[Sample preprocessing method for residual quinolones in honey using immunoaffinity resin].

A sample preparation method was developed for determination of quinolones in honey using immunoaffinity resin. For this purpose, an immunoaffinity resin for quinolones was prepared by coupling a quinolone-specific monoclonal antibody to agarose resin. Honey samples diluted with phosphate buffer were reacted with immunoaffinity resin. After the resin was washed, quinolones were eluted with glycine-HCl. Quinolones in the eluate were determined by HPLC with fluorescence detection. No interfering peak was found on the chromatograms of honey samples. The recoveries of quinolones from samples were over 70% at fortification levels of 20 ng/g (for norfloxacin, ciprofloxacin and enrofloxacin) and 10 ng/g (for danofloxacin). The quantification limits of quinolones were 2 ng/g. This sample preprocessing method using immunoaffinity resin was found to be effective and suitable for determining residual quinolones in honey.

Anthracycline-induced suppression of GATA-4 transcription factor: implication in the regulation of cardiac myocyte apoptosis.

Anthracyclines are effective cancer chemotherapeutic agents but can induce serious cardiotoxicity. Understanding the mechanism of cardiac damage by these agents will help in development of better therapeutic strategies against cancer. The GATA-4 transcription factor is an important regulator of cardiac muscle cells. The present study demonstrates that anthracyclines can down-regulate GATA-4 activity. Treatment of HL-1 cardiac muscle cells or isolated adult rat ventricular myocytes with anthracyclines such as daunorubicin and doxorubicin decreased the level of GATA-4 DNA-binding activity. The mechanism of decreased GATA-4 activity acts at the level of the GATA-4 gene, because anthracyclines caused significantly decreased levels of GATA-4 protein and mRNA. The rate of decline in GATA-4 transcript levels in the presence of actinomycin D was unaltered by anthracyclines, indicating that these agents may affect directly GATA-4 gene transcription. To determine whether decreased GATA-4 levels are functionally related to cardiac muscle cell death that can be induced by anthracyclines, the ability of ectopic GATA factors to rescue anthracycline-induced apoptosis was tested. Adenovirus-mediated expression of either GATA-4 or GATA-6 was sufficient to attenuate the incidence of apoptosis. Furthermore, suppression of GATA-4 DNA-binding activity by a dominant negative mutant of GATA-4 induced the apoptosis. These results suggest that the mechanism of anthracycline-induced cardiotoxicity may involve the down-regulation of GATA-4 and the induction of apoptosis.