Background: Evaluation of patients who present to the hospital with a complaint of chest pain or other signs or symptoms suggestive of acute coronary syndrome (ACS) is time-consuming, expensive, and problematic. Recent investigations have indicated that increases in biomarkers upstream from biomarkers of necrosis (cardiac troponins I and T), such as inflammatory cytokines, cellular adhesion molecules, acute-phase reactants, plaque destabilization and rupture biomarkers, biomarkers of ischemia, and biomarkers of myocardial stretch may provide earlier assessment of overall patient risk and aid in identifying patients with higher risk of an adverse event.

has recommended that an increased cardiac troponin should be defined as a measurement above the 99th percentile value of the reference group. A total imprecision (CV) at the decision limit of <10% is recommended. However, peer-reviewed data on assay imprecision are lacking. The purpose of this study was to construct the clinically relevant imprecision profiles for each of the commercially available cardiac troponin assays. Pools of human sera containing cardiac troponin concentrations around the MI decision limit were assessed to identify the lowest concentration associated with a 10% CV. Methods: Eight serum pools targeting different concentrations of cardiac troponin (I and T) were prepared and stored at ؊70°C until usage. The cardiac troponin measurement protocol consisted of two replicates per specimen per run, and one run per day for 20 days, using two

Ghrelin, the endogenous ligand for GH secretagogue receptors, has been reported to influence acid gastric secretion and motility, but its potential gastroprotective effect is unknown. The aims of this study were 1) to examine the effects of central and peripheral administration of ghrelin on ethanol-induced gastric ulcers in conscious rats, and 2) to investigate the possible roles of nitric oxide (NO), vagal nerve, and sensory fibers in the gastric effects of ghrelin. Ghrelin was administered either intracerebroventricularly or sc 30 min before ethanol, and mucosal lesions were examined macroscopically. Additionally, rats were either treated with the inhibitor of NO synthesis N(omega)-nitro-L-arginine methyl ester (L-NAME) or underwent bilateral cervical vagotomy or capsaicin-induced sensory denervation. Conventional histology and immunohistochemistry for ghrelin, gastrin, and somatostatin were performed on gastric specimens from representative rats. Central ghrelin (4-4,000 ng/rat) dose-dependently reduced ethanol-induced gastric ulcers by 39-77%. Subcutaneous ghrelin administration (80 micro g/kg) reduced ulcer depth only. L-NAME and capsaicin, but not vagotomy, prevented the gastroprotective effect of central ghrelin (4000 ng/rat). This is the first evidence that ghrelin exerts a potent central gastroprotective activity against ethanol-induced lesions. The gastroprotective effect of ghrelin is mediated by endogenous NO release and requires the integrity of sensory nerve fibers.

B-type natriuretic peptide (BNP) is a 32 amino acid cardiacsynthesized hormone that reduces blood pressure and increases sodium excretion (1 ). Following proteolytic cleavage of proBNP, a 108-amino acid precursor, an Nterminal fragment (NT-proBNP) and BNP are released (2 ). Increased concentrations of BNP and NT-proBNP can be used clinically to monitor heart failure, but a lack of alignment between commercial BNP and NT-proBNP assays (3 ) can lead to confusion when clinicians or laboratorians compare results measured for the same analyte on different instruments. Some of this confusion arises from variable assay specificity regarding what peptides are being measured. We studied whether (a) BNP assays demonstrated crossreactivity with NT-proBNP or proBNP, and (b) whether NTproBNP assays demonstrated crossreactivity with BNP or proBNP, by using 5 commercial BNP and 3 commercial NT-proBNP assays with 2 BNP, 2 NT-proBNP, and 2 proBNP materials.The NPs studied were: Peptide Institute synthetic BNP (aa 77-108), Scios human recombinant BNP (aa 77-108), HyTest human recombinant NT-proBNP (aa 1-76), Roche modified (amidated for stabilization) synthetic NTproBNP, HyTest human recombinant proBNP (aa 1-108), and Scios glycosylated human recombinant proBNP. BNP assays evaluated were Abbott Architect, Abbott AxSYM, Bayer Centaur, Biosite Triage, and Beckman Access (Biosite assay packaged for use by Beckman). NT-proBNP assays (all based on Roche reagents) were Dade-Behring Dimension, OrthoClinical Diagnostics Vitros, and Roche Elecsys 2010. All assays, for which epitopes of the antibodies used have been previous described (3 ), were run according to the manufacturers' guidelines. BNP, NT-proBNP, and proBNP materials were diluted with normal (low NP concentration) EDTAplasma pools and lithium-heparin plasma (Dade assay only) pools, collected from healthy donors after institutional review board approval was obtained, to achieve target concentrations of 250, 500, and 1000 ng/L. Baseline BNP and NT-proBNP were quantified first in the pools and then after the pools were spiked with NP peptides. All measurements were performed in duplicate. Baseline BNP or NT-proBNP concentrations were subtracted from each spiked pool measurement. Percent crossreactivity was calculated by dividing the measured concentration for the spiked pool into the expected peptide concentration, multiplying by 100, and then averaging across all 3 expected concentrations.Recoveries and cross-reactivity percentages between peptides and BNP and NT-proBNP assays are displayed in Table 1. The BNP assays were more specific for the BNP peptides, with recovery ranging from 79% to 199%, compared to 5% to 38% cross-reactivity to the proBNP peptides and Ͻ1% to 7% cross-reactivity to the NTproBNP peptides. Similarly, the NT-proBNP assays were more specific for the NT-proBNP peptides, showing 47% to 243% recovery, with substantial crossreactivity to proBNP peptides (Ͻ1% to 249%), and no crossreactivity to the BNP peptides (Ͻ1% across all assays).This study demonstrates th...

Background:The objective of this report is to improve the quality of immunochemical measurements of B-type natriuretic peptide (BNP) and its N-terminal propeptide (NT-proBNP). The recommendations proposed are intended for use by manufacturers of commercial assays, by clinical laboratories using those assays, by clinical trial groups and research investigators, and by regulatory agencies, such as the United States Food and Drug Administration. Methods: A group of cardiac biomarker experts reviewed and abstracted the scientific literature to provide recommendations pertaining to the quality specifications for BNP/NT-proBNP assays. Results: The evidence-based recommendations encourage manufacturers to endorse and consistently follow the proposed recommendations; encourage that all package inserts for BNP/NT-proBNP immunoassays include uniform information on assay design, preanalytical performance characteristics, analytical performance characteristics, and clinical performance; and encourage regulatory agencies to adopt a minimal and uniform set of criteria for manufacturers to provide when seeking clearance for new and/or improved assays. Conclusions: These recommendations address the use of BNP and NT-proBNP as cardiac biomarkers and not their physiologic and/or pathophysiologic relevance.

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We evaluate a new assay reagent for lipase determination, based on the use of 1,2-o-dilauryl-rac-glycero-3-glutaric acid-(6'-methylresorufin) ester (DGGR) as substrate. DGGR is cleaved by lipase, resulting in an unstable dicarbonic acid ester which is spontaneously hydrolysed to yield glutaric acid and methylresorufin, a bluish-purple chromophore with peak absorption at 580 nm. The rate of methylresorufin formation is directly proportional to the lipase activity in the sample. Bile salts, colipase and calcium chloride are included to provide optimal reactivity and specificity. Analysis of total imprecision gave a coefficient of variation of between 5.7% and 9.6%. Anticoagulants, common interfering substances and carboxylesterase had no effect on the assay, but interference by increased concentrations of serum triglycerides was noted. Good correlations were obtained with turbidimetry and a coupled enzymatic method. The estimated reference interval was 6-38 U/L. The unique characteristics of the chromogenic substrate qualify the present method as an innovative approach to serum lipase analysis.