Search

A direct competitive fluorescence immunoassay (dc-FIA) and a direct competitive enzyme-linked immunosorbent assay (dc-ELISA) for the screening of dimethyl phthalate (DMP) in water samples were developed. The immunoassays utilise polyclonal antibodies against DMP raised in rabbits. The anti-DMP antibodies were linked to horseradish peroxidase (HRP) and fluorescein isothiocyanate (FITC). Under the optimal experimental conditions, the dc-ELISA has a linear working range of 0.1–2000 ng/ml (R 2=0.993) with a limit of detection of 0.09 ng/ml. In the dc-FIA, the linear working range was 0.05–30 ng/ml (R 2=0.996), and the limit of detection was 0.02 ng/ml, which is approximately four-fold more sensitive than the dc-ELISA using the same antibody and coating antigen. The results show low cross-reactivity with other structurally related compounds. The proposed methods are successfully applied to determine the DMP contaminants with a simple extraction procedure, and good recoveries were obtained. [ABSTRACT FROM AUTHOR]

Estrogen receptor (ER) α expression and associated signaling is a major driver of over two-thirds of all breast cancers (BC). ER targeting strategies are typically used as a first-line therapy in patients with steroid receptor positive (SR+) disease. Secondary resistance to anti-estrogenic agents may occur with clonal expansion and disease progression. Mechanisms underlying hormone resistance are an expanding field of significant translational importance. Cross-talk with other nuclear hormones, receptors, and signaling pathways, including thyroid hormones (TH) and their receptors (THRs), have been shown to promote endocrine therapy resistance in some studies. We have shown that TH replacement therapy (THRT) was independently and significantly associated with higher rates of relapse and mortality in SR positive (+), node-negative (LN-) BC patients, whereas it showed no association with outcomes in SR negative (-) patients. LN-, SR+ patients receiving THRT and tamoxifen had the worst outcomes, suggesting a pro-carcinogenic interaction that significantly and independently shortened survival and increased mortality. Using in vivo and in vitro models, we previously showed hormonal cross-talk, altered gene signaling, target gene activation, and resistance to tamoxifen in the presence of TH. In this report, we show TH ± E2 ± tamoxifen inhibits cell cycle control signaling, reduces apoptosis, and enhances cell proliferation, tumor growth, tamoxifen resistance, and clonal expansion. Mechanistically these changes involve numerous genes and pathways, including critical cell cycle regulatory proteins and genes identified using various molecular methods. These studies facilitate a greater mechanistic understanding of the biological and molecular impact of TH on SR+ BC. [ABSTRACT FROM AUTHOR]

A highly sensitive and specific direct competitive enzyme-linked immunosorbent assay has been developed for the detection of dipropyl phthalate (DPrP) based on antibody-coating format. The specific polyclonal antibodies against DPrP raised in rabbits. The conjugates of the antigen with horseradish peroxidase (HRP) were used as the detectable probe. Under the optimal conditions, the limit of detection of the method was 0.01 ng/mL, and a good quantitative working range of 0.01–16 ng/mL (R2=0.995) was obtained. The cross-reactivities of four structurally related phthalate esters were below 12% and did not interfere significantly the analysis of DPrP. The accuracy of the immunoassay has been evaluated and validated by analyzing real and spiked leachate from plastic food contact materials. The recoveries of DPrP ranged from 85.9% to 109.4%. This developed dc-ELISA was reliable, accurate and highly sensitive. [ABSTRACT FROM PUBLISHER]