In vitro and in vivo satietogenic effect of yeast extracts and control of food intake in rats

Yeast extracts, by their nutritional characteristics, have a high potential as a source of biologically active molecules and functional food ingredients. In this work, in vitro and in vivo satietogenic effect of yeast extracts was examined. The in vitro results obtained for the first time showed that a yeast extract strongly stimulated the secretion of cholecystokinin (CCK) from endocrine STC-1 cells. The effects obtained with this yeast extract were compared to those obtained with other food products known for their potential involvement in satiety (milk proteins, soybean). This yeast extract showed a stronger ability to stimulate CCK secretion than all other products tested. Lack of toxicity of this yeast extract was demonstrated through cell proliferation assays. In vivo, the tests in rats confirmed the satietogenic potential of this yeast extract, particularly in terms of food intake and weight loss, but also for hormone levels.     

Analysis of biostimulated microbial communities from two field experiments reveals temporal and spatial differences in proteome profiles

Stimulated by an acetate-amendment field experiment conducted in 2007, anaerobic microbial populations in the aquifer at the Rifle Integrated Field Research Challenge site in Colorado reduced mobile U(VI) to insoluble U(IV). During this experiment, planktonic biomass was sampled at various time points to quantitatively evaluate proteomes. In 2008, an acetate-amended field experiment was again conducted in a similar manner to the 2007 experiment. As there was no comprehensive metagenome sequence available for use in proteomics analysis, we systematically evaluated 12 different organism genome sequences to generate sets of aggregate genomes, or "pseudo-metagenomes", for supplying relative quantitative peptide and protein identifications. Proteomics results support previous observations of the dominance of Geobacteraceae during biostimulation using acetate as sole electron donor, and revealed a shift from an early stage of iron reduction to a late stage of iron reduction. Additionally, a shift from iron reduction to sulfate reduction was indicated by changes in the contribution of proteome information contributed by different organism genome sequences within the aggregate set. In addition, the comparison of proteome measurements made between the 2007 field experiment and 2008 field experiment revealed differences in proteome profiles. These differences may be the result of alterations in abundance and population structure within the planktonic biomass samples collected for analysis.     

Screening of veterinary drug residues in food by LC-MS/MS. Background and challenges

Regulatory agencies and government authorities have established maximum residue limits (MRL) in various food matrices of animal origin for supporting governments and food operators in the monitoring of veterinary drug residues in the food chain, and ultimately in the consumer’s plate. Today, about 200 veterinary drug residues from several families, mainly with antibiotic, antiparasitic or antiinflammatory activities, are regulated in a variety of food matrices such as milk, meat or egg. This article provides a review of the regulatory framework in milk and muscle including data from Codex Alimentarius, Europe, the U.S.A., Canada and China for about 220 veterinary drugs. The article also provides a comprehensive overview of the challenge for food control, and emphasizes the pivotal role of liquid chromatography-mass spectrometry (LC-MS), either in tandem with quadrupoles (LC-MS/MS) or high resolution MS (LC-HRMS), for ensuring an adequate consumer protection combined with an affordable cost. The capability of a streamlined LC-MS/MS platform for screening 152 veterinary drug residues in a broad range of raw materials and finished products is highlighted in a production line perspective. The rationale for a suite of four methods intended to achieve appropriate performance in terms of scope and sensitivity is presented. Overall, the platform encompasses one stream for the determination of 105 compounds in a run (based on acidic QuEChERS-like), plus two streams for 23 β-lactams (alkaline QuEChERS-like) and 10 tetracyclines (low-temperature partitioning), respectively, and a dedicated stream for 14 aminoglycosides (molecularly-imprinted polymer).     

Regulation of adiponectin and its receptors in rat ovary by human chorionic gonadotrophin treatment and potential involvement of adiponectin in granulosa cell steroidogenesis

In mammals, adiponectin and its receptors (AdipoR1 and AdipoR2) mRNAs are expressed in various tissues. However, the cellular expression and the role of adiponectin system have never been investigated in rat ovary. Here, we report the presence of adiponectin, AdipoR1 and AdipoR2 in rat ovaries, and we have investigated its role in granulosa cells. Using RT-PCR and western blot, we show that the mRNAs and proteins for adiponectin, AdipoR1 and AdipoR2 are found in the ovaries. Immunohistochemistry localized adiponectin, AdipoR1 and AdipoR2 in theca-interstitial T-I cells, corpus luteum, oocyte and less abundantly in granulosa cells. In the KGN human granulosa cell line, adiponectin mRNA and protein were undetectable; AdipoR2 was weakly expressed, whereas AdipoR1 was clearly present. Human chorionic gonadotrophin (hCG) injection (48 h) after pregnant mare serum gonadotrophin (PMSG) injection (24 h) in immature rats increased the level of adiponectin (protein) by about threefold (P < 0.05) and those of AdipoR1 by threefold (mRNA, P < 0.05) and 1.5-fold (protein, P < 0.05) in ovary, whereas the mRNA and protein levels of AdipoR2 were unchanged. Interestingly, hCG injection (48 h) after the PMSG treatment (24 h) decreased plasma adiponectin levels and increased insulin plasma levels. In vitro in primary rat granulosa cells, human adiponectin recombinant (5 microg/ml) in the presence or absence of follicle-stimulating hormone (10(-8) M, 48 h) had no effect on the steroidogenesis. However, it increased progesterone secretion (P < 0.05) by about twofold and oestradiol production (P < 0.05) by about 1.6-fold in response to insulin-like growth factor-I (IGF-I) (10(-8) M). Furthermore, it improved IGF-I-induced IGF-I receptor-beta subunit tyrosine phosphorylation and ERK1/2 phosphorylation. In basal state, human adiponectin recombinant also increased rapidly but transiently the ERK1/2, p38 and Akt phosphorylations, whereas it increased more lately the adenosine 5'-monophosphate-activated protein kinase (AMPK) phosphorylation. Thus, AdipoR1 and AdipoR2 are regulated by hCG treatment in rat ovary and adiponectin enhances IGF-I-induced steroidogenesis in granulosa cells.     

Imaging of KCa3.1 Channels in Tumor Cells with PET and Small-Molecule Fluorescent Probes

The Ca²⁺ activated K⁺ channel K_Ca3.1 is overexpressed in several human tumor cell lines, e. g. clear cell renal carcinoma, prostate cancer, non-small cell lung cancer. Highly aggressive cancer cells use this ion channel for key processes of the metastatic cascade such as migration, extravasation and invasion. Therefore, small molecules, which are able to image this K_Ca3.1 channel in vitro and in vivo represent valuable diagnostic and prognostic tool compounds. The [¹⁸F]fluoroethyltriazolyl substituted senicapoc was used as positron emission tomography (PET) tracer and showed promising properties for imaging of K_Ca3.1 channels in lung adenocarcinoma cells in mice. The novel senicapoc BODIPY conjugates with two F-atoms ( 9 a ) and with a F-atom and a methoxy moiety ( 9 b ) at the B-atom led to the characteristic punctate staining pattern resulting from labeling of single K_Ca3.1 channels in A549-3R cells. This punctate pattern was completely removed by preincubation with an excess of senicapoc confirming the high specificity of K_Ca3.1 labeling. Due to the methoxy moiety at the B-atom and the additional oxyethylene unit in the spacer, 9 b exhibits higher polarity, which improves solubility and handling without reduction of fluorescence quantum yield. Docking studies using a cryo-electron microscopy (EM) structure of the K_Ca3.1 channel confirmed the interaction of 9 a and 9 b with a binding pocket in the channel pore.     

Interlaboratory study on lipid oxidation during accelerated storage trials with rapeseed and sunflower oil analyzed by conjugated dienes as primary oxidation products

Accelerated storage tests are frequently used to assess the oxidative stability of foods and related systems due to its reproducibility. Various methods and experimental conditions are used to measure lipid oxidation. Differences between laboratories make it necessary to determine the repeatability and reproducibility of oxidation tests performed under the same conditions. The objective of the present interlaboratory study was to evaluate the outcome of a storage test for two different bulk oils, sunflower oil (SFO) and rapeseed oil (RSO), during a period of 9 weeks at 20°C, 30°C, 40°C, and 60°C. Sixteen laboratories were provided with bottled oils and conducted the storage tests according to a detailed protocol. Lipid oxidation was monitored by the formation of conjugated dienes (CD) and the activation energy (E_a) was determined for comparative purposes and statistically evaluated. An increase in CD formation was observed for both oils when the storage temperature was increased in all laboratories. The E_a,1 ranged from 47.9 to 73.3 kJ mol⁻¹ in RSO and from 27.8 to 62.6 kJ mol⁻¹ in SFO, with average values of 58.2 and 46.8 kJ mol⁻¹, respectively. The reproducibility coefficients were 10.9% and 18.2% for RSO and SFO, respectively. Practical applications: In order to compare results on oxidative stability of foods derived from different studies, the reproducibility of storage tests and methods employed to evaluate the oxidation level should be considered. This study provides fundamental data on the reproducibility of lipid oxidation under accelerated storage conditions and defines important parameters to be considered for the conduction of experiments.     

Titration of Apparent In-Cellula Affinities of Protein-Protein Interactions**

A genetic assay permits simultaneous quantification of two interacting proteins and their bound fraction at the single-cell level using flow cytometry. Apparent in-cellula affinities of protein-protein interactions can be extracted from the acquired data through a titration-like analysis. The applicability of this approach is demonstrated on a diverse set of interactions with proteins from different families and organisms and with in-vitro dissociation constants ranging from picomolar to micromolar.