Erythrodiol, a natural triterpenoid from olives, has antiproliferative and apoptotic activity in HT-29 human adenocarcinoma cells

Erythrodiol is the precursor of pentacyclic triterpenic acids present in Olea Europaea. Although olive oil and some of its constituents are reported to have anticarcinogenic activities, erythrodiol has not been assessed in its cell biological functions in detail. We therefore determined its effects on cell growth and apoptosis in human colorectal carcinoma HT-29 cells. Proliferation, cytotoxicity, and apoptosis were measured by fluorescence-based techniques. Erythrodiol inhibited cell growth with an EC50 value of 48.8 +/- 3.7 microM without any cytotoxic effects in a concentration range up to 100 microM. However, exposure of cells for 24 h to 50, 100, and 150 microM erythrodiol increased caspase-3-like activity by 3.2-, 4.8-, and 5.2-fold over that in control cells. We here demonstrate for the first time that, in colon adenocarcinoma cells, erythrodiol exerts antiproliferative and proapoptotic activity.     

Untersuchung und Bewertung der Fumonisinkontamination von einheimischem und importiertem Getreide

Cereal varieties cultivated in Germany, such as wheat, rye, grain-maize, barley, and oats were analyzed for fumonisins, including also imported maize from Argentina. In a total of 410 wheat samples and 140 rye samples of two harvesting years (1993, 1994) and in random samples of barley and oats no fumonisins were detected at all. In german grain-maize of 1993, only low fumonisin contents (17–33 ng/g) were detected occasionally. Some grain-maize samples of the 1994 harvest contained significantly higher fumonisin amounts, partly up to the mg/kg-range, which obviously is due to the extremely high temperatures during summer. In some samples of variety tests of the country the fumonisin B₁ content amounted up to 4828 ng/g and the total fumonisin content (FB₁-FB₃) up to 7132 ng/g respectively. In 1994 a total of 317 native grain-maize samples was tested, of it 109 samples of German cultivation and 208 samples from variety tests of different federeal states. Maize samples from Baden-Württemberg, which are representative to the maize harvest of this state, had a fumonisin contamination of 14%, the mean value of the contaminated samples amounting to 206 ng/g. Of the imported maize from Argentina, all the investigated 21 samples had a fumonisin content (FB₁-FB₃) of 14–1106 ng/g, the mean fumonisin content amounting to 175 ng/g.

     

Hydrogen evolution reaction on Ni-Al-Mo and Ni-Al electrodes prepared by low pressure plasma spraying

The hydrogen evolution reaction was studied on vacuum plasma sprayed Ni-Al and Ni-Al-Mo electrodes in 1m NaOH and 25% KOH at 70°C. It was found that Ni-Al-Mo electrode is more active in 25% KOH whereas Ni-Al electrode was more active in 1m NaOH solutions. A.c. impedance measurements showed two semicircles on the complex plane plots. Two different equivalent models were used to explain this behaviour. The results indicate that the formation of the second semicircle is connected with the hydrogen evolution reaction.     

Increase of essential amino acids in the bovine uterine lumen during preimplantation development

Amino acids (AAs) are crucial for the developing conceptus prior to implantation. To provide insights into the requirements of the bovine embryo, we determined the AA composition of the uterine fluid. At days 12, 15, and 18 post-estrus, the uteri of synchronized pregnant and non-pregnant Simmental heifers were flushed for the analysis of 41 AAs and their derivatives by liquid chromatography-tandem mass spectrometry. The ipsilateral endometrium was sampled for quantitative PCR. In addition to a pregnancy-dependent increase of the essential AAs (P<0.01), we detected elevated concentrations for most non-essential proteinogenic AAs. Histidine (His) and the expression of the His/peptide transporter solute carrier 15A3 (SLC15A3) were significantly increased at day 18 of pregnancy in vivo. In addition, SLC15A3 was predominantly stimulated by trophoblast-derived interferon-τ in stroma cells of an in vitro co-culture model of endometrial cells. Our results show an increased concentration of AAs most likely to optimally provide the elongating pre-attachment conceptus with nutrients.     

Adsorption of hydrogen, chlorine, and sulfur atoms on α-Cr2O3(0 0 0 1) surfaces: A density functional theory investigation

Adsorption of atomic H, Cl, and S on the chromyl (CrO), oxygen (O), and chromium (Cr) terminated α-Cr₂O₃(0 0 0 1) surfaces is investigated using density functional theory (DFT). Adsorption of H is strongest on the CrO and O terminated surfaces. H preferably binds to O atoms of these surfaces. Adsorption of Cl and S atoms is strongest on the Cr terminated surface where the atoms preferably bond to Cr. Geometry preferences are explained by electronic structure analysis. Adsorption to Cr on the O terminated surface results in significant outward relaxation of the Cr atoms, causing significant bond breaking on the surface.     

Assaying sialyltransferase activity with surface plasmon resonance

Here, we describe an activity assay for sialyltransferases based on surface plasmon resonance (SPR). Different natural and synthetic oligosaccharides serving as acceptor substrates for the sialyltransferase ST3Gal-III (EC 2.4.99.6) were immobilized or synthesized on SPR chips. The chip was then exposed to different concentrations of a reaction mixture of ST3Gal-III and CMP-Neu5Ac either by injection or by external application of the reaction mixture to the chip surface. The binding of two lectins, one that specifically recognizes the unmodified acceptor, the other the sialylated oligosaccharide, was utilized to determine the extent of enzymatic turnover. In order to obtain enzymatic activities, the SPR data were correlated to data obtained from a classical radio assay. After regeneration, that is, cleavage of the sialic acid residues by using a sialidase, the chip is available for new experiments. The technique allows the rapid determination of sialyltransferase activity with only nanomolar quantities of acceptor substrates and should be of particular value in cases in which a large variety of samples, including cell lysates, have to be screened for their enzymatic activities.