Determination of the degradation kinetics of anthocyanins in a model juice system using isothermal and non-isothermal methods

The effect of temperature on the degradation of blackcurrant anthocyanins in a model juice system was determined over a temperature range of 4–140 °C. The thermal degradation of anthocyanins followed pseudo first-order kinetics. From 4–100 °C an isothermal method was used to determine the kinetic parameters. In order to mimic the temperature profile in retort systems, a non-isothermal method was applied to determine the kinetic parameters in the model juice over the temperature range 110–140 °C. The results from both isothermal and non-isothermal methods fit well together, indicating that the non-isothermal procedure is a reliable mathematical method to determine the kinetics of anthocyanin degradation. The reaction rate constant (k) increased from 0.16 (±0.01) × 10−3 to 9.954 (±0.004) h−1 at 4 and 140 °C, respectively. The temperature dependence of the rate of anthocyanin degradation was modelled by an extension of the Arrhenius equation, which showed a linear increase in the activation energy with temperature.

Modeling migratory grazing of zooplankton on toxic and non-toxic phytoplankton

Migratory grazing of zooplankton between non-toxic phytoplankton (NTP) and toxic phytoplankton (TPP) is a realistic phenomena unexplored so far. The present article is a first step in this direction. A mathematical model of NTP–TPP-zooplankton with constant and variable zooplankton migration is proposed and analyzed. The asymptotic dynamics of the model system around the biologically feasible equilibria is explored through local stability analysis. The dynamics of the proposed system is explored and displayed for different combination of migratory parameters and toxin inhibition parameters. Our analysis suggests that the migratory grazing of zooplankton has a significant role in determining the dynamic stability and oscillation of phytoplankton zooplankton systems.

Consistent approximate models of the global atmosphere: shallow, deep, hydrostatic, quasi-hydrostatic and non-hydrostatic

We study global atmosphere models that are at least as accurate as the hydrostatic primitive equations (HPEs), reviewing known results and reporting some new ones. The HPEs make spherical geopotential and shallow atmosphere approximations in addition to the hydrostatic approximation. As is well known, a consistent application of the shallow atmosphere approximation requires omission of those Coriolis terms that vary as the cosine of latitude and of certain other terms in the components of the momentum equation. An approximate model is here regarded as consistent if it formally preserves conservation principles for axial angular momentum, energy and potential vorticity, and (following R. Müller) if its momentum component equations have Lagrange's form. Within these criteria, four consistent approximate global models, including the HPEs themselves, are identified in a height-coordinate framework. The four models, each of which includes the spherical geopotential approximation, correspond to whether the shallow atmosphere and hydrostatic (or quasi-hydrostatic) approximations are individually made or not made. Restrictions on representing the spatial variation of apparent gravity occur. Solution methods and the situation in a pressure-coordinate framework are discussed. © Crown copyright 2005.

In vitro degradability of mature and immature leaves of tropical forage legumes differing in condensed tannin and non-starch polysaccharide content and composition

A study was designed to examine the relationships between protein, condensed tannin and cell wall carbohydrate content and composition and the nutritional quality of seven tropical legumes (Desmodium ovalifolium, Flemingia macrophylla, Leucaena leucocephala, L pallida, L macrophylla, Calliandra calothyrsus and Clitotia fairchildiana). Among the legume species studied, D ovalifolium showed the lowest concentration of nitrogen, while L leucocephala showed the highest. Fibre (NDF) content was lowest in C calothyrsus, L Leucocephala and L pallida and highest in L macrophylla, which had no measurable condensed tannins. The highest tannin concentration was found in C calothyrsus. Total non-structural polysaccharides (NSP) varied among legumes species (lowest in C calothyrsus and highest in D ovalifolium), and glucose and uronic acids were the most abundant carbohydrate constituents in all legumes. Total NSP losses were lowest in F macrophylla and highest in L leucocephala and L pallida. Gas accumulation and acetate and propionate levels were 50% less with F macrophylla and D ovalifolium as compared with L leucocephala. The highest levels of branched-chain fatty acids were observed with non-tanniniferous legumes, and negative concentrations were observed with some of the legumes with high tannin content (D ovalifolium and F macrophylla). Linear regression analysis showed that the presence of condensed tannins was more related to a reduction of the initial rate of gas production (0-48 h) than to the final amount of gas produced or the extent (144h) of dry matter degradation, which could be due to differences in tannin chemistry. Consequently, more attention should be given in the future to elucidating the impact of tannin structure on the nutritional quality of tropical forage legumes. (C) 2003 Society of Chemical Industry.

Follicle-stimulating hormone isoforms and plasma concentrations of estradiol and inhibin A in dairy cows with ovulatory and non-ovulatory follicles during the first postpartum follicle wave

Following parturition, all cows display a wave of ovarian follicular growth, but a large proportion fail to generate a preovulatory rise in estradiol, and hence fail to ovulate. Follicle-stimulating hormone (FSH) exists as multiple isoforms in the circulation depending on the type and extent of glycosylation, and this has pronounced effects on its biological properties. This study examined differences in plasma FSH, estradiol, and inhibin A concentrations, and the distribution of FSH isoforms in cows with ovulatory or atretic dominant follicles during the first postpartum follicle wave. Plasma FSH isoform distribution was examined in both groups during the period of final development of the dominant follicle by liquid phase isoelectric focusing. Cows with an ovulatory follicle had higher circulating estradiol and inhibin A concentrations, and lower plasma FSH concentrations. The distribution of FSH isoforms displayed a marked shift toward the less acidic isoforms in cows with ovulatory follicles. A higher proportion of the FSH isoforms had a pl>5.0 in cows with ovulatory follicles compared to those with atretic follicles. In addition, cows with ovulatory follicles had greater dry matter intake, superior energy balance, elevated circulating concentrations of insulin and insulin-like growth factor-I, and lower plasma nonesterified fatty acids. The shift in FSH isoforms toward a greater abundance of the less acidic isoforms appears to be a key component in determining the capability for producing a preovulatory rise in estradiol, and this shift in FSH isoforms was associated with more favorable bioenergetic and metabolic status. (C) 2008 Elsevier Inc. All rights reserved.

Dietary glycated protein modulates the colonic microbiota towards a more detrimental composition in ulcerative colitis patients and non-ulcerative colitis subjects

AIM: To investigate the effect of native, heated and glycated bovine serum albumin (BSA) on the ulcerative colitis (UC) and non-UC colonic microbiota in vitro. METHODS AND RESULTS: Continuous flow culture (CFC) models of the human colonic microbiota inoculated with faeces from UC and non-UC volunteers were maintained on BSA as growth substrate. Changes in bacterial populations and short-chain fatty acids were determined. UC and non-UC microbiota differed significantly in microbial populations, with elevated numbers of sulfate-reducing bacteria (SRB) and clostridia in the microbiota from UC patients. Compared with native BSA, glycated BSA modulated the gut microbiota of UC patients in vitro towards a more detrimental community structure with significant increases in putatively harmful bacteria (clostridia, bacteroides and SRB; P < 0.009) and decreases in dominant and putatively beneficial bacterial groups (eubacteria and bifidobacteria; P < 0.0004). The levels of beneficial short-chain fatty acids were significantly decreased by heated or glycated BSA, but were increased significantly by native BSA. CONCLUSION: The UC colonic microbiota maintained in CFC was significantly modified by glycated BSA. SIGNIFICANCE AND IMPACT OF THE STUDY: Results suggest that dietary glycated protein may impact upon the composition and activity of the colonic microbiota, an important environmental variable in UC.

Post dispersal weed seed predation by avian and non-avian predators

Seed predation by avian and non-avian predators was quantified in the boundaries and cropped areas of cereal fields by presenting known quantities of seed with and without exclusion cages. Predator encounter-rates with the dishes exceeded 99%. Birds removed on average 6.7% seed from the dishes during the seven-day trials compared to 51% by non-avian predators. A comparison was made of the causal factors responsible for predation of Avena fatua, Chenopodium album and Cirsium arvense seeds. A. fatua seeds were preyed most heavily by both avian and non-avian predators. Seed removal by birds was greater in the cropped area than in the field boundary, non-avian predators being generally more active in the field boundary. Seed predation by birds was greater in spring than in any other season, whilst losses to other animals were greater during autumn and winter. Although, birds were not the main seed predators in cereal fields, they may contribute to weed seed depletion, of relevance to reduced-input farming systems where herbicides use is restricted.

Design of supramolecular beta-sheet forming beta-turns containing aromatic rings and non-coded alpha-aminoisobutyric acid and the formation of flat fibrillar structures through self-assembly

Single crystal X-ray diffraction studies show that the three designed tripeptides Boc-Leu-Aib-m-NA-NO2 (I), Boc-Phe-Aib-m-NA-NO2 (II) and Boc-Pro-Aib-m-ABA-OMe (III) (Aib, -aminoisobutyric acid; m-NA, m-nitroaniline; m-ABA, m-aminobenzoic acid; Boc, t-butyloxycarbonyl) containing aromatic rings in the backbones adopt -turn structures that are self-assembled through intermolecular hydrogen bonds and van der Waals interactions to create layers of -sheets. Solvent-dependent NMR titration and CD studies show that the -turn structures of the peptides also exist in the solution phase. The field emission scanning electron microscopic and transmission electron microscopic images of the peptides in the solid state reveal fibrillar structures of flat morphology that are formed through -sheet mediated self-assembly of the preorganised -turn building blocks.

Comparative performance of UK PFI and non-PFI hospitals

Since the first PFI hospital was established in 1994, many debates centred on the value for money and risk transfer in PFIs. Little concern is shown with PFI hospitals’ performance in delivering healthcare. Exploratory research was carried out to compare PFI with non‐PFI hospital performance. Five performance indicators were analysed to compare differences between PFI and non‐PFI hospitals, namely the length of waiting, the length of stay, MRSA infection rate, C difficile infection rate and patient experience. Data was collected from various government bodies. The results show that only some indexes measuring patient experience emerge statistically significant. This leads to a conclusion that PFI hospitals may not perform better than non‐PFI hospitals but they are not worse than non‐PFI hospitals in the delivery of services. However, future research needs to pay attention to reliability and validity of data sets currently available to undertake comparison.