Effect of growth-promoting 17ß estradiol, 19 nortestosterone and dexamethasone on circulating levels of nine potential biomarker candidates in veal calves

The use of screening methods based on the detection of biological effects of growth promoters is a promising approach to assist residue monitoring. To reveal useful effects on protein metabolism, male and female veal calves at 10 weeks of age were treated thrice with a combination of 25 mg 17ß-estradiol 3-benzoate and 150 mg 19-nortestosterone decanoate with 2 weeks intervals and finally once with 4 mg dexamethasone. Hormone-treated calves showed a significant accelerated growth rate over 6 weeks. Plasma samples of treated and control calves were analysed for immunoreactive inhibin (ir-inhibin), osteocalcin, insulin-like growth factor 1 (IGF-1), insulin-like growth factor-binding protein 2 (IGFBP-2), IGFBP-3, luteinzing hormone (LH), follicle-stimulating hormone (FSH) and prolactin using immunoaffinity assays. Hormone treatment did not affect levels of IGF-1, IGFBP-2, IGFBP-3, LH, FSH and prolactin. The concentration of circulating ir-inhibin decreased, however, significantly (P < 0.05) in bull calves upon administration of the sex steroids, whereas it remained unchanged in the female animals. Dexamethasone treatment decreased significantly (P < 0.05) circulating levels of osteocalcin in both female and male animals. Ir-inhibin and osteocalcin were, therefore, considered as candidates for a protein biomarker-based screening assay for detection of abuse of estrogens, androgens and/or glucocorticoids in cattle fattening, which is being developed in the framework of EU research project BioCop

MicroRNA 203 Expression in Keratinocytes Is Dependent on Regulation of p53 Levels by E6.

A screen of microRNA (miRNA) expression following differentiation in human foreskin keratinocytes (HFKs) identified changes in several miRNAs, including miRNA 203 (miR-203), which has previously been shown to play an important role in epithelial cell biology by regulating p63 levels. We investigated how expression of human papillomavirus type 16 (HPV16) oncoproteins E6 and E7 affected miR-203 expression during proliferation and differentiation of HFKs. We demonstrated that miR-203 expression is reduced in HFKs where p53 function is compromised, either by the viral oncoprotein E6 or by knockout of p53 using short hairpin RNAs (p53i). We show that the induction of miR-203 observed during calcium-induced differentiation of HFKs is significantly reduced in HFKs expressing E6 and in p53i HFKs. Induction of miR-203 in response to DNA damage is also reduced in the absence of p53. We report that proliferation of HFKs is dependent on the level of miR-203 expression and that overexpression of miR-203 can reduce overproliferation in E6/E7-expressing and p53i HFKs. In summary, these results indicate that expression of miR-203 is dependent on p53, which may explain how expression of HPV16 E6 can disrupt the balance between proliferation and differentiation, as well as the response to DNA damage, in keratinocytes.

Regulation of FOS by different compartmental stresses induced by low levels of ionizing radiation

We irradiated different cellular compartments and measured changes in expression of the FOS gene at the mRNA and protein levels. [H-3]Thymidine and tritiated water were used to irradiate the nucleus and the whole cell, respectively. I-125-Concanavalin A binding was used to irradiate the cell membrane differentially. Changes in FOS mRNA and protein levels were measured using semi-quantitative RT-PCR and SDS-PAGE Western blotting, respectively, Irradiation of the nucleus or the whole cell at a dose rate of 0.075 Gy/h caused no change in the level of FOS mRNA expression, but modestly (1.5-fold) induced FOS protein after 0.5 h, Irradiation of the nucleus at a dose rate of 0.43 Gy/h induced FOS mRNA by 1.5-fold after 0.5 h, but there was no significant effect after whole-cell irradiation. FOS protein was transiently induced 2.5-fold above control levels 0.5 h after a 0.43-Gy/h exposure of the nucleus or the whole cell. Irradiation of the cell membrane at a dose rate of 1.8 Gy/h for up to 2 h caused no change in the levels of expression of FOS mRNA or protein, but a dose rate of 6.8 Gy/h transiently increased the level of FOS mRNA S-fold after 0.5 h, These data demonstrate the complexity of the cellular response to radiation-induced damage at low doses. The lack of quantitative agreement between the transcript and protein levels for FOS suggests a role for posttranscriptional regulation. (C) 2000 by Radiation Research Society.

Blood levels of vitamin C, carotenoids and retinol are inversely associated with cataract in a north Indian population

PURPOSE. To examine the association of blood antioxidants with cataract.