The acute effects of a pulse-containing meal on glycaemic responses and measures of satiety and satiation within and at a later meal.

Pulses are low glycaemic foods; however, their effect on satiation is unknown. The objective was to determine the effects of an ad libitum pulse meal on food intake (FI), appetite and blood glucose (BG) before and after a test meal (4 h later) and on FI at the test meal. Males (n 24, 22·8 kg/m2) received one of four treatments or control. The pulse treatments contained pasta and tomato sauce and 44 % of energy from: (1) chickpeas, (2) lentils, (3) navy beans or (4) yellow peas. The control was pasta and tomato sauce (pasta and sauce). FI (satiation) was measured at the treatment meal (0-20 min) and at an ad libitum pizza meal 4 h later. BG and appetite were measured from 0 to 340 min. At the treatment meal, lentils led to lower FI compared to chickpeas and pasta and sauce, whereas navy beans led to lower FI compared to chickpeas. Also, lentils led to lower cumulative FI compared to pasta and sauce. All pulses led to lower BG peak and cumulative area under the curve (AUC; 0-340 min); however, only chickpeas, lentils and navy beans reduced pre-pizza meal BG AUC (0-260 min) relative to pasta and sauce. Chickpeas led to lower post-pizza meal BG AUC (260-340 min) compared to navy beans and yellow peas. Consumption of pulses in a high-glycaemic meal contributes to earlier satiation, lower BG following the meal and after a later meal, but these effects are specific to pulse type and cannot be explained by their glycaemic properties alone.

A comparison of analytical techniques for evaluating food waste degradation by anaerobic digestion.

Organic matter contained in food waste was degraded by anaerobic digestion under mesophilic and thermophilic conditions at two hydraulic retention times. Evolution of the digestion process was followed by thermogravimetry analysis, fluorescence spectroscopy and (1)H nuclear magnetic resonance. All analytical methods suggested that longer retention times might be required for food waste stabilization under mesophilic conditions as compared to thermophilic stabilization. All the analytical methods showed that the stabilization process consisted of two steps, where complex organic molecules were formed during initial stabilization and then digested providing sufficient hydraulic retention time. Longer hydraulic retention times were required for food waste stabilization under mesophilic conditions. Overall, thermal and (1)H NMR analyses of the digestate samples might be recommended if more detailed analysis is required, while fluorescence measurements can be used as a fast screening technique, which provides qualitative assessment of the stabilization process.

Biochemical characterization of the 2-ketoacid reductases encoded by ycdW and yiaE genes in Escherichia coli.

Glyoxylate is an important intermediate of the central microbial metabolism formed from acetate, allantoin or glycolate. Depending on the physiological conditions, glyoxylate is incorporated into the central metabolism by the combined actions of the activity of malate synthase and the D-glycerate pathway, or alternatively it can be reduced to glycolate by constitutive glyoxylate reductase activity. At present no information is available on this latter enzyme in Escherichia coli, although similar enzymes, classified as 2-hydroxyacid dehydrogenases, have been characterized in other organisms. A BLAST search using as the query sequence the hydroxypyruvate/glyoxylate reductase from Cucumis sativus identified as an orthologue the yiaE gene of E. coli encoding a ketoaldonate reductase. Use of this sequence in a subsequent BLAST search yielded the ycdW gene as a good candidate to encode glyoxylate reductase in this bacterium. Cloning and overexpression of the ycdW gene showed that its product displayed a high NADPH-linked glyoxylate reductase activity, and also catalysed the reduction of hydroxypyruvate with a lower efficiency. Disruption of the ycdW gene by a chloramphenicol acetyltransferase ('CAT') cassette did not totally abolish the glyoxylate reductase activity, indicating that another enzyme accomplished this function. The similarity with YiaE led us to test whether this protein was responsible for the remaining glyoxylate reductase activity. Purification of YcdW and YiaE proteins permitted their kinetic characterization and comparison. Analysis of the catalytic power (k(cat)/K(m)) disclosed a higher ratio of YcdW for glyoxylate and of YiaE for hydroxypyruvate.

Separation of urinary estrogens by micellar electrokinetic chromatography.

Urinary estrogen levels are important for monitoring the normal pregnancy process as well as for the diagnosis of reproductive diseases. 17 beta-Estradiol and estrone are maintained at very low concentrations in urine and, therefore, are difficult to determine using standard chromatography with UV detection. In the present study, we describe a potential method for the determination of urinary estrogens (estrone, estradiol and estriol) using a solid-phase extraction and rapid capillary electrophoretic (CE) separations. Micellar electrokinetic chromatographic (MEKC) analysis was optimized by evaluating the number of surfactants in a 5 mM borate-5 mM phosphate separation buffer, of which sodium cholate (75-90 mM) was found to be optimal. Changing the hydrophobic character of the separation buffer with organic additives had a significant effect on the resolution of the three estrogens and an internal standard (d-equilenin). The addition of an organic additive (20% acetonitrile) was found to be necessary for the resolution of all components of the mixture. Substitution with 20% methanol provided a similar separation with better resolution but at the cost of increased analysis time. Analysis of two extracted urine samples from 18-weeks and 21-weeks pregnant women showed that, with the present technology, CE can provide adequate resolution and superior speed, but the sensitivity limits attainable with the existing technology may limit its utility to the measurement of estriol and estrone.