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The Social Security earnings test reform in 2000 eliminated the earnings test for all individuals between the normal retirement age (NRA) and age sixty-nine. The earnings test has long been accused of imposing a disincentive on the labor supply among older workers. In this article, we argue that the policy change may also have affected the labor supply among people who were just below the NRA around 2000. We utilize approaches embedded with a difference-in-differences design to estimate the anticipation effect on the labor supply of the slightly younger group (aged sixty-two to sixty-four) using an even younger cohort as the control group. Our preferred estimates indicate that the cohort aged sixty-two to sixty-four had worked 5.4 percent more weeks per year and 5.1 percent more hours per week after the earnings test reform in 2000. [ABSTRACT FROM AUTHOR]

Polyclonal and monoclonal antibodies against valnemulin, a new semi-synthetic antibiotic derivative of pleuromutilin administered to treat swine dysentery and pneumonia, were generated. To achieve high enzyme-linked immunosorbent assay sensitivity for valnemulin, several heterologous coating antigens were prepared and evaluated, differing in the length of the spacer arm and the conjugation site between valnemulin and carrier protein. After the optimisation of immuno-reagents dilution, the enzyme-linked immunosorbent assay, based on polyclonal antibody number 2 and one heterologous coating antigen, showed the highest sensitivity with an IC50value for valnemulin of 0.96 ng/mL in buffer. For spiked porcine liver, an extraction procedure with a mixture of acetonitrile and 0.01 M hydrochloric acid (40:60 v/v) was proposed and no further sample pre-treatment other than 10 times dilution of the extract was necessary prior to analysis, which gave recovery values ranging from 75.7% to 89.4%. The dynamic assay range and the limit of detection of the assay were 2.4−49.9 and 1.67 µg/kg for porcine liver, respectively. The assay was compared with a confirmation method based on LC-MS/MS by using valnemulin-treated samples, and a satisfactory correlation between both methods was observed. [ABSTRACT FROM PUBLISHER]

Abstract: Fumonisin B1 (FB1) is a mycotoxin, mainly produced by Fusarium fungi and present in food and feed. It causes harmful effects on human and animal health. Therefore, it is necessary to develop sensitive and reliable screening methods. In this study, a highly sensitive monoclonal antibody (MAb) against FB1, clone 2D7, was produced, and the 50% inhibition concentration (IC50) of the MAb was 2.2 ng/mL in buffer. The MAb showed high cross-reactivity with fumonisin B2 (FB2), and negligible cross-reactivity with other mycotoxins. A sensitive indirect competitive enzyme-linked immunosorbent assay (icELISA) based on this MAb was developed for the determination of FB1 in maize. In spiked samples (100, 200 and 500 μg/kg), the average recoveries ranged from 78 ± 11 to 107 ± 4%, and the coefficient of variation ranged from 3 to 15%. The limit of detection of the icELISA was 5.4 μg/kg. This method was compared to liquid chromatography tandem mass spectrometry (LC–MS/MS) using naturally contaminated samples, and the correlation coefficient was above 0.82. These results show the reliability of the icELISA method for the determination of FB1 in maize. [Copyright &y& Elsevier]

Erythromycin is an antibiotic used extensively in veterinary practice worldwide for treatment, prevention and growth promotion. In this work, monoclonal antibodies (Mabs) against erythromycin were produced and used to develop a competitive indirect enzyme-linked immunosorbent assay (ciELISA) for the determination of erythromycin in milk. A novel carboxyphenyl derivative of erythromycin (ERO-CMO) was synthesized and conjugated with bovine serum (BSA) for use as the immunogen or ovalbumin (OVA) as the coating antigen. Four hybridoma cell lines were isolated, which produced Mabs that competed with erythromycin. The 6C1 and 5B2 Mabs had IC 50 values for erythromycin of 14.40 and 0.94 μg L − 1 , respectively. These Mabs demonstrated high cross-reactivity to the macrolides containing 14-membered rings, but not to oleandomycin. No cross-reactivity was observed for 12 macrolides that contained 15 or 16-membered lactone rings or for 2 pleuromutilins. The ciELISA developed using the 5B2 Mab afforded recovery values that ranged from 76.9% to 85.7% with only a 10-fold sample dilution prior to analysis. [ABSTRACT FROM AUTHOR]