Characteristics of coronary artery calcium and its relationship to myocardial ischemia in Chinese patients with suspected coronary artery disease.

OBJECTIVE: This study was aimed to investigate the characteristics of coronary artery calcium (CAC) in Chinese population with suspected coronary artery disease (SCAD). METHODS: We studied 205 Chinese patients with SCAD who were subjected to combined MPI and CAC score (CACS) study on a hybrid single photon emission tomography/computed tomography (SPET/CT) scanner. RESULTS: a) Among the 205 patients 132 (64.3%) had CACS=0 and 73 (35.6%) had CACS>0. Of those with CACS>0, 58 (28.3%) had CACS of 1∼399 and 15 (7.3%) had CACS≥400. b) The prevalence of CAC and CACS increased significantly with age (P<0.05). c) Age and hypertension were independent risk factors for CAC. d) The incidence of ischemic MPI for all 205 patients was 10.6% (14/132), 19.0% (11/58) and 33.3% (5/15). For patients with CACS=0, of 1∼399 and ≥400, respectively, showing significant difference (P=0.034), and significantly increased with CACS increasing (P=0.010). The incidence of ischemic MPI increased with increasing CACS from 10.6% (CACS=0) to 33.3% (CACS≥400). e) CACS was weakly correlated or not correlated. The value of the correlation coefficient was very small, P value was less than 0.05 with ischemic MPI (r=0.164, P=0.019) but the accuracy of the presence of CAC for detecting ischemic MPI was only 65.4% (134/205). f) The area under the ROC curve was 0.615 (P<0.05, 95% CI: 0.500∼0.729). CONCLUSION: Compared with western populations, the prevalence of CAC and absolute CACS in Chinese population with intermediate likelihood of CAD was low. CACS was weakly correlated with ischemic MPI, the accuracy of the presence of CAC for predicting ischemic MPI was low. CACS was not a reliable screening tool prior to MPI in Chinese patients with SCAD.

Development of an enzyme-linked immunosorbent assay for the detection of pentachloronitrobenzene residues in environmental samples.

A competitive enzyme-linked immunosorbent assay (ELISA) for pentachloronitrobenzene (PCNB), a fungicide and chemical intermediate, was developed using a polyclonal antiserum produced against a hapten-protein conjugate of pentachlorophenoxypropionic acid-bovine serum albumin (BSA). An indirect competitive ELISA of PCNB showed an IC50 of 37 ng/mL and a limit of detection (LOD) of 7 ng/mL. The ELISA can tolerate up to 10% (v/v) methanol, 5% (v/v) acetonitrile, or 5% (v/v) acetone without significant fluctuation of Amax and IC50. The assay sensitivity showed little change in a range of pH from 6 to 8 and concentrations of 0.05-0.2 M NaCl in the assay buffer. Very low cross-reactivities were observed for some structurally related compounds except for hexachlorobenzene (12%). The average recoveries of PCNB from fortified well water, river water, and soil samples were in ranges of 88-94, 80-91, and 70-81%, respectively. The correlations between the gas chromatographic and ELISA results were excellent (r 2 >or= 0.97, slopes from 0.86 to 1.10) for those fortified samples. The ELISA is a good alternative tool for monitoring PCNB residues in environmental samples.

Application of an enzyme-linked immunosorbent assay for the detection of clenbuterol residues in swine urine and feeds.

The present study outlines applications of an enzyme-linked immunosorbent assay (ELISA) for the analysis of clenbuterol residues. Antisera were raised from rabbits immunized with diazotized clenbuterol-bovine serum albumin (BSA) conjugate. The assay was specific to clenbuterol with a half-maximum inhibition concentration (IC(50)) of 1.8 ng/mL and 2.5 ng/mL in blank swine urine and phosphate buffer solution, respectively. The assay had high cross-reactivity (86%) with mabuterol, but low with other adrenergic agonists and antagonists. The average recovery of clenbuterol, as measured with the ELISA, ranged from 90% to 112% in swine urine samples and from 86% to 95% in feeds, respectively. This new assay was compared with commercial ELISA test kits. An excellent correlation (r(2) = 0.98) between the two methods and satisfactory recoveries suggest that the new assay can be suitable for the determination of clenbuterol residues in real samples. The assay was used to analyze clenbuterol residues in 103 swine urine samples and 68 feed samples collected from northern China. Approximately 50% of the urine samples and 25% of the feed samples analyzed were found positive (concentration of clenbuterol > or = 1 ppb). The results indicate that clenbuterol was misused in some of the areas surveyed.