Effects of resistant starch type III polymorphs on human colon microbiota and short chain fatty acids in human gut models

This study probed the possible effects of type III resistant starch (RS) crystalline polymorphism on RS fermentability by human gut microbiota and the short chain fatty acids production in vitro. Human fecal pH-controlled batch cultures showed RS induces an ecological shift in the colonic microbiota with polymorph B inducing Bifidobacterium spp. and polymorph A inducing Atopobium spp. Interestingly, polymorph B also induced higher butyrate production to levels of 0.79 mM. In addition, human gut simulation demonstrated that polymorph B promotes the growth of bifidobacteria in the proximal part of the colon and double their relative proportion in the microbiota in the distal colon. These findings suggest that RS polymorph B may promote large bowel health. While the findings are limited by study constraints, they do raise the possibility of using different thermal processing to delineate differences in the prebiotic capabilities of RS, especially its butryrogenicity in the human colon.

Kinetics of high pressure facilitated starch gelatinisation in Thai glutinous rice

The combined effect of pressure and temperature on the rate of gelatinisation of starch present in Thai glutinous rice was investigated. Pressure was found to initiate gelatinisation when its value exceeded 200 MPa at ambient temperature. On the other hand, complete gelatinisation was observed at 500 and 600 MPa at 70 degrees C, when the rice was soaked in water under these conditions for 120 min. A first-order kinetic model describing the rate of gelatinisation was developed to estimate the values of the rate constants as a function of pressure and temperature in the range: 0.1-600 MPa and 20-70 degrees C. The model, based on the well-known Arrhenius and Eyring equations, assumed the form [GRAPHICS] The constants k(0), E-a, and Delta V were found to take values: 31.19 s(-1), 37.89 kJ mol(-1) and -9.98 cm(3) mol(-1), respectively. It was further noted that the extent of gelatinisation occurring at any time, temperature and pressure, could be exclusively correlated with the grain moisture content. (c) 2006 Elsevier Ltd. All rights reserved.

Verification of cloud-fraction forecasts

Cloud radar and lidar can be used to evaluate the skill of numerical weather prediction models in forecasting the timing and placement of clouds, but care must be taken in choosing the appropriate metric of skill to use due to the non- Gaussian nature of cloud-fraction distributions. We compare the properties of a number of different verification measures and conclude that of existing measures the Log of Odds Ratio is the most suitable for cloud fraction. We also propose a new measure, the Symmetric Extreme Dependency Score, which has very attractive properties, being equitable (for large samples), difficult to hedge and independent of the frequency of occurrence of the quantity being verified. We then use data from five European ground-based sites and seven forecast models, processed using the ‘Cloudnet’ analysis system, to investigate the dependence of forecast skill on cloud fraction threshold (for binary skill scores), height, horizontal scale and (for the Met Office and German Weather Service models) forecast lead time. The models are found to be least skillful at predicting the timing and placement of boundary-layer clouds and most skilful at predicting mid-level clouds, although in the latter case they tend to underestimate mean cloud fraction when cloud is present. It is found that skill decreases approximately inverse-exponentially with forecast lead time, enabling a forecast ‘half-life’ to be estimated. When considering the skill of instantaneous model snapshots, we find typical values ranging between 2.5 and 4.5 days. Copyright c 2009 Royal Meteorological Society

Plasma ghrelin and oxytomodulin concentrations in lactating dairy cows receiving abomasal soybean oil, corn starch, and casein infusions

The effects of increased postruminal supply of casein, corn starch, and soybean oil on plasma concentrations of the gastrointestinal hormones ghrelin and oxyntomodulin (OXM) were investigated. Four mid-lactation Holstein cows were used in a 4×4 Latin square. Treatments were continuous abomasal infusions (23h/d) for 7 d of water, soybean oil (500g/d), corn starch (1100g/d), or casein (800g/d). Jugular vein plasma was obtained every 30min for 7h on days 1 and 7. Soybean oil and casein infusion decreased preprandial plasma ghrelin concentration by approximately 20% on both d (time-by-treatment P<0.10); however, dry matter intake (DMI) was depressed only after 7 d of oil infusion. Infusion of soybean oil, corn starch, or casein did not change the plasma OXM concentration (P>0.20). The present data indicate that plasma ghrelin concentration is depressed immediately before feeding by the postruminal infusion of soybean oil and casein, but it is not affected during the postprandial period. Plasma ghrelin concentration was not altered (P>0.20), pre- or postfeeding, by increased postruminal supply of corn starch. In addition, plasma OXM concentration did not respond (P>0.20) to postruminal nutrient infusion. In conclusion, a decrease in DMI when fat is infused could be partially explained by the decrease in prefeeding plasma ghrelin concentration, but a decrease in prefeeding plasma ghrelin concentration is not always associated with a decrease in DMI, as observed for the infusion of casein. Plasma OXM concentration was not affected by postruminal infusion of macronutrients.

Is silt the most influential soil grain size fraction?

The contribution of individual grain size fractions (2000–500, 500–250, 250–63, 63–2 and < 2 μm) to bulk soil surface area and reactivity is discussed with reference to mineralogical and oxalate and dithionite extractions data. The 63–2 μm fraction contributed up to 56% and 67% of bulk soil volume and BET surface area, respectively. Consideration of these observations and the mineralogy of this fraction suggest that the 63–2 μm fraction may be the most influential for the release of elements via mineral dissolution in the bulk soil.

In vitro bioaccessibility and gut biotransformation of polyphenols present in the water-insoluble cocoa fraction

Scope: Cocoa, especially the water-insoluble cocoa fraction (WICF), is a rich source of polyphenols. In this study, sequential in vitro digestion of the WICF with gastrointestinal enzymes as well as its bacterial fermentation in a human colonic model system were carried out to investigate bioaccessibility and biotransformation of WICF polyphenols, respectively. Methods and results: The yield of each enzymatic digestion step and the total antioxidant capacity (TAC) were measured and solubilized phenols were characterized by MS/MS. Fermentation of WICF and the effect on the gut microbiota, SCFA production and metabolism of polyphenols was analyzed. In vitro digestion solubilized 38.6% of WICF with pronase and Viscozyme L treatments releasing 51% of the total phenols from the insoluble material. This release of phenols does not determine a reduction in the total antioxidant capacity of the digestion-resistant material. In the colonic model WICF significantly increased of bifidobacteria and lactobacilli as well as butyrate production. Flavanols were converted into phenolic acids by the microbiota following a concentration gradient resulting in high concentrations of 3-hydroxyphenylpropionic acid (3-HPP) in the last gut compartment. Conclusion: Data showed that WICF may exert antioxidant action through the gastrointestinal tract despite its polyphenols being still bound to macromolecules and having prebiotic activity.

Variability of starch-based thickened drinks for patients with dysphagia in the hospital setting

Starch-based thickening agents may be prescribed for patients with dysphagia. Thickened fluids alter variables of the swallow reflex, allowing more time for bolus manipulation without compromising airway closure. This investigation explored the variation in viscosity and physical characteristics of thickened drinks prepared in different media under laboratory conditions and compared the results with those of thickened drinks presented to dysphagic patients in one hospital. The rheological characteristics were tested on a simple plastometer and a Bohlin CVOR rheometer (Malvern Instruments, Worcestershire, UK). Samples prepared to “syrup” consistency both in the laboratory and in the hospitalwere significantly different from each other (P < 0.0001). This was also the case for samples prepared to “custard” consistency. Differences existed not only in viscosity, but drinks prepared in different media produced different rheological matrices. This signifies different viscoelastic behaviors that may effect manipulation in the mouth. From this study, preparation of thickened drinks using starch-based instant thickening powders appears to be a highly variable practice.

Divergent evolutionary pattern of starch biosynthetic pathway genes in grasses and dicots

Starch is the most widespread and abundant storage carbohydrate in crops and its production is critical to both crop yield and quality. As regards the starch content in the seeds of crop plants, there are distinct difference between grasses (Poaceae) and dicots. However, few studies have described the evolutionary pattern of genes in the starch biosynthetic pathway in these two groups of plants. In this study, therefore, an attempt was made to compare the evolutionary rate, gene duplication and selective pattern of the key genes involved in this pathway between the two groups, using five grasses and five dicots as materials. The results showed (i) distinct differences in patterns of gene duplication and loss between grasses and dicots; duplication in grasses mainly occurred prior to the divergence of grasses, whereas duplication mostly occurred in individual species within the dicots; there is less gene loss in grasses than in dicots; (ii) a considerably higher evolutionary rate in grasses than in dicots in most gene families analyzed; (iii) evidence of a different selective pattern between grasses and dicots; positive selection may have occurred asymmetrically in grasses in some gene families, e.g. AGPase small subunit. Therefore, we deduced that gene duplication contributes to, and a higher evolutionary rate is associated with, the higher starch content in grasses. In addition, two novel aspects of the evolution of the starch biosynthetic pathway were observed.

Intake fraction of nonreactive motor vehicle exhaust in HongKong

The intake fraction (iF) of nonreactive constituents of exhaust from mobile vehicles in the urban area of HongKong is investigated using available monitoring data for carbon monoxide (CO) as a tracer of opportunity. Correcting for regional transport of carbon monoxide into HongKong, the annual-average iF for nonreactive motor vehicle emissions within the city is estimated to be around 270 per million. This estimated iF is much higher than values previously reported for vehicle emissions in US urban areas, Helsinki and Beijing, and somewhat lower than those reported for a densely populated street canyon in downtown Manhattan, New York City, or for emissions into indoor environments. The reported differences in intakefractions in various cities mainly result from the differences in local population densities. Our analysis highlights the importance of accounting for the influence of upwind transport of pollutants when using ambient data to estimate iF for an urban area. For vehicleexhaust in HongKong, it is found that the in/near vehicle microenvironment contributes similarly to the indoor home environment when accounting for the overall iF for children and adults. Keywords Intakefraction; Vehicle emission; Regional pollutant transport; Carbon monoxide; Exposure

CO intake fraction and city ventilation rate in Hong Kong

Given the background of serious urban pollution in Hong Kong, the intake fraction (iF) of carbon monoxide due to mobile vehicles in urban area of Hong Kong is investigated and estimated to be 600 per million, much higher than those in US urban areas, Helsinki and even Beijing, indicating the high exposure level to urban pollutants in Hong Kong. The dependence of iF to the metrological factors is also discussed. Easterly and northerly winds contribute most to the total iF value. A new method of predicting ventilation rate for a city based on iF concept is proposed. City ventilation rates for different cities are calculated and compared. It is found that Hong Kong has to face the fact that it has the lowest ventilation rate and ACH.

Alternating sums of binomial coefficients with unit fraction arithmetic sequence coefficients

Expressions for finite sums involving the binomial coefficients with unit fraction coefficients whose denominators form an arithmetic sequence are determined.

Diversity of cultivars and other plant resources used at habitation sites in the Llanos de Mojos, Beni, Bolivia: Evidence from macrobotanical remains, starch grains, and phytoliths

Although sparsely populated today, the Llanos de Mojos, Bolivia, sustained large sedentary societies in the Late Holocene (ca. 500 to 1400 AD). In order to gain insight into the subsistence of these people, we undertook macrobotanical and phytolith analyses of sediment samples, and starch grain and phytolith analyses of artifact residues, from four large habitation sites within this region. Macrobotanical remains show the presence of maize (Zea mays), squash (Cucurbita sp.), peanut (Arachis hypogaea), cotton (Gossypium sp.), and palm fruits (Arecaceae). Microbotanical results confirm the widespread use of maize at all sites, along with manioc (Manihot esculenta), squash, and yam (Dioscorea sp.). These integrated results present the first comprehensive archaeobotanical evidence of the diversity of plants cultivated, processed, and consumed, by the pre-Hispanic inhabitants of the Amazonian lowlands of Bolivia.

Variability of marine aerosol fine-mode fraction and estimates of anthropogenic aerosol component over cloud-free oceans from the Moderate Resolution Imaging Spectroradiometer (MODIS)

In this study, we examine seasonal and geographical variability of marine aerosol fine-mode fraction ( fm) and its impacts on deriving the anthropogenic component of aerosol optical depth (ta) and direct radiative forcing from multispectral satellite measurements. A proxy of fm, empirically derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) Collection 5 data, shows large seasonal and geographical variations that are consistent with the Goddard Chemistry Aerosol Radiation Transport (GOCART) and Global Modeling Initiative (GMI) model simulations. The so-derived seasonally and spatially varying fm is then implemented into a method of estimating ta and direct radiative forcing from the MODIS measurements. It is found that the use of a constant value for fm as in previous studies would have overestimated ta by about 20% over global ocean, with the overestimation up to �45% in some regions and seasons. The 7-year (2001–2007) global ocean average ta is 0.035, with yearly average ranging from 0.031 to 0.039. Future improvement in measurements is needed to better separate anthropogenic aerosol from natural ones and to narrow down the wide range of aerosol direct radiative forcing.

Grouping of 24 apple cultivars on the basis of starch degradation rate and their fruit pattern

The ripening processes of 24 apple cultivars were examined in the United Kingdom National Fruit Collection in 2010. Basically the starch content, and additionally ground colour, water-soluble solids content and flesh firmness were studied during ripening. The degradation of the starch content was evaluated using a 0–10 scale. A starch degradation value of 50% was taken to be the optimum harvest date, with harvest beginning at a value of 40% and finishing at 60%. Depending on the cultivar, this represented a harvest window of 9 to 21 days. Later ripening cultivars matured more slowly, leading to a longer harvesting period, with the exception of cv. Feuillemorte. Pronounced differences were observed among the cultivars on the basis of the starch degradation pattern, allowing them to be divided into four groups. Separate charts were elaborated for each group that are recommended for use in practice.