Characterizing blood metabolomics profiles associated with self-reported food intakes in female twins

Using dietary biomarkers in nutritional epidemiological studies may better capture exposure and improve the level at which diet-disease associations can be established and explored. Here, we aimed to identify and evaluate reproducibility of novel biomarkers of reported habitual food intake using targeted and non-targeted metabolomic blood profiling in a large twin cohort. Reported intakes of 71 food groups, determined by FFQ, were assessed against 601 fasting blood metabolites in over 3500 adult female twins from the TwinsUK cohort. For each metabolite, linear regression analysis was undertaken in the discovery group (excluding MZ twin pairs discordant [≥1 SD apart] for food group intake) with each food group as a predictor adjusting for age, batch effects, BMI, family relatedness and multiple testing (1.17x10-6 = 0.05/[71 food groups x 601 detected metabolites]). Significant results were then replicated (non-targeted: P<0.05; targeted: same direction) in the MZ discordant twin group and results from both analyses meta-analyzed. We identified and replicated 180 significant associations with 39 food groups (P<1.17x10-6), overall consisting of 106 different metabolites (74 known and 32 unknown), including 73 novel associations. In particular we identified trans-4-hydroxyproline as a potential marker of red meat intake (0.075[0.009]; P = 1.08x10-17), ergothioneine as a marker of mushroom consumption (0.181[0.019]; P = 5.93x10-22), and three potential markers of fruit consumption (top association: apple and pears): including metabolites derived from gut bacterial transformation of phenolic compounds, 3-phenylpropionate (0.024[0.004]; P = 1.24x10-8) and indolepropionate (0.026[0.004]; P = 2.39x10-9), and threitol (0.033[0.003]; P = 1.69x10-21). With the largest nutritional metabolomics dataset to date, we have identified 73 novel candidate biomarkers of food intake for potential use in nutritional epidemiological studies. We compiled our findings into the DietMetab database (http://www.twinsuk.ac.uk/dietmetab-data/), an online tool to investigate our top associations

Triplex formation at physiological pH by oligonucleotides incorporating 5-Me-dC-(N<SUP>4</SUP>-spermine)

Oligonucleotide (ODN) directed tripler formation has therapeutic importance and depends on Hoogsteen hydrogen bonds between a duplex DNA and a third strand. While T&#8727;A:T triplets are formed at neutral pH, C+&#8727;G:C are favoured at acidic pH. Herein it is shown that 18-mer ODN containing spermine conjugated to 5-Me-dC at N4 (1-5), form triplexes with complementary 24-mer duplex 8:9 at neutral pH (7.3, 100 mM NaCl). Under such conditions, control ODN's carrying dC (6) or 5-Me-dC (7) did not show any triple helix formation. Remarkably, the triplexes from spermine-conjugates (1-5) have foremost stability at neutral pH (7.1), unlike the behavior of normal ODN's where optimal stability is at acidic pH (5.5). These results have importance in designing oligonucleotides for antigene applications

Exploring DNA minor groove interactions through a probe conjugate in major groove: fluorescence studies on netrosin complexation with dU-5-aminodansyl-DNA

The binding of netropsin to 5-Aminodansyl-dU-DNA (2-5) in minor groove is shown to correlate with fluorescence changes of dansyl fluorophore located in major groove. This enables a study of a minor groove binding event through crosstalk with conjugated probe in major groove. The dielectric constant of major groove estimated from fluorescence properties of (2-6) is about 55D in contrast to the literature reported minor groove dielectric constant of 20D in the poly[d(AT)]-poly[d(AT)] duplex

Highly efficient one-pot amination of carboxylate-substituted nitrogen-containing heteroaryl chlorides via Staudinger reaction

An efficient one-pot method for the synthesis of tert-butyl 6-aminonicotinate (5) is described. The key transformation involves displacement of the chloro group in tert-butyl 6-chloronicotinate (2) with azide followed by a Staudinger reaction. The scope of this methodology is further extended for the synthesis of a series of carboxylate-substituted heteroaryl amines. In particular, we synthesized tert-butyl carboxylate-substituted amino-pyridine, -pyridazine, and -pyrazine. In addition to one-pot conversion, short reaction time, simplicity of operation, ease of purification, and good yields are the key advantages of this methodology