Direct detection of peptides and small proteins in fingermarks and determination of sex by MALDI mass spectrometry profiling.

Matrix Assisted Laser Desorption Ionisation Mass Spectrometry (MALDI MS) can detect and image a variety of endogenous and exogenous compounds from latent fingermarks. This opportunity potentially provides investigators with both an image for suspect identification and chemical information to be used as additional intelligence. The latter becomes particularly important when the fingermark is distorted or smudged or when the suspect is not a previously convicted offender and therefore their fingerprints are not present in the National Fingerprint Database. One of the desirable pieces of intelligence would be the sex of the suspect from the chemical composition of a fingermark. In this study we show that the direct detection of peptides and proteins from fingermarks by MALDI MS Profiling (MALDI MSP), along with the multivariate modeling of the spectra, enables the determination of sex with 85% accuracy. The chemical analysis of the fingermark composition is expected to additionally provide information on traits such as nutritional habits, drug use or hormonal status.

Predicting in vivo starch digestibility coefficients in newly weaned piglets from in vitro assessment of diets using multivariate analysis.

The study was based on correlating a dataset of in vivo mean starch digestibility coefficients obtained in the immediate post-weaning phase of piglets with a range of dietary in vitro variables. The paper presents a model that predicts (R2 0.71) in vivo average starch digestibility coefficients in the 0.5 small-intestinal region of newly weaned piglets fed cereal-based diets using seven in vitro variables describing starch properties that are fundamentally associated with the quality of feed materials, i.e. hydration, structure and amylolytic digestion. The variables were: Rapid Visco Analyser (RVA; measures the viscosity of materials when sheared under defined hydration and temperature regimens); RVA end viscosity; RVA (gelatinisation) peak viscosity; DeltaH (gelatinisation enthalpy that provides an estimate of helical order or degree of crystallinity in starch); water solubility index (WSI; that denotes the amount of soluble polysaccharides released from starch granules to the aqueous phase); grain endogenous amylase (concentration of endogenous alpha-amylase in cereals, assessed by pasting cereal flours in 25 g of AgNO3, an amylase inhibitor v. water using RVA).

Effect of preparation conditions on release of selected volatiles in tea headspace.

The release of volatile compounds from infused tea was monitored using on-line atmospheric pressure chemical ionization (APCI) mass spectrometry. Assignment of the APCI ions to particular compounds was achieved using gas chromatography of tea headspace with dual electron ionization and APCI-MS detectors. Six ions in the APCI spectrum could be assigned to individual compounds, five ions were associated with isobaric compounds (e.g., 2- and 3-methylbutanal and pentanal) or stereoisomers (e.g., heptenals or heptadienals), and a further four ions monitored were identified compounds but with some unknown impurities. Reproducibility of infusion preparation and the analytical system was good with percentage variation values generally below 5%. The analysis was used to study the effect of infusion and holding temperatures on the volatile profile of tea headspace samples, and this was found to be compound-dependent. Both the extraction of volatiles from leaf tea and the release of volatiles into the headspace play a role in creating the aroma profile that the consumer experiences.

Oral processing assessed by M-mode ultrasound imaging varies with food attribute.

Ultrasonic imaging was used to quantify oral movements made during the oral processing of foods while subjects assessed the intensity of the sensory attributes, thick, creamy, sweet and bitter. A series of four stimuli were prepared with high and low viscosities and high and low sweetness. Over five sessions, subjects (N=8) were asked to consume 5 ml spoonfuls of each of the stimuli while holding an ultrasound probe beneath their chin so as to produce a mid-line sagital image of the floor of the mouth and tongue. In the first session, subjects were asked to swallow the sample. In subsequent sessions, subjects were asked to rate one of the attributes, thickness, sweetness, creaminess or bitterness, in random order. The resulting video recordings were subjected to an image-processing algorithm to quantify the amount of intra-oral manipulation performed. The results demonstrated that oral movements varied with attribute, especially in the period during which the bulk of the food is typically processed and the following swallowing phase. The food's sweetness affected oral movements especially during the bulk phase, whereas the food's viscosity primarily affected movements during the following swallowing and clearance phases.

Expression profiling of pectinolytic genes from Aspergillus niger.

The expression of 26 pectinolytic genes from Aspergillus niger was studied in a wild type strain and a CreA derepressed strain, under 16 different growth conditions, to obtain an expression profile for each gene. These expression profiles were then submitted to cluster analysis to identify subsets of genes with similar expression profiles. With the exception of the feruloyl esterase encoding genes, all genes were expressed in the presence of D-galacturonic acid, polygalacturonate, and/or sugar beet pectin. Despite this general observation five distinct groups of genes were identified. The major group consisted of 12 genes of which the corresponding enzymes act on the pectin backbone and for which the expression, in general, is higher after 8 and 24 h of incubation, than after 2 or 4 h. Two other groups of genes encoding pectin main chain acting enzymes were detected. Two additional groups contained genes encoding L-arabinose and D-galactose releasing enzymes, and ferulic acid releasing enzymes, respectively. The genes encoding beta-galactosidase and the L-arabinose releasing enzymes were not only expressed in the presence of D-galacturonic acid, but also in the presence of L-arabinose, suggesting that they are under the control of two regulatory systems. Similarly, the rhamnogalacturonan acetylesterase encoding gene was not only expressed in the presence of D-galacturonic acid, polygalacturonate and sugar beet pectin, but also in the presence of L-rhamnose. The data presented provides indications for a general pectinolytic regulatory system responding to D-galacturonic acid or a metabolite derived from it. In addition, subsets of pectinolytic genes are expressed in response to the presence of L-arabinose, L-rhamnose or ferulic acid.

Nutrimetabolomics: development of a bio-identification toolbox to determine the bioactive compounds in grape juice.

BACKGROUND: Grape juice and related products have previously been associated with many health benefits, such as protection against cardiovascular disease. Current consensus is that the polyphenols are the likely bioactive species in these products. RESULTS: Extracts of commercially available grape juices exhibited biological antioxidant activities ranging from 19.30 to 3099.51 µM trolox equivalents, as determined by cell-based assay in which J774 macrophages were stimulated with lipopolysaccaride at a concentration of 100 µg/ml for 1 h. Partial least-squares regression was then used to determine covariance between the antioxidant activity and 400 MHz (1)H NMR spectral profiles using models with R(2)X and R(2)Y values of 0.64 and 0.95, respectively, using three latent variables: the Q(2)(cum) was 0.63. Hydroxycinnamic acids and their derivatives were identified as being the most positively correlated with the antioxidant activity. CONCLUSION: The work presented here describes a strategy for the bioinformatic linkage of plant metabolomic data with in vitro biological activity as an initial step towards determining structure-activity relationships.

Identification and monitoring of intermediates and products in the acrylamide pathway using online analysis.

Acrylamide formation under controlled processing conditions was studied in a starch matrix by analyzing volatile compounds in the gas phase using online mass spectrometry. Compounds were identified using mass spectral analysis, authentic standards, and the labeling patterns from isotopically labeled asparagine and sugars. Acrylamide, 3-aminopropanamide, methylpyrazine, 3-oxopropanamide, and aminopropan-2-one were assigned to the ions at m/ z 72, 89, 95, 88, and 74, respectively. Ion m/ z 60 was proposed as the transamination product of glyoxal, but labeling experiments did not support this assignment. Temporal formation of acrylamide and related compounds was studied in 51 samples containing asparagine and selected sugars or carbonyls. Data from the experiments were analyzed to investigate correlations between the amounts of acrylamide, intermediates, and pyrazines formed. A strong correlation between 3-aminopropanamide and acrylamide was found in all samples, whereas other correlations were reactant specific. Preliminary multiway analysis of the data identified temporal similarities in the ion profiles and showed that dynamic monitoring can follow the production and utilization of intermediates leading to acrylamide.

Measurement of ischaemia-reperfusion in patients with intermittent claudication using NMR-based metabonomics.

Intermittent claudication has proved to be a good in vivo model for ischaemia-reperfusion. For assessment of ischaemia-reperfusion damage, the known biochemical markers all have disadvantages with respect to sensitivity and interference with other physiological events. In this work, we studied the metabolic effects of ischaemia-reperfusion in patients with intermittent claudication, and the effects of vitamin C and E intervention, using both traditional biochemical measurements and 1H-NMR-based metabonomics on urine and plasma. The 1H-NMR spectra were subjected to multivariate modelling using principal components discriminant analysis, and the observed clusters were validated using joint deployment of univariate analysis of variance and Tukey-Kramer honestly significant difference (HSD) testing. The study involved 14 patients with intermittent claudication and three healthy volunteers, who were monitored during a walking test, before and after a vitamin C/E intervention, and after a washout period. The effect of exercise was only observable for a limited number of biochemical markers, whereas 1H NMR revealed an effect in line with anaerobic ATP production via glycolysis in exercising (ischaemic) muscle of the claudicants. Thus, the beneficial effect of vitamins C and E in claudicants was more pronounced when observed by metabonomics than by traditional biochemical markers. The main effect was more rapid recovery from exercise to resting state metabolism. Furthermore, after intervention, claudicants tended to have lower concentrations of lactate and glucose and several other citric acid cycle metabolites, whereas acetoacetate was increased. The observed metabolic changes in the plasma suggest that intake of vitamin C/E leads to increased muscle oxidative metabolism.