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Fluorescence anisotropy is a homogeneous, sensitive, ratiometric, and real-time analytical technology. However, it is a great challenge to produce a large fluorescence anisotropy change upon the presence of target small molecules without nanoparticles-dependent amplification. This work reports a nanoparticle-free and multiple G-enhanced fluorescence anisotropy assay for detection of DNAzyme activity. A Pb2+-dependent GR-5 DNAzyme was used as a model. We hybridized the rA-cleavable substrate strand containing a TMR label at the 5'-end with the DNAzyme strand containing an extended three G bases at the 3'-end. By this design, we demonstrate that both fluorescence quenching and the enhanced DNAzyme activity contribute to a Pb2+-induced large fluorescence anisotropy change (/Δr/ = 0.168). The limit of detection for Pb2+ is estimated to be about 100 pM with a dynamic range from 200 pM to 100 nM. The interference from the other nine divalent metal ions of 1000-times excess amount is negligible. Moreover, we show an extended assay for evaluation of the interactions of Pb2+ with cysteine and glutathione by the detection of GR5 DNAzyme activity. Collectively, we developed a novel fluorescence anisotropy amplification assay, enabling us to detect DNAzyme activity and associated cofactors and inhibitors and to characterize the Pb2+-chelation capability of free thiols. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) is a heavy metal that has detrimental effects on various organs. The widespread contamination of Cd in the environment, crops and food sources poses a severe threat to human health. Acute toxicities of Cd have been extensively investigated; however, the health impact of chronic low-dose exposure to Cd, particularly exposure under non-toxic concentrations, has yet to be elucidated. Furthermore, the toxic threshold of Cd is currently unknown. Ferroportin is the only known iron exporter in vertebrate cells, and it has an essential role in controlling iron egress from cells. To the best of our knowledge, the present study is the first to verify the regulation of ferroportin by Cd. Treatment with low-dose Cd (i.e. at sublethal concentrations, without undermining cell viability) increased the protein expression of ferroportin in macrophages, and this was associated with depleted cellular iron levels. Mechanistic investigations revealed that Cd modulated the ferroportin concentration at the translational level, via the iron responsive element located at the 5'-untranslated region of ferroportin. In conclusion, these data provide evidence for the molecular basis by which Cd alters cellular iron availability through elevating concentrations of ferroportin. [ABSTRACT FROM AUTHOR]

This study was performed to characterize the bone metabolism in ten 6-month-old male Goto-Kakizaki (GK) rats, a spontaneous type 2 diabetic model, with ten age- and sex-matched non-diabetic Wistar rats as controls. The femora and the fifth lumbar vertebrae were analyzed by a dual energy X-ray absorptiometry for bone mineral density. Histomorphometrical analyses were performed on the sections from the tibia embedded in methylmethacrylate. Biomechanical characterizations were made by a three-point bending test and a compressive test on the femur and the fifth vertebral body respectively. Compared to the control rats, the bone mineral density was significantly deceased and the histomorphometrical studies showed significantly decreased trabecular bone volume, trabecular thickness and number, osteoid surface and thickness, mineralizing surface, mineral apposition rate and bone formation rate, and also a significant increase in mineralization lag time in the diabetic rats. Strength in both bones and elastic modulus of vertebral body significantly decreased in the diabetic rats as well. In addition, the serum osteocalcin levels were significantly decreased and the serum tartrate-resistant acid phosphatase activity was significantly increased. In conclusion, the 6-month-old GK diabetic rats developed osteopenia with an increased risk of fracture owing to the decreased bone formation, and might be a useful model for unraveling the effects of diabetes on bones independent of obesity frequently seen in the type 2 diabetic patients. [ABSTRACT FROM AUTHOR]