Simple saponification method for the quantitative determination of carotenoids in green vegetables     

Larsen E  Christensen LP 《Journal of agricultural and food chemistry》2005,53(17):6598-6602

A simple, reliable, and gentle saponification method for the quantitative determination of carotenoids in green vegetables was developed. The method involves an extraction procedure with acetone and the selective removal of the chlorophylls and esterified fatty acids from the organic phase using a strongly basic resin (Ambersep 900 OH). Extracts from common green vegetables (beans, broccoli, green bell pepper, chive, lettuce, parsley, peas, and spinach) were analyzed by high-performance liquid chromatography (HPLC) for their content of major carotenoids before and after action of Ambersep 900 OH. The mean recovery percentages for most carotenoids [(all-E)-violaxanthin, (all-E)-lutein epoxide, (all-E)-lutein, neolutein A, and (all-E)-beta-carotene] after saponification of the vegetable extracts with Ambersep 900 OH were close to 100% (99-104%), while the mean recovery percentages of (9'Z)-neoxanthin increased to 119% and that of (all-E)-neoxanthin and neolutein B decreased to 90% and 72%, respectively.  相似文献   

Is the prevalence of dehydration among community-dwelling older adults really low? Informing current debate over the fluid recommendation for adults aged 70+years     

Stookey JD  Pieper CF  Cohen HJ 《Public health nutrition》2005,8(8):1275-1285

OBJECTIVE: The fluid recommendation for adults aged 70+ years has been criticised on the basis of a low prevalence of dehydration in community-dwelling older adults. This study explores whether the low prevalence might reflect limitations of individual dehydration indices. DESIGN: Cross-sectional data on plasma sodium, blood urea nitrogen (BUN), creatinine, glucose and potassium were used to classify 1,737 participants of the 1992 Established Populations for Epidemiologic Studies of the Elderly (EPESE) (70+ years) according to multiple dehydration indices. Associations between dehydration indices, health and functional status were evaluated. RESULTS: Depending on the indicator used, the prevalence of dehydration ranged from 0.5% for hypotonic hypovolaemia only (plasma tonicity < 285 mOsm l(-1) with orthostatic hypotension) to 60% with dehydration defined as either plasma sodium >or=145 mEq l(-1), BUN/creatinine ratio >or=20, tonicity >or=295 mOsm l(-1), or hypotonic hypovolaemia. Elevated tonicity and BUN/creatinine ratio were respectively associated with chronic disease and functional impairment. CONCLUSIONS: The true prevalence of dehydration among community-dwelling adults may be low or high, depending on the indicator(s) used to define dehydration. Before we can pinpoint a generalisable prevalence of dehydration for community-dwelling seniors and draw conclusions about fluid recommendations, validation studies of dehydration indices and longitudinal studies of dehydration, health and functional status are needed.  相似文献   

Air Pollution and Lichen Physiology. Physiological Responses of Different Lichens in a Transplant Experiment Following an SO2-Gradient     

Häffner  Eva  Lomský  Bohumir  Hynek  Vladimir  Hällgren  Jan Erik  Batič  Franc  Pfanz  Hardy 《Water, air, and soil pollution》2001,131(1-4):185-201

Four lichen species, Parmelia sulcata Taylor, Hypogymnia physodes (L.) Nyl., Cetraria islandica (L.)Ach., and Bryoria fuscescens (Gyelnik) Brodo andHawksworth were exposed during autumn and winter at differentsites of the Erzgebirge (Ore Mountains), the Fichtelgebirge andcontrol sites. All lichens tested became visibly damaged withtime. Thallus bleaching started from the edges and went on tothe centre of the thallus. Sites of facilitated gas exchangelike the soralia of P. sulcata and the pseudocyphelles ofC. islandica became preferentially bleached. The sulfateconcentration increased with exposure time reaching 200% ofunpolluted controls. In contrast to coniferous trees (e.g. Picea abies), further exposure lead to a reduction in the S-concentration in the lichens, as sulfate and otherintracellular metabolites were leached from the thalli due tomembrane damage. The changes in the K-concentration proved tobe an excellent measure for membrane leakiness; it wascorrelated with time of exposure and with SO₂ concentrations at the different sites. Photosynthetic capacityand respiration were also strongly affected. Depending on theSO₂-dose, the Bryoria species were unable tophotosynthesize as early as 4–8 weeks after exposure, whereasCetraria and Hypogymnia showed clear reduction intheir ability to photoreduce CO₂ within 8–10 weeks ofexposure in the field. Parmelia sulcata was found to bethe most tolerant species. After 3–4 months, photosynthesis wasreduced by only 30%. The bioindicative value of theseobservations is discussed.  相似文献   

Patterns of roost use by bats in a neotropical savanna: implications for conservation     

Luis F Aguirre  Luc Lens  Erik Matthysen 《Biological conservation》2003,111(3):435-443

Neotropic bats comprise a highly species-rich group and are considered important regulators of complex ecological processes. Resource partitioning of roosts and food is considered a key element in shaping bat communities. In this paper we examine the roosting patterns of 10 bat species belonging to a neotropical bat community in a Bolivian savanna. Roosts were more common in open woodlands than in forest islands and human settlements. In open woodlands, Tabebuia heptaphylla comprised the largest proportion of roosting trees, whereas in forest islands, Gallesia integrifolia was the most important roosting tree for phyllostomid bats. By comparing active roosts with control holes in Tabebuia heptaphylla, we found that roost site selection by Noctilio albiventris was mainly based on tree diameter and inner width of the cavities. The earlier results are discussed in view of resource partitioning within savanna bat communities and their practical conservation.  相似文献   

Acid-induced cold gelation of globular proteins: effects of protein aggregate characteristics and disulfide bonding on rheological properties   总被引：1，自引：0，他引：1  

Alting AC  Weijers M  de Hoog EH  van de Pijpekamp AM  Cohen Stuart MA  Hamer RJ  de Kruif CG  Visschers RW 《Journal of agricultural and food chemistry》2004,52(3):623-631

The process of cold gelation of ovalbumin and the properties of the resulting cold-set gels were compared to those of whey protein isolate. Under the chosen heating conditions, most protein was organized in aggregates. For both protein preparations, the aggregates consisted of covalently linked monomers. Both types of protein aggregates had comparable numbers of thiol groups exposed at their surfaces but had clearly different shapes. During acid-induced gelation, the characteristic ordering caused by the repulsive character disappeared and was replaced by a random distribution. This process did not depend on aggregate characteristics and probably applies to any type of protein aggregate. Covalent bonds are the main determinants of the gel hardness. The formation of additional disulfide bonds during gelation depended on the number and accessibility of thiol groups and disulfide bonds in the molecule and was found to clearly differ between the proteins studied. However, upon blocking of the thiol groups, long fibrillar structures of ovalbumin contribute significantly to gel hardness, demonstrating the importance of aggregate shape.  相似文献   

Sulphur immobilization and availability in soils assessed using isotope dilution     

Generose Nziguheba  Erik Smolders  Roel Merckx 《Soil biology & biochemistry》2005,37(4):635-644

Increasing recognition of S deficiency in soils has raised the need for understanding processes governing S cycling and availability in soils. However, the quantification of the two main processes of S cycling, i.e. mineralization and immobilization, remains difficult as these processes occur simultaneously. A modified isotope ³⁵SO₄ dilution technique was developed and used to measure the effect of sulphate (SO₄) fertilization on S mineralization and immobilization in planted (pot experiment with ryegrass (Lolium multiflorum L.)) and unplanted soils (incubation). The immobilization and mineralization of S was calculated from the dynamics of stable and labelled S in soil KH₂PO₄ extracts containing an anion exchange membrane that concentrates SO₄ and mainly excludes other S species. The mathematical analysis of the isotope dilution data differs from methods proposed earlier. The radiolabile S in unplanted soil (E value) and in ryegrass (L value) were used as a measure of total available S in soils. Sulphate immobilization rate significantly declined during incubation. Sulphate application reduced gross mineralization but surprisingly reduced SO₄ immobilization. The E value significantly increased during the incubation in all soils as a result of gross mineralization, e.g. from 3.8 mg S kg⁻¹ at day 0 to 11.5 mg S kg⁻¹ at day 43 in the sandy soil with no sulphate addition. A full recovery in the E value of S added in (+S) treatments was achieved. Similarly, radiolabile S in the above-ground ryegrass biomass (L value) increased with S addition, with a full recovery of added S. The E and L values nearly fit a 1:1 line suggesting identical S dynamics in a planted and unplanted soil. The method proposed has operational advantages compared to methods used earlier.  相似文献   

Opsonization but not pretreatment of equine macrophages with hyperimmune plasma nonspecifically enhances phagocytosis and intracellular killing of Rhodococcus equi     

Aja B. Harvey  Angela I. Bordin  Joana N. Rocha  Jocelyn M. Bray  Noah D. Cohen 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2021,35(1):590-596

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The effects of container geometry on water and heat regimes in soilless culture: lettuce as a case study     

Hadar Heller  Asher Bar-Tal  Shmuel Assouline  Kfir Narkis  Shoshana Suryano  Amandine de la Forge  Mordechai Barak  Hana Alon  Moshe Bruner  Shabtai Cohen  Dov Tsohar 《Irrigation Science》2015,33(1):53-65

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Sap flow in the stem of water stressed soybean and maize plants     

Y. Cohen  M. G. Huck  J. D. Hesketh  J. R. Frederick 《Irrigation Science》1990,11(1):45-50

Summary Water stress was imposed upon soybean [Glyxine max (L.) Merr. cv. Williams] and maize [Zea mays (L.) cv. Pioneer 3377] plants grown under controlled-environment conditions during a growing period of several irrigation cycles. Transpiration rates of individual plants were measured with a calibrated heat-pulse method and correlated to the rate of water loss obtained from successive weighings of the pots containing irrigated or water-stressed plants. Transpiration rate was reduced in the stressed plants of both species, but the reduction was not linear with decreasing soil matric potential. Transpiration rates declined rapidly at high soil matric potential, and dropped more slowly as the soil dried. Although measured transpiration rate declined by nearly 30% following a reduction of soil matric potential to -0.1 MPa, differences in leaf water potential and CO₂ assimilation rate were small and less than the sensitivity of the measurement techniques used. Total system resistance to water flow increased as the soil dried.  相似文献   

ACCURACY OF MAGNETIC RESONANCE IMAGING FOR ESTIMATING INTRAMEDULLARY OSTEOSARCOMA EXTENT IN PRE-OPERATIVE PLANNING OF CANINE LIMB-SALVAGE PROCEDURES     

Seth T.  Wallack  DVM  Erik R.  Wisner  DVM  Jonathan A.  Werner  DVM  Peter J.  Walsh  DVM  Michael S.  Kent  DVM  Robert A.  Fairley  BVSc  William J.  Hornof  DVM  MS 《Veterinary radiology & ultrasound》2002,43(5):432-441

The objective of this work was to compare the accuracy of radiographs and magnetic resonance imaging (MRI) for estimating appendicular osteosarcoma margins. The accuracy of computed tomography (CT) and bone scintigraphy was also assessed when these studies were available. Eight dogs with appendicular osteosarcoma underwent radiographic and MRI of affected limbs. In addition, bone scintigraphy was performed in six dogs and CT examination was performed in five dogs. Two observers jointly measured tumor length on all imaging studies. Correlative gross and histologic evaluation of all affected limbs was performed to determine tumor extent as measured from the nearest articular surface. Results from imaging studies were compared to gross and microscopic morphometry findings to determine the accuracy of each modality for determining tumor boundaries. MRI images were accurate with a mean overestimation of actual tumor length of 3 +/- 13%. T1-weighted non-contrast images were superior in identifying intramedullary tumor margins in most instances whereas contrast-enhanced images provided supplemental information in two dogs. Lateromedial and craniocaudal radiographs overestimated tumor length by 17 +/- 28% and 4 +/- 26%, respectively. Scintigraphy and CT overestimated tumor margins by 14 +/- 28% and 27 +/- 36%, respectively. MRI appears to be an accurate diagnostic imaging modality in determining intramedullary osteosarcoma boundaries. MRI should be considered as part of a pre-operative assessment of appendicular osteosarcoma, particularly when a limb-sparing procedure is contemplated.  相似文献