary clinical research setting.     

Analytical validation and clinical evaluation of a commercially available high-sensitivity immunoassay for the measurement of troponin I in humans for use in dogs

ObjectiveTo analytically validate a commercially available high-sensitivity immunoassay for measurement of cardiac troponin I (cTnI) in humans for use in dogs and to evaluate serum cTnI concentrations in healthy dogs and 3 well-defined groups of dogs with common cardiac diseases.AnimalsCanine serum samples were used for validation. 85 client-owned dogs including 24 healthy controls, 20 with myxomatous mitral valve disease, 19 with congenital heart disease, and 22 with arrhythmias.MethodsFour serum samples were used to analytically validate the ADVIA Centaur TnI-Ultra assay by assessing intra-assay variability, inter-assay variability, spiking recovery, and dilutional parallelism. Dogs were grouped based on examination, echocardiography, and additional testing as clinically indicated, and serum cTnI concentrations were compared.ResultsAnalysis of the serum samples used for validation revealed an intra-assay coefficient of variation between 3.6% and 5.7%, and an inter-assay coefficient of variation between 2.4% and 5.9%. Observed to expected ratios for spiking recovery were 97.9 ± 8.6% (mean, SD). Observed to expected ratios for dilutional parallelism were 73.0 ± 11.5% (mean, SD). Dogs with cardiac disease had significantly higher serum cTnI concentrations (P < 0.005) than healthy dogs.ConclusionsThe ADVIA Centaur TnI-Ultra's low limit of detection allows measurement of serum cTnI in the majority of dogs even with no or mild cardiac disease. Dilution of samples for measurement of values above the upper limit of detection is not reliable and therefore not recommended. Serum cTnI concentrations are significantly higher in dogs with cardiac disease compared to healthy dogs.     

Analytic validation and comparison of three commercial immunoassays for measurement of plasma atrial/A-type natriuretic peptide concentration in horses

Measurement of atrial/A-type natriuretic peptide (ANP) concentrations may be of use for assessment of cardiac disease, and reliable data on the analytic performance of available assays are needed. To assess the suitability for clinical use of commercially available ANP assays, intra-assay and inter-assay coefficient of variation and dilution parallelism were calculated for three immunoassays (RIA_Pen, RIA_Phoen, and an ELISA_Pen) using blood samples from healthy and diseased horses to cover a wide range of ANP concentrations. Further, agreement between assays was assessed using linear regression and Bland–Altman analyses. For all assays, precision was moderate but acceptable and dilution parallelism was good. All assays showed analytic performance similar to other immunoassays used in veterinary medicine. However, the results from the three assays were poorly comparable. Our study highlights the need for an optimised species-specific assay for equine samples.     

Analytical validation of a point-of-care test and an automated immunoturbidimetric assay for the measurement of canine C-reactive protein in serum

C-reactive protein (CRP) is an acute phase protein, which is used to evaluate and monitor the response of the innate immune system to a variety of inflammatory processes in the dog. The purpose of this study was to analytically validate a point-of-care assay (IDEXX Catalyst CRP Test) and an immunoturbidimetric assay (Gentian Canine CRP Immunoassay) for the measurement of serum CRP concentrations in dogs. These 2 assays (Catalyst, Gentian) were compared to a previously validated enzyme-linked immunosorbent assay (Tridelta Development EIA Canine CRP Assay). Linearity, precision, reproducibility, and accuracy were assessed using leftover serum samples. Agreement between assays was assessed using leftover serum samples and serum from clinically healthy dogs. Observed to expected ratios (O/E) for dilutional parallelism were 83.9 to 163.1% and 108.3 to 160.6% for the Catalyst and the Gentian assays, respectively. Coefficients of variation for intra-assay variability ranged from 6.4 to 9.5% for the Catalyst assay and 1.5 to 2.6% for the Gentian assay. Coefficients of variation for inter-assay variability ranged from 3.8 to 18.2% for the Catalyst assay and 4.5 to 5.8% for the Gentian assay. The mean O/E for recovery were 97.9% and 98.5% for the Catalyst and Gentian assays, respectively. Correlations between assays were as follows: Catalyst and Tridelta (R² = 0.76), Gentian and Tridelta (R² = 0.79), and Catalyst and Gentian (R² = 0.98). The Catalyst and Gentian assays are both acceptable for measuring CRP in dog serum, but their results are not directly comparable with the Tridelta assay.     

Development and analytical validation of a radioimmunoassay for the measurement of feline pancreatic lipase immunoreactivity in serum

Pancreatitis is recognized as an important cause for morbidity and mortality in cats, but diagnosis remains difficult in many cases. As a first step in trying to identify a better diagnostic tool for feline pancreatitis the objective of this project was to develop and analytically validate a radioimmunoassay for the measurement of feline pancreatic lipase immunoreactivity (fPLI). Feline pancreatic lipase (fPL) was purified from pancreatic tissue and antiserum against fPL was raised in rabbits. Tracer was produced by iodination of fPL using the chloramine T method. A radioimmunoassay was established and analytically validated by determination of sensitivity, dilutional parallelism, spiking recovery, intra-assay variability, and interassay variability. A control range for fPLI in cat serum was established from 30 healthy cats using the central 95th percentile. The sensitivity of the assay was 1.2 microg/L. Observed to expected ratios for serial dilutions ranged from 98.8% to 164.3% for 3 different serum samples. Observed to expected ratios for spiking recovery ranged from 76.9% to 147.6% for 3 different serum samples. Coefficients of variation for intra- and interassay variability for 4 different serum samples were 10.1%, 4.5%, 2.2%, and 3.9% and 24.4%, 15.8%, 16.6%, and 21.3%, respectively. A reference range for fPLI was established as 1.2 to 3.8 microg/L. We conclude that the assay described is sensitive, accurate, and precise with limited linearity in the lower and limited reproducibility in the lower and higher end of the working range. Further studies to evaluate the clinical usefulness of this assay are needed and in progress.     

Development and validation of a radioimmunoassay for the measurement of canine pancreatic lipase immunoreactivity in serum of dogs

OBJECTIVE: To develop and validate a radioimmunoassay (RIA) for measuring canine pancreatic lipase immunoreactivity (cPLI) in serum obtained from dogs. SAMPLE POPULATION: Serum samples from 47 healthy dogs. PROCEDURES: Canine pancreatic lipase (cPL) was purified from pancreatic specimens of dogs. Antibodies against cPL were raised in rabbits and purified by use of affinity chromatography. A tracer was produced by iodination of cPL with 125I. An RIA was established and validated by determination of sensitivity, working range, dilutional parallelism, spiking recovery, and intra- and interassay variability. A reference range for cPLI in serum was established by use of the central 95th percentile for samples obtained from 47 healthy dogs. RESULTS: Sensitivity and upper limit of the working range were 0.88 and 863 microg/L, respectively. Observed-to-expected ratios for serial dilutions ranged from 84.9 to 116.5% for 4 samples. Observed-to-expected ratios for spiking recovery ranged from 82.8 to 128.6% for 4 samples. Coefficients of variation for intra-assay variability for 4 serum samples were 18.3, 4.2, 3.5, and 8.9%, whereas interassay coefficients of variation were 29.2, 6.2, 3.9, and 4.4%, respectively. The reference range was 4.4 to 276.1 microg/L. CONCLUSIONS AND CLINICAL RELEVANCE: We conclude that the RIA described is sensitive, linear, accurate, precise, and reproducible, with limited accuracy in the high end of the working range and limited precision and reproducibility in the low end of the working range. Additional studies are needed to evaluate whether this degree of accuracy, precision, and reproducibility will negatively impact clinical use of this assay.     

Evaluation and comparison of two immunoturbidimetric assays for the heterologous determination of porcine serum C-reactive protein

The objective was first to evaluate the performance (intra- and inter-assay imprecision, inaccuracy, detection limit and overlap performance) of two different commercially available human C-reactive protein (CRP) immunoturbidimetric assays (TIA) applied to porcine serum CRP; and secondly to investigate inter-laboratory discrepancies and the influence of calibration materials when comparing results. The intra-laboratory performance seemed acceptable for clinical purposes for both assays with excellent overlap performance, acceptable detection limits, no significant inaccuracies and low imprecision. Although a significant discrepancy in the measured CRP levels was observed when comparing results, the methods agreed significantly on diagnostic classification, suggesting a low clinical significance. Both assays performed reliably for the heterologous determination of porcine serum CRP for clinical purposes. The results emphasise the need to establish species-specific standards to decrease inter-laboratory discrepancies.     

Development and analytic validation of an enzyme-linked immunosorbent assay for the measurement of canine pancreatic lipase immunoreactivity in serum

Recently, a radioimmunoassay (RIA) for measurement of canine pancreatic lipase immunoreactivity (cPLI) in serum was developed and validated. However, RIAs require frequent use of radioactive materials. Therefore, the goal of this project was to develop and validate an enzyme-linked immunosorbent assay (ELISA) for cPLI. After purifying cPL, we developed and purified antiserum against cPL in rabbits. The purified antibody was bound to microtitre plates and used to capture antigen. A portion of the purified antibody was biotinylated and used to identify the captured antigen. Streptavidin labelled with horseradish peroxidase and a horseradish peroxidase substrate were used for detection. The assay was validated by determination of sensitivity, working range, linearity, accuracy, precision, and reproducibility. The reference interval for serum cPLI was determined by the central 95th percentile in 74 clinically healthy dogs: 2.2 to 102.1 μg/L. The sensitivity and the upper limit of the working range were 0.1 and 999.2 μg/L, respectively. The ratios of observed to expected values for dilutional parallelism for 6 serum samples ranged from 0.0 to 148.8%; the ratios for spiking recovery for 4 serum samples ranged from 90.4 to 112.6%, assuming 55% recovery of the cPL. Coefficients of variation for intra- and interassay variability for 6 different serum samples were 2.4, 3.4, 4.1, 5.8, 7.4, and 10.0% and 5.9, 7.7, 11.6, 13.9, 23.5, and 46.2%, respectively. We conclude that the ELISA described here is sufficiently sensitive, linear, accurate, precise, and reproducible for clinical application. Evaluation of its clinical usefulness for the diagnosis of exocrine pancreatic disorders in dogs is under way.     

Purification and partial characterization of canine neutrophil elastase and the development of an immunoassay for the measurement of canine neutrophil elastase in serum obtained from dogs

OBJECTIVE: To purify neutrophil elastase (NE) from dog blood and develop and validate an ELISA for the measurement of canine NE (cNE) in canine serum as a marker for gastrointestinal tract inflammation. SAMPLE POPULATION: Neutrophils from 6 dogs immediately after they were euthanatized and serum from 54 healthy dogs. PROCEDURES: cNE was purified from blood by use of dextran sedimentation, repeated cycles of freezing-thawing and sonication, cation-exchange chromatography, and continuous elution electrophoresis. Antibodies against cNE were generated in rabbits, and an ELISA was developed and validated by determination of sensitivity, dilutional parallelism, spiking recovery, intra-assay variability, and interassay variability. A reference range was established by assaying serum samples from the 54 healthy dogs and by use of the lower 97.5th percentile. RESULTS: cNE was successfully purified from blood, and antibodies were successfully generated in rabbits. An ELISA was developed with a sensitivity of 1,100 mug/L. The reference range was established as < 2,239 mug/L. Ratios of observed-to-expected results for dilutional parallelism for 4 serum samples ranged from 85.4% to 123.1%. Accuracy, as determined by spiking recovery, ranged from 27.1% to 114.0%. Coefficient of variation for 4 serum samples was 14.2%, 16.0%, 16.8%, and 13.4%, respectively, for intra-assay variability and 15.4%, 15.0%, 10.5%, and 14.6%, respectively, for interassay variability. CONCLUSIONS AND CLINICAL RELEVANCE: The purification protocol used here resulted in rapid and reproducible purification of cNE with a high yield. The novel ELISA yielded linear results and was accurate and precise. Additional studies are needed to evaluate the clinical usefulness of this assay.     

Development and validation of a method for simultaneous separation and quantification of 5 different sugars in canine urine.

The objective of this project was to develop and validate a method for concurrent separation and quantification of methylglucose, rhamnose, xylose, sucrose, and lactulose in canine urine by using high pressure anion exchange liquid chromatography and pulsed amperometric detection. The method was validated by evaluating dilutional parallelism, spiking recovery, intra-assay variability, and inter-assay variability. Observed to expected ratios for 3 urine samples, and all sugars, ranged from 77.6% to 106.9% for a 1:2 dilution, 85.2% to 121.4% for a 1:4 dilution, and 91.6% to 163.7% for a 1:8 dilution. Observed to expected ratios for spiking recovery of 3 urine samples, all sugars, and 5 different spiking solutions, ranged from 85.5% to 116.7 % (mean +/- SD, 100.5 +/- 6.0%). The intra-assay coefficients of variation were 1.6%, 3.4%, and 4.7% for methylglucose; 1.6%, 2.0%, and 3.6% for rhamnose; 2.7%, 1.4%, and 1.1% for xylose; 9.8%, 3.4%, and 4.0% for sucrose; and 3.2%, 3.3%, and 3.3% for lactulose. Inter-assay coefficients of variation were 3.2%, 5.7%, and 4.2% for methylglucose; 4.3%, 5.4%, and 6.4% for rhamnose; 3.3%, 5.0%, and 4.2% for xylose; 9.4%, 9.9%, and 9.4% for sucrose; and 6.1%, 4.9%, and 2.7% for lactulose. In conclusion, a method for simultaneous separation and quantification of 5 sugars in canine urine was established and found to be linear, accurate, precise, and reproducible. This method may prove useful in the simultaneous evaluation of gastric permeability, small intestinal permeability, and small intestinal mucosal function in dogs with gastrointestinal disorders.     

Clinical validation of a proANP 31-67 fragment ELISA in the diagnosis of heart failure in the dog

Atrial natriuretic peptide (ANP) is a polypeptide hormone found in increased concentrations in the plasma of dogs with heart failure. However, problems arise in using ANP as a diagnostic marker for heart failure because of its short half-life in plasma, proteolysis post-collection and the necessity for a radioimmunoassay. The diagnostic utility of a proANP 31-67 ELISA for the detection of heart failure in dogs was evaluated using plasma collected from 31 dogs with clinical and radiographic signs of heart failure and control samples from 40 dogs considered to be free of cardiac disease. Log proANP 31-67 levels were significantly higher in the heart failure group (P < 0.001). In this population of dogs, using a cut-off value of 1,750 fmol/ml, the sensitivity and specificity of the assay were 83.9 per cent and 97.5 per cent, respectively. Using a cut-off of 1,350 fmol/ml, the sensitivity and specificity were 93.5 per cent and 72.5 per cent, respectively. It is concluded that a proANP 31-67 fragment ELISA should prove to be a useful diagnostic aid in naturally occurring canine heart failure.     

Development and analytic validation of an immunoassay for the quantification of canine S100A12 in serum and fecal samples and its biological variability in serum from healthy dogs

S100A12 (calgranulin C) is a Ca(2+)-binding protein that has been proposed to play a central role in both innate and acquired immune responses. In humans, S100A12 has been reported to be increased in serum and/or plasma in patients with various inflammatory disorders, and this protein has been suggested to be a sensitive and specific marker for inflammatory bowel disease (IBD). An immunoassay for S100A12 is currently available for use in humans, but antibodies against the human protein do not cross-react with canine S100A12 (cS100A12). Both sensitive and specific markers for canine patients with systemic or localized inflammatory diseases are currently lacking, thus the aim of this study was to develop and analytically validate a radioimmunoassay (RIA) for the quantification of cS100A12 in serum and fecal specimens and to determine the biological variation of cS100A12 in serum from healthy dogs. A competitive liquid-phase RIA was developed and analytically validated by determining assay working range, dilutional parallelism, spiking recovery, and intra- and inter-assay variability. Reference intervals for serum and fecal concentrations of cS100A12 were established from 124 and 65 healthy dogs, respectively, and components of variation for serum cS100A12 were determined from 11 dogs over 2.6 months. The working range of the assay was 0.6-432.7 μg/L. No cross-reactivity was observed with the cS100A8/A9 protein complex, the closest structural analogues available. Observed-to-expected ratios (O/E) for the serial dilution of serum and fecal extracts ranged from 97.2 to 146.8% and from 75.3 to 129.8%, respectively. O/E for spiking recovery for serum and fecal extracts ranged from 87.8 to 130.4% and from 84.8 to 143.8%, respectively. Coefficients of variation (CV) for intra- and inter-assay variability for sera were ≤ 8.1% and ≤ 7.8%, respectively, and were ≤ 7.8% and ≤ 8.7%, respectively, for fecal extracts. Reference intervals for serum and fecal cS100A12 were 33.2-225.1 μg/L and <24-745 ng/g, respectively. For biological variability testing, analytical, intra-individual, inter-individual, and total CV were 5.7, 29.2, 31.2, and 66.0%, respectively, yielding an index of individuality of 0.95 and a minimum critical difference (p<0.05) for sequential values of 84.9%. The RIA for cS100A12 measurement described here is analytically sensitive and specific, linear, accurate, precise, and reproducible, and will facilitate further research into the clinical utility of quantifying serum and fecal cS100A12 in canine patients with inflammatory diseases. Moderate changes in serum cS100A12 concentrations may be clinically relevant; however, the use of a population-based reference interval may require caution.     

Measurements of plasma endothelin immunoreactivity in healthy cats and cats with cardiomyopathy

Plasma concentrations of endothelin-1 (ET-1), the most potent endogenous pressor substance discovered to date, are abnormally high in humans with congestive heart failure (CHF), and they correlate with the degree of functional impairment. We sought first to validate a human sandwich ELISA kit that targets that portion of the amino acid sequence that is identical in cats. The assay demonstrated linearity (R2 = .9968) and parallelism (P = .5339), recovery of spiked human ET-1 in cat plasma averaged 98.7%, and intraassay precision had a coefficient of variation <10%. We subsequently determined ET-1 immunoreactivity in healthy cats and in cats with myocardial disease with and without CHF, systemic thromboembolism (STE), or both. Plasma ET-1 immunoreactivity was measured in 12 healthy cats and in 28 cats with primary myocardial disease, including hypertrophic cardiomyopathy (HCM), dilated cardiomyopathy (DCM), or restrictive or unclassified cardiomyopathy (RCM and UCM), respectively. Plasma ET mean (95% CI) concentrations were 0.777 (0.6536-0.924) fmol/mL in the control cats, 1.427 (0.922-2.209) fmol/mL in 12 cats with cardiomyopathy (HCM = 11, RCM/UCM = 1) but without CHF or evidence of STE, and 2.360 (1.666-3.343) fmol/mL in 16 cats with cardiomyopathy (HCM = 8, RCM/UCM = 7, DCM = 1) and CHF (n = 15) or STE (n = 4). Plasma immunoreactivity of ET-1 was significantly higher in cats with myocardial disease without CHF/STE versus normal cats (P < .05) and in cats with myocardial disease with CHF/STE versus normal cats (P < .001).     

The diagnostic relevance of NT‐proBNP and proANP 31–67 measurements in staging of myxomatous mitral valve disease in dogs

Background

There is no agreement in current publications regarding the reliability of serum concentrations of natriuretic peptides (NPs) to detect dogs with subclinical myxomatous mitral valve disease (MMVD) and to differentiate between asymptomatic stages.

Objectives

We sought to compare N‐terminal pro‐B‐type natriuretic peptide (NT‐proBNP) and pro‐atrial natriuretic peptide 31‐67 (proANP) concentrations between various stages of canine MMVD and to investigate the influence of age, weight, and sex.

Methods

In this prospective study, dogs were classified in different disease stages using the modified Canine Heart failure International Expert Forum (CHIEF) system. Serum NP concentrations were compared between groups.

Results

A total of 559 samples from 116 healthy dogs and 236 dogs with MMVD were analyzed. Using cut‐off values (1207 pmol/L for NT‐proBNP, 1578 fmol/mL for proANP), dogs with MMVD with and without congestive heart failure (CHF) could be differentiated with a sensitivity of 83% for both and specificities of 85% and 86%, respectively. Dogs staged in CHIEF B1 and B2 could not be distinguished based on NP concentrations due to wide variation within the groups. Intact females (means 598 pmol/L and 1036 fmol/mL, respectively) had significantly higher values of both NPs than intact males (315 pmol/L and 836 fmol/mL).

Conclusions

NPs in canine MMVD are useful to discriminate between asymptomatic dogs and dogs with CHF. Due to a large overlap of NP‐concentrations between the groups, NPs do not seem to be useful to differentiate between dogs in stages B1 and B2. Interpretation of NT‐proBNP and proANP values should include consideration of sex‐specific differences.     

Serum Levels of Cardiac Markers NT‐proANP and NT‐proBNP in Brachycephalic bitches at Different Gestational Stages

The aim of this study was to determine serum levels of natriuretic peptide precursors (NT‐proANP and NT‐proBNP) during pregnancy in brachycephalic bitches. Fifteen healthy multiparous bitches were selected for this prospective study. Serum levels of NT‐proANP and NT‐proBNP were measured during anoestrous and at 14, 35, 42, 49 and 56 days (2nd, 5th, 6th, 7th and 8th weeks) of pregnancy. Fourteen animals had normal gestations, and one bitch developed single foetus syndrome. The natriuretic peptide levels of this animal were not included in this study; however, it is important to report that its NT‐proANP levels were four times greater than those of normal patients. There was no significant difference (p = 0.072) in NT‐proBNP levels between anoestrous (0.20 ± 0.10 ng/ml) and the different pregnancy weeks (0.27 ± 0.12 ng/ml). There was a positive correlation (p < 0.0001) between NT‐proANP and gestational age, and the levels of this marker increased significantly (p < 0.0001) during the 6th (0.26 ± 0.06 ng/ml), 7th (0.28 ± 0.04 ng/ml) and 8th weeks (0.29 ± 0.05 ng/ml) when compared to anoestrous (0.18 ± 0.02 ng/ml). NT‐proANP serum levels are correlated with gestational development and may be indicative of cardiovascular adaptation in canine brachycephalic pregnancy.     

内皮素-1对肉鸡腹水综合征发生发展的影响

利用放射免疫分析方法，分别测定了35日龄正常组、轻度腹水组、重度腹水组肉鸡血浆内皮素-1（ET-1）、心钠素（ANP）的含量以及心、肝、肺、肾等组织ET-1的含量，并测定了腹水心脏指数（AHI）、平均右心室压（mRVP）和平均肺动脉压（mPAP）；同时还用硝酸还原酶法测定了血清中一氧化氮（NO）的水平。结果发现，随腹水程度的加深，mRVP、mPAP、AHI极显著（P〈0．01）升高，肉鸡血浆ET-1、ANP和组织中ET-1的含量以及血清NO浓度也显著（P〈0．05）或极显著（P〈0．01）升高，且重度腹水组高于轻度腹水组；另外还发现，血浆ET-1、ANP与mPAP、AHI以及心脏ET-1含量之间相关性显著（P〈0．05），而血清NO含量与上述指标之间无明显的相关性（P〉0．05）。结果表明ET-1、ANP、NO均参与了肉鸡AS的发生和发展过程并在其中起着重要作用，其中ET-1、ANP与肉鸡发生腹水的程度有密切的关系。     

鸡血浆中乙酰氨基阿维菌素HPLC检测法的建立及口服给药后的药代动力学研究

旨在建立鸡血浆中乙酰氨基阿维菌素（EPR）浓度的高效液相色谱（HPLC）检测方法,并进行EPR在鸡体内的药代动力学研究。用甲醇提取血浆中的EPR,并用Sep-Pak C18固相萃取法进行纯化,纯化后的EPR经干燥处理,用三氟乙酸酐和N-甲基咪唑对其进行衍生化,使用荧光HPLC检测。结果表明,在血浆EPR含量为0.1~100 ng/mL范围内,标准曲线线性关系良好,相关系数r=0.9999。检测限（LOD）为0.1 ng/mL,定量限（LOQ）为0.3 ng/mL。批内批间的平均回收率均大于90%,批内变异系数2.81~8.02%,批间变异系数4.32~5.83%。给蛋鸡口服5.0 mg/kg的EPR,EPR在鸡体内的药代动力学参数显示：给药后1.58 h可达最大血药浓度（Cmax）354.27 ng/mL;消除半衰期（T1/2el）为5.52 h;平均滞留时间（MRT）为6.40 h。以上结果说明建立的检测方法灵敏度高、准确度高,干扰少,适用于鸡血浆中EPR含量的检测。药代参数提示EPR在鸡体内的吸收代谢迅速,可较快消除。     

裙带菜膳食纤维对高脂血症大鼠体内内皮素-1水平的影响

目的：研究裙带菜可溶性膳食纤维对体内内皮素－1水平的影响。方法：40只大鼠分为4组（n=10）：正常对照组、高脂模型组、膳食纤维低剂量组（5％）、膳食纤维高剂量组（10％）;经裙带菜可溶性膳食纤维处理8W后,检测血浆内皮素－l（ET－1）水平,并用RT－PCR检测内皮素－1（ET－1）mRNA表达水平。结果：裙带菜可溶性膳食纤维显著降低ET－1水平并伴随着（ET－1）mRNA表达下调。结论：裙带菜可溶性膳食纤维能降低高脂血症大鼠血浆ET－l的水平,这可能与ET－1mRNA表达水平的下调有关。     

Endothelin response during and after exercise in horses

The objective of the present study was to measure plasma endothelin-1 (ET-1) at rest and during exercise in the horse. Six healthy, Standardbred and Thoroughbred mares (5.3+/-0.8 years; 445.2+/-13.1 kg) which were unfit, but otherwise accustomed to running on the treadmill, were used in the study. Plasma ET-1 concentrations were measured using a commercially available radioimmunoassay kit. Horses performed three trials: a standing control (CON) trial where blood was collected from the jugular vein every minute for 5 min; a graded exercise test (GXT) where blood samples were collected at the end of each 1 min step of an incremental exercise test; and a 15 min submaximal (60% VO(2max)) steady-state exercise test (SST) where blood samples were collected 1 min before, immediately after, and at 2 min, 10 min and 20 min post-exercise. Plasma ET-1 concentration did not change (P>0.05) during the CON trial where it averaged 0.18+/- 0.03 pg/mL (mean+/-SE). Surprisingly, plasma ET-1 concentration did not change during the GXT trial where it averaged 0.20+/-0.03 pg/mL. There were no differences between the mean concentrations obtained in either trial (P>0.05). Plasma ET-1 concentrations were, however, significantly elevated (P<0.05) immediately following exercise and at 2 min post-exercise in the SST. Post-exercise plasma ET-1 concentrations returned to baseline (P>0.05) by 10 min of recovery. Together, these data may suggest that ET-1 concentrations are altered in response to an exercise challenge.     

Development and analytical validation of an enzyme linked immunosorbent assay for the measurement of canine gastric lipase immunoreactivity in serum

The objective of this study was to develop and analytically validate an enzyme linked immunosorbent assay (ELISA) for measurement of canine gastric lipase immunoreactivity (cGLI). A sandwich ELISA was developed using canine gastric lipase (cGL) purified from canine stomachs and polyclonal antibodies directed against cGL, raised in rabbits and purified by affinity chromatography. The assay was validated by determination of sensitivity, working range, linearity, accuracy, precision, reproducibility, and the upper limit of the control range by determining the 97.5th percentile of serum cGLI concentration in 74 healthy canines. Sensitivity and working range in serum were 200 ng/L and 200 to 39 160 ng/L, respectively. Observed to expected ratios for dilutional parallelism for 3 serum samples and 3 dilutions ranged from 86.1% to 244.2% (mean +/- standard deviation [s]; 125.4% +/- 48.2%). Observed to expected ratios for spiking recoveries for 3 serum samples and 6 spiking concentrations ranged from 66.4% to 152.5% (mean +/- s; 104.5% +/- 22.9%). Intra-assay and interassay variabilities for 3 different serum samples were 25.5%, 9.4%, and 13.4% and 26.0%, 17.2%, and 14.4%, respectively. The upper limit of the control range for serum cGLI was 662 ng/L. We concluded that the ELISA for cGLI described here is highly sensitive and shows a wide working range. However, the validation characteristics for this assay are suboptimal and below values of approximately 2.000 ng/L the assay is more semiquantitative in nature. Despite its limitations, whether this assay is useful for the diagnosis of canine gastric disorders remains to be determined.