Acute toxic effects of 8‐epidiosbulbin E,a 19‐norclerodane diterpene from yam Dioscorea antaly,on medaka Oryzias latipes embryos

The fractionation of an aqueous extract of yam Dioscorea antaly from Madagascar led to the isolation of terpenoids and flavonoids. Compounds were identified on the basis of modern mass spectrometry and two‐dimensional nuclear magnetic resonance (2D‐NMR). Toxicological effects of the most abundant isolated compound, 8‐epidiosbulbin E were studied on medaka Oryzias latipes embryo‐larval development. The lethal concentration (killing 50%; LC₅₀) to embryos treated 24 h before hatching and for 3 days after hatching was estimated to be 0·56 mg ml^?1 (P< 0·05). No mortality was observed with O. latipes larvae exposed after hatching until day 4. Anatomo‐pathological studies of embryos exposed to 0·56 mg ml^?1 showed development anomalies of the central nervous system, liver, muscle and intestine. The present data thus extend the model of O. latipes embryos as a useful animal model to analyse the effects of food toxins.     

UV-induced cis-trans isomerization of zearalenone in contaminated maize

In the literature, it has been shown that the naturally occurring trans-zearalenone (ZEN) is transformed by ultraviolet irradiation to cis-ZEN. However, the practical relevance of this transformation in animal feeding remains unclear. The aim of the present preliminary investigation was to examine the effect of UV-irradiation on the concentration of trans-ZEN in a natural feed matrix at different dry matter contents to simulate the dry and wet feeding techniques usually applied in pig feeding. Four variants, air dry or wet ZEN-contaminated ground maize either irradiated or not were tested and analysed with conventional HPLC-FLD for trans-ZEN changes, which were further examined for cis-ZEN formation by HPLC-MS/MS. In conclusion, it could be shown that, under the investigated wet feed conditions, naturally occurring trans-ZEN was partially converted by ultraviolet irradiation to its cis counterpart. In contrast, the cis/trans isomerization seemed not to be relevant in dry maize. The consequence of this finding for practical liquid feeding systems for pigs requires further investigation. Additionally, an improvement of the analytical method for cis-ZEN determination is needed.     

Action of human serum on differentiation of skin in vitro. Morphological data and study of the incorporation of labeled amino acids

Epithelial-mesodermal tissue interactions have been shown to be required for normal cytodifferentiation of chick embryo skin. Six-day limb skin does not develop in a protein free chemically defined medium, but keratinization has been observed in medium containing chicken serum. In the present study the authors show that the addition of human serum may stimulate the in vitro differentiation of explants of six-day chick embryo skin. Human serum is able to support skin keratinization and this finding has been confirmed by histological and histochemical criteria. Synthesis of proteins in tissue cultures supplemented with human serum has been studied by use of labeled amino acids such as H3-Leucine and C14-Cystine. These incorporation studies show the existence of macromolecular factors in human serum which may be responsible for the observed skin differentiation.     

A contribution to the Mesochorinae (Hymenoptera: Ichneumonidae) of Turkey

We present a first account of the species of the subfamily Mesochorinae (Hymenoptera: Ichneumonidae) found in Turkey and give distributional records for 5 genera and 23 species. Among them, 3 genera (Cidaphus Förster, 1869; Mesochorella Szepligeti, 1911; Stictopisthus Thomson, 1886) and 20 species are new for the fauna of Turkey.     

Differentiation in vitro of chick-embryo skin in presence of histones. Analysis of protein synthesis in toto and of keratin in particular, with the use of labeled precursors]

Six-day limb skin from a chick embryo was cultured in vitro for seven days in a complete medium either supplemented or not with histones. At the end of the incubation period, the chick embryo skin cultured in the absence of histones was found to undergo keratinization, the converse being true for the limbs cultured in the presence of histones. In the latter, when H3-leucine and C14-cystine were added to the medium, a sharp decrease in the labeled amino acid incorporation was found.     

Attenuation of hepatic expression and secretion of selenoprotein P by metformin

High serum selenium levels have been associated epidemiologically with increased incidence of type 2 diabetes. The major fraction of total selenium in serum is represented by liver-derived selenoprotein P (SeP). This study was undertaken to test for a hypothesized effect of hyperglycemia and the antihyperglycemic drug metformin on hepatic selenoprotein P biosynthesis. Cultivation of rat hepatocytes in the presence of high glucose concentrations (25 mmol/l) resulted in increased selenoprotein P mRNA expression and secretion. Treatment with metformin dose-dependently downregulated SeP mRNA expression and secretion, and suppressed glucocorticoid-stimulated production of SeP. Moreover, metformin strongly decreased mRNA levels of selenophosphate synthetase 2 (SPS-2), an enzyme essential for selenoprotein biosynthesis. Taken together, these results indicate an influence of metformin on selenium metabolism in hepatocytes. As selenoprotein P is the major transport form of selenium, metformin treatment may thereby diminish selenium supply to extrahepatic tissues.     

Quantitative In Situ Detection of Phosphoproteins in Fixed Tissues Using Quantum Dot Technology

Detection and quantitation of phosphoproteins (PPs) in fixed tissues will become increasingly important as additional inhibitors of protein kinases enter clinical use and new disease entities are defined by molecular changes affecting PP levels. We characterize fixation conditions suitable for accurate PP quantitation that are achievable in a clinical laboratory and illustrate the utility of in situ quantitation of PPs by quantum dot (QD) nanocrystals in two models: (1) a therapeutic model demonstrating effects of a targeted therapeutic (quantitative reduction of phospho-GSK3β) in xenografts treated with enzastaurin; and (2) a diagnostic model that identifies elevated levels of nuclear phospho-STAT5 in routine bone marrow biopsies from patients with acute myeloid leukemia based on the presence of the activating FLT3-ITD mutation. Finally, we document production of a well-characterized tissue microarray of widely available cell lines as a multilevel calibrator for validating numerous phosphoprotein assays. QD immunofluorescence is an ideal method for in situ quantitation of PPs in fixed samples, providing valuable cell type–specific and subcellular information about pathway activation in primary tissues. (J Histochem Cytochem 57:701–708, 2009)