Hypoxia stimulates the production of the angiogenesis inhibitor 2-methoxyestradiol by swine granulosa cells.

We previously demonstrated the presence of 2-methoxyestradiol (2-ME) in swine follicular fluid. Present study was aimed first of all to investigate if swine granulosa cell produce 2-ME; in addition, we tried to assess a potential effect of hypoxia in modulating 2-ME output. Finally, we explored the effect of 2-ME in an angiogenesis bioassay set up in our lab. Our data show that cultured granulosa cells are able to produce 2-ME; interestingly, the secretion of the hormone appeared to be stimulated by hypoxia. Angiogenesis bioassay points out that 2-ME displays an inhibitory effect on neovascularisation. Therefore our data suggest that 2-ME could be a local effector in determining the fine tuning responsible for follicle angiogenesis. These data deserve special attention since the ovary is a valuable experimental model in angiogenesis research.

Investigation of novel sol-gel hydrophobic surfaces for desorption electrospray ionization-mass spectrometry analysis.

Sol-gel-based materials were synthesized, characterized and finally tested as solid supports for desorption electrospray ionization-mass spectrometry (DESI-MS) analysis of a mixture of compounds of different polarity. Films with thickness in the 2-4 µm range were obtained by a dip-coating process using tetraethoxysilane (TEOS) and octyltriethoxysilane (OTES) as sol-gel precursors. Three types of surface with different hydrophobic character were obtained by varying the TEOS/OTES ratio in the sol-gel mixture. Each coating was characterized by atomic force microscopy investigations, gaining insight into homogeneity, smoothness and thickness of the obtained films. To study hydrophobicity of each surface, surface free energy measurements were performed. Different DESI-MS responses were observed when different solvent mixture deposition procedures and solvent spray compositions were investigated. Results were finally compared to those obtained by using commercial polytetrafluoroethylene-coated slides. It was found that surface free energy plays an important role in the desorption/ionization process as a function of the polarity of analytes.

A voltammetric immunosensor based on nanobiocomposite materials for the determination of alpha-fetoprotein in serum.

The development of a voltammetric immunosensor for determination of alpha-fetoprotein (AFP) in serum is presented. ELISA assays with voltammetric reading were carried out exploiting the peculiar properties of nanobiocomposite materials based on gold nanoparticles for the immobilization of Antibody (Ab)/Antigen/Antibody-HRP (Horseradish Peroxidase) sandwich on the glassy carbon (GC) electrode surface. The electrochemical transduction was mediated by thionin, which was used in its monomeric form dissolved in the reading solution, so avoiding critical immobilization procedures. The study was aimed at the development and validation of an immunosensor able to provide results in short time, simple to use, rugged and cost-effective for AFP monitoring purposes. A crucial aspect of the study was the development of an experimental protocol leading to highly standardized and consequently reproducible sensors. Two-way analysis of variance (ANOVA) was applied to study the effect of the concentration of the solutions used for the incubation of the antibodies. The sensor was validated in serum assessing stability of the immunocomplex, linearity of response, limit of detection (3.7 ng/ml) and limit of quantitation (11 ng/ml), precision (intra- and inter-sensor repeatability) and recovery rate (103%). The stability of the GC/Ab functionalized substrate was demonstrated over one month, showing variation coefficients below 5%. Experiments carried out with real samples of clinical interest evidenced that the developed immunosensor can be considered as powerful tool in cancer screening programmes.

Trends in analytical atomic and molecular mass spectrometry in biology and the life sciences.

Trends in analytical atomic and molecular mass spectrometry (MS) are reviewed here with an emphasis on problems related to biology and the life sciences. The move towards novel desorption/ionization techniques including matrix-free laser desorption-ionization MS and recent technological developments in MS imaging of elements, small molecules, and proteins are discussed. Recent developments in the interfacing of microfluidics with MS are also reviewed. Metabolic profiling, evaluation of biomarkers, pharmaceutical metabolite identification, and many related topics are addressed.

Particle-packed column versus silica-based monolithic column for liquid chromatography-electrospray-linear ion trap-tandem mass spectrometry multiallergen trace analysis in foods.

A bicarbonate buffer-based extraction method for the simultaneous analysis of five nut allergens (Ana o 2, cashew-nut; Cor a 9, hazelnut; Pru 1, almond; Ara h3/4, peanut; Jug r 4, walnut) in cereals and biscuits using liquid chromatography-electrospray-linear ion trap-tandem mass spectrometry (LC-ESI-LIT-MS(2)) was developed and validated. The method was based on our earlier published LC-MS(2)-based method in a research frame aimed at the identification and determination of hidden allergens in foods by using selective biomarker peptides. A C18 particle-packed column and a silica-based C18 monolithic column were compared in terms of chromatographic performances, such as peak shape, resolution, analysis time and selectivity. The C18 particle-packed column exhibited better performances and was further used for method development and validation. By operating under MS(2) selected reaction monitoring (SRM) acquisition mode, linearity, limits of detection (LOD) and quantitation, trueness and precision were evaluated on breakfast samples enriched with a mix of the five nuts. Good linearity of the matrix matched-calibration curves was obtained and detection limit values generally varied from 14 to 55 mg nut/kg matrix. Recoveries were in the 76±4% to 94±3% range with RSD <15%. The capabilities of LIT to perform MS(n) fragmentation was exploited to improve selectivity of the analysis, and the LC-(SRM) MS(2) method was compared in terms of LOD, linearity, precision and accuracy with a LC-(SRM) MS(3) method. Finally, both the LC-MS(2) and LC-MS(3) methods were successfully applied to the analysis of nut traces in commercially available breakfast cereals and biscuits.

Magnetic particles functionalized with PAMAM-dendrimers and antibodies: a new system for an ELISA method able to detect Ara h3/4 peanut allergen in foods.

An innovative enzyme-linked immunosorbent assay (ELISA) format based on antibody-coated magnetic micro-particles (MPs) for the sensitive detection of Ara h3/4 allergen in food is described. The immunosupport is suspended in the incubation solutions and the MPs with the captured allergen can be easily harvested on a magnet, separated from the solutions, and washed using an easy-to-use, fast and selective approach that allows its detection and quantification. Two differently coated MPs, ProteinA-Pn-b and MP-NH(2)-PAMAM G 1.5-Pn-b immunosupports, were tested. The functionalization of the MPs with PAMAM-sodium carboxylate dendrimers elicits a major stability on the immunoglobulin activity resulting in a threefold enhancement of the analytical sensitivity for the assay with respect to a ProteinA immobilization. Validation was carried out on two different matrices: corn flakes and biscuits. In the case of MP-NH(2)-PAMAM G 1.5 -Pn-b immunosupport, limit of detection was found to be 0.2 mg peanuts/kg matrix in both matrices; the linear response range was demonstrated from 2.5 to 15 mg peanuts/kg matrix by performing statistical tests (homoscedasticity and Mandel fitting tests). Good accuracy and recovery (>80 +/- 2%) were obtained. Different food samples were tested and the results were compared with those obtained with a commercially available ELISA kit. The results obtained in this work demonstrated the applicability of the immunomagnetic ELISA methods on real samples and the possibility to perform the assay with significantly reduced reagent and sample consumption.

An SPME-GC-MS method using an octadecyl silica fibre for the determination of the potential angiogenesis modulators 17beta-estradiol and 2-methoxyestradiol in culture media.

A simple and easily automable method based on solid-phase microextraction followed by gas chromatographic-mass spectrometric analysis was developed for the determination of two potential angiogenesis modulators 17beta-estradiol (17-BE) and 2-methoxyestradiol (2-MEOE) in culture media. Trifluoroacetic anhydride was used as the derivatising agent. A homemade octadecyl silica coating, characterised by a coating thickness of 72 +/- 10 microm and a good thermal stability until 250 degrees C, was prepared. Experimental design was used to optimise the extraction conditions in terms of derivatisation time, derivatisation temperature and time of extraction. As for method validation, lower limits of quantification of 0.17 and 0.015 microg/l for 17beta-estradiol and 2-methoxyestradiol, respectively, were obtained. Finally, the capabilities of the developed fibres were evaluated for the analysis of the investigated analytes developed by granulosa cells in culture media maintained under normoxic, hypoxic and anoxic conditions, in order to better elucidate their possible role in the angiogenic process. An increase of the production of both 17-BE and 2-MEOE in hypoxic and anoxic conditions seems to be related to the effect of oxygen deprivation.

Multiplexed determination of protein biomarkers using metal-tagged antibodies and size exclusion chromatography--inductively coupled plasma mass spectrometry.

A liquid-phase immunoassay was developed for the simultaneous determination of five cancer biomarker proteins: alpha-fetoprotein (AFP), human chorionic gonadotropin (hCG), carcinoembryonic antigen (CEA), ovarian tumor antigen (CA125/MUC16), and gastrointestinal tumor antigen (CA19-9). The method was based on the incubation of a serum (or tissue cytosol) with five antibodies, each labeled with a different lanthanide (Pr(3+), Eu(3+), Gd(3+), Ho(3+), and Tb(3+), respectively) followed by the specific determination of the immunocomplex formed by size exclusion chromatography with inductively coupled plasma mass spectrometric detection (SEC-ICPMS). The sensitivity of the method was comparable with that attainable by enzyme-linked immunosorbent assay (ELISA) or radioimmunoassay with the advantages of multiplexed analysis capacity, virtually no sample preparation, and sample amount consumption, ca. 3 times lower than an ELISA test. The method was validated for the analysis of the proteins in human serum and proved to be able to discriminate ovary and uterus tumor tissue samples from those of healthy subjects.

Element-tagged immunoassay with inductively coupled plasma mass spectrometry for multianalyte detection.

The multianalyte immunoassay approach is currently attracting increasing attention due to its high sample throughput, short assay time, low sample consumption and reduced overall cost per assay. This paper reviews progress in the field of multianalyte immunoassays using inductively coupled plasma mass spectrometry, as well as applications of this approach in different fields. Examples related to the combination of protein microarray technology with the multitag approach of the immunoassay ICP-MS method and to the use of ICP-MS in the field of imaging are described. A novel strategy that involves tagging antibodies for ICP-MS detection in sensitive multitag bioassays is also presented. Finally, the outlook for this promising technique is discussed.

Evaluation of Fructooligosaccharides and Inulins as Potentially Health Benefiting Food Ingredients by HPAEC-PED and MALDI-TOF MS.

This paper describes the complementarity of high-performance anion exchange chromatography coupled with pulsed electrochemical detection (HPAEC-PED) and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-TOF-MS) to evaluate commercial available fructans (fructooligosaccharides (FOS) and inulins), having different degrees of polymerization (DP) which are usually employed by food industry as functional ingredients either for their prebiotic properties or as a fat replacer, giving a fat-like mouth feel and texture. The developed HPAEC-PED methods are able to analyze FOS (fructans with DP 3-10) and inulins (DP ranging from 3 to 80) with a good resolution and relatively short retention times to evaluate structural differences between fructooligosaccharide and inulins and the possible presence of inulooligosaccharides as well as of branching. To characterize FOS and inulin at different degrees of polymerization and to assure correct molecular assignment, MALDI-TOF MS analysis was also investigated. The 2,5-dihydroxy benzoic acid (2,5-DHB) was found to be the best matrix for FOS analysis as Actilight and Raftilose P95 products, while 3-aminoquinoline (3-AQ) seems to be the best matrix for inulin with higher DP. The applicability of the optimized methods to the identification and determination of FOS contained in a symbiotic milk as well as a type of inulin added as functional ingredient to a cooked ham is demonstrated.

Selective and rapid immunomagnetic bead-based sample treatment for the liquid chromatography-electrospray ion-trap mass spectrometry detection of Ara h3/4 peanut protein in foods.

Complex matrices commonly affect the sensitivity and selectivity of liquid chromatography-mass spectrometry (LC-MS) analysis. Thus, selective sample enrichment strategies are useful particularly to analyze organic biomarkers present in low abundance in samples. A selective immunomagnetic extraction procedure to isolate trace peanut allergen protein Ara h3/4 from breakfast cereals combined with microwave-assisted tryptic digestion and liquid chromatography-electrospray ion-trap tandem mass spectrometry (LC-ESI-IT-MS/MS) measurement was developed. Using protein A-coated magnetic bead (MB) support, anti-Ara h3/4 monoclonal antibodies (Abs) were used as selective capture molecules. The results obtained by LC-ESI-IT-MS/MS in terms of limit of detection (3 mg peanuts/kg matrix) and a significantly reduced matrix effect demonstrated that the Ab-coated magnetic bead was very effective to selectively trap Ara h3/4 protein in breakfast cereals. The magnetic bead-based sample treatment followed by LC-IT-MS/MS method here developed can be proposed as very rapid and powerful confirmatory analytical method to verify the reliability of enzyme-linked immunosorbent assay (ELISA) screening methods, since the magnetic bead-LC-IT-MS/MS method combines good sensitivity to the identification capabilities of mass spectrometry.

Innovative cavitand-based sol-gel coatings for the environmental monitoring of benzene and chlorobenzenes via solid-phase microextraction.

An innovative and very selective solid-phase microextraction coating synthesized by sol-gel technology was developed for the determination of environmental pollutants such as aromatic hydrocarbons at trace levels in air, water, and soil samples. The obtained fibers, composed of quinoxaline-bridged cavitand units, were characterized in terms of film thickness, morphology, thermal stability, and pH resistance. Fibers, characterized by an average thickness of 56 +/- 6 mum, exhibited an excellent thermal stability until 400 degrees C and a very good fiber-to-fiber and batch-to-batch repeatability with RSD lower than 6%. Finally, the capabilities of the developed coating for the selective sampling of aromatic hydrocarbons were proved, obtaining LOD values in the subnanogram per liter range. Extraction efficiency at least 2-fold higher than that obtained using commercial devices was proved for chlorobenzenes sampling in river water, obtaining extraction recoveries ranging from 87.4 +/- 2.6% to 94.7 +/- 1.9%. The selective desorption of benzene in the presence of high amounts of other airborne pollutants was also demonstrated.

Innovative sol-gel coatings for solid-phase microextraction. Development of fibers for the determination of polycyclic aromatic hydrocarbons at trace level in water.

Innovative solid-phase microextraction coatings synthesized by sol-gel technology were developed for the determination of environmental pollutants, i.e. polycyclic aromatic hydrocarbons at trace level in water. The fibers obtained, based on the use of (3-aminopropyl)triethoxysilane and diethoxydiphenylsilane were characterised in terms of film thickness, porosity, thermal stability and pH resistance. An excellent thermal stability was obtained in the case of diethoxydiphenylsilane-based coating, with a negligible weight loss until 400 degrees C. A very good fiber-to-fiber and batch-to-batch repeatability was also obtained with RSD lower than 6% using a mixture of aromatic hydrocarbons in the low ng/l range. Finally, the capabilities of the developed coating for sampling polycyclic aromatic hydrocarbons in water at trace levels were proved obtaining limits of detection about twofold lower than those achieved by using the commercially available polydimethylsiloxane 7 microm fiber.

Determination of peanut allergens in cereal-chocolate-based snacks: metal-tag inductively coupled plasma mass spectrometry immunoassay versus liquid chromatography/electrospray ionization tandem mass spectrometry.

A comparison of two methods for the identification and determination of peanut allergens based on europium (Eu)-tagged inductively coupled plasma mass spectrometry (ICP-MS) immunoassay and on liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) with a triple quadrupole mass analyzer was carried out on a complex food matrix like a chocolate rice crispy-based snack. The LC/MS/MS method was based on the determination of four different peptide biomarkers selective for the Ara h2 and Ara h3/4 peanut proteins. The performance of this method was compared with that of a non-competitive sandwich enzyme-linked immunosorbent assay (ELISA) method with ICP-MS detection of the metal used to tag the antibody for the quantitative peanut protein analysis in food. The limit of detection (LOD) and quantitation of the ICP-MS immunoassay were 2.2 and 5 microg peanuts g(-1) matrix, respectively, the recovery ranged from 86 +/- 18% to 110 +/- 4% and linearity was proved in the 5-50 microg g(-1) range. The LC/MS/MS method allowed us to obtain LODs of 1 and 5 microg protein g(-1) matrix for Ara h3/4 and Ara h2, respectively, thus obtaining significantly higher values with respect to the ELISA ICP-MS method, taking into account the different expression for concentrations. Linearity was established in the 10-200 microg g(-1) range of peanut proteins in the food matrix investigated and good precision (RSD <10%) was demonstrated. Both the two approaches, used for screening or confirmative purposes, showed the power of mass spectrometry when used as a very selective detector in difficult matrices even if some limitations still exist, i.e. matrix suppression in the LC/ESI-MS/MS procedure and the change of the Ag/Ab binding with matrix in the ICP-MS method.

Mass spectrometry and hydrogen/deuterium exchange measurements of alcohol-induced structural changes in cellular retinol-binding protein type I.

To bind and release its ligand, cellular retinol-binding protein type I (CRBP) needs to undergo conformational and dynamic changes to connect the inner, solvent-shielded cavity, where retinol is found to bind, and the outside medium. Retinol dissociation in vitro is favoured by water/alcohol mixtures whose moderately low dielectric constants mimic a property characteristic of the membrane microenvironment where this process occurs in vivo. Apo- and holo-CRBP, in either water/methanol or water/trifluoroethanol (TFE) mixtures, were analyzed at equilibrium by electrospray ionization with orthogonal quadrupole time-of-flight mass spectrometry (ESI-Q-TOFMS) to identify the alcohol-induced species. The questions were asked whether the presence of alcohols affects protein dynamics, as reflected by hydrogen/deuterium (H/D) exchange monitored by continuous-labelling experiments, and to which extent retinol dissociation influences the process. With increasing methanol, at pH near neutrality, apo-CRBP exhibits a progressively more compact conformation, resulting in reduced H/D exchange with respect to the native protein in water. Retinol dissociation from the holo-protein did not promote hydrogen replacement. Similarly, in the presence of the low TFE concentration sufficient to cause retinol dissociation, the hydrogen exchange of the resulting apo-protein was not exalted. However, in contrast with the alkanol, higher TFE concentrations induced a transition of apo-CRBP to a new alpha-helix conformation capable of exchanging all available hydrogen atoms.

Antiangiogenesis in swine ovarian follicle: a potential role for 2-methoxyestradiol.

Inhibition of angiogenesis is an important new approach for cancer treatment and the research on this topic deserve special attention. 2-Methoxyestradiol (2-ME), a molecule shown to possess antiangiogenic activity, is a naturally occurring derivative of estradiol which can be potentially produced in the ovarian follicle. This study was therefore aimed firstly to asses 2-ME content in swine follicular fluid. Moreover, we evaluated the effect of this substance on VEGF production, superoxide anion generation (O(2)(-)) and superoxide dismuatase activity in granulosa cells. Our data evidence that 2-ME is present in follicular fluid where it potentially acts as a physiological inhibitor of angiogenesis by reducing VEGF production by granulosa cells: this effect could be mediated by a decrease of O(2)(-) generation.

Optimization of a rapid microwave assisted extraction method for the liquid chromatography-electrospray-tandem mass spectrometry determination of isoflavonoid aglycones in soybeans.

A very fast chromatographic separation of isoflavonoids genistein, daidzein, formononetin and biochanin A was developed on a C18 high-speed column under isocratic conditions. The method was validated in terms of detection limits, quantitation limits (LOQs), linearity and precision. LOQs in 0.04-0.2 microg/g range were calculated, making feasible the determination of these compounds of nutritional concern at trace levels. Good linearity was demonstrated over three concentration orders of magnitude for each analyte (r2 0.990-1.000). The intra-day and inter-day repeatability was evaluated in terms of relative standard deviation (RSD%) at two concentration levels for each analyte (RSD% <9%). An optimization strategy was adopted to find the best conditions for the extraction of isoflavonoid aglycones from yellow soybeans using microwave-assisted extraction. The most relevant parameters resulted to be the microwave power, the extraction time and the acid concentration, optimal values being 600 W, 1 min and 12 M, respectively. When performing sample treatment on a fortified soybean sample, high recovery percentage was obtained for both compounds (94+/-8% for daidzein and 97+/-5% (n = 4) for genistein). The concentration level at which daidzein and genistein were found in the soybean sample were 1.21+/-0.15 mg/g and 2.38+/-0.09 mg/g (n=4), respectively.

Retention indices in the analysis of food aroma volatile compounds in temperature-programmed gas chromatography: database creation and evaluation of precision and robustness.

A retention index (RI) database containing 250 volatile compounds was created on a polar stationary phase column and validated for food aroma characterisation. Precision of the retention indices (RIs) was assessed by performing replicated injections of a representative number of volatiles under the same experimental conditions: differences lower than 1 U were observed for all the compounds. Robustness was evaluated by carrying out injections of the same set of volatile compounds under different experimental conditions, i.e. program temperature, column batches and instrumentation. Excellent results were obtained with a maximum difference in the RI values of 10 U. The capabilities of the created database for food aroma characterisation were finally evaluated by analysing the volatile fractions of different food matrices such as dry sausages, cheese and bread. A great number of volatile compounds were identified in the analysed samples on the basis of their RI, thus proving the usefulness of the RI collections in the field of food analysis.

ICP-MS as a novel detection system for quantitative element-tagged immunoassay of hidden peanut allergens in foods.

A novel ICP-MS-based ELISA immunoassay via element-tagged determination was devised for quantitative analysis of hidden allergens in food. The method was able to detect low amounts of peanuts (down to approximately 2 mg peanuts kg(-1) cereal-based matrix) by using a europium-tagged antibody. Selectivity was proved by the lack of detectable cross-reaction with a number of protein-rich raw materials.

Validation and qualification: the fitness for purpose of mass spectrometry-based analytical methods and analytical systems.

The context of validation for mass spectrometry (MS)-based methods is critically analysed. The focus is on the fitness for purpose depending on the task of the method. Information is given on commonly accepted procedures for the implementation and acceptance of analytical methods as 'confirmatory methods' according to EU criteria, and strategies for measurement. Attention is paid to the problem of matrix effects in the case of liquid chromatography-mass spectrometry-based procedures, since according to recent guidelines for bioanalytical method validations, there is a need to evaluate matrix effects during development and validation of LC-MS methods "to ensure that precision, selectivity and sensitivity will not be compromised". Beneficial aspects of the qualification process to ensure the suitability of the MS analytical system are also evaluated and discussed.