bluuebunny/crossref_metadata_2025_split huggingface dataset:
Very low prevalence of asthma and allergies in schoolchildren from rural Beijing, China
Authors: Ma Yu , Zhao Jing , Han Z.R. , Chen Yuzhi , Leung Ting F. , Wong Gary W.K. 
Published: July 2009

AbstractBackgroundThe prevalence of asthma is relatively low in the Chinese population. There is consistent evidence that growing up on a farm is associated with protection against the subsequent development of asthma.ObjectiveTo compare the prevalence of asthma in schoolchildren from urban and rural China and to assess the possible protection associated with agricultural and livestock farming.MethodsRandom samples of schoolchildren aged 13–14 years from urban Beijing and rural area around Beijing were studied using the International Study of Asthma and Allergies in Childhood (ISAAC) Phase III protocol. Subjects were studied by questionnaires (n = 7,077) and skin‐prick tests (n = 2,126).ResultsThe prevalence rates of wheeze in the past year and physicians' diagnosis of asthma were 1.0% and 1.1% in the rural area, and these were significantly lower than 7.2% and 6.3% found in the urban children (P < 0.0001). For the video questionnaire, only 0.3% of rural children reported wheeze in the past year compared with 3.1% in urban children (P < 0.0001). Atopy was 3.22 times higher in urban children compared with rural children (P < 0.0001). For rural schoolchildren, 1,453 (41%) have always been living on agricultural farms since birth and the prevalence rates of their asthma symptoms and atopic sensitization were not significantly different from those who have exposed to livestock farming.ConclusionUsing the same validated ISAAC questionnaire and objective skin‐prick tests, the prevalence rates of asthma and atopic sensitization in rural Chinese children were significantly lower than urban children. Exposure to agricultural farming conferred the same protection as livestock farming. Pediatr Pulmonol. 2009; 44:793–799. © 2009 Wiley‐Liss, Inc.
Evaluation of CASP8 model quality predictions
Authors: Cozzetto Domenico , Kryshtafovych Andriy , Tramontano Anna 
Published: July 2009

AbstractThe model quality assessment problem consists in the a priori estimation of the overall and per‐residue accuracy of protein structure predictions. Over the past years, a number of methods have been developed to address this issue and CASP established a prediction category to evaluate their performance in 2006. In 2008 the experiment was repeated and its results are reported here. Participants were invited to infer the correctness of the protein models submitted by the registered automatic servers. Estimates could apply to both whole models and individual amino acids. Groups involved in the tertiary structure prediction categories were also asked to assign local error estimates to each predicted residue in their own models and their results are also discussed here. The correlation between the predicted and observed correctness measures was the basis of the assessment of the results. We observe that consensus‐based methods still perform significantly better than those accepting single models, similarly to what was concluded in the previous edition of the experiment. Proteins 2009. © 2009 Wiley‐Liss, Inc.
Effect of astragaloside IV on hepatic glucose‐regulating enzymes in diabetic mice induced by a high‐fat diet and streptozotocin
Authors: Lv Lin , Wu Shao‐Yu , Wang Guang‐Fa , Zhang Jia‐Jie , Pang Jian‐Xin , Liu Zhong‐Qiu , Xu Wei , Wu Shu‐Guang , Rao Jin‐Jun 
Published: July 2009

AbstractAim: Hepatic glycogen phosphorylase (GP) and glucose‐6‐phosphatase (G6Pase) are important in control of blood glucose homeostasis, and are considered to be potential targets for antidiabetic drugs. Astragaloside IV has been reported to have a hypoglycemic effect. However, the biochemical mechanisms by which astragaloside IV regulates hepatic glucose‐metabolizing enzymes remain unknown. The present study examines whether GP and G6Pase mediate the hypoglycemic effect of astragaloside IV. Methods: Type 2 diabetic mice were treated with astragaloside IV for 2 weeks. Blood glucose and insulin levels were measured by a glucometer and the ELISA method, respectively. Total cholesterol (TC) and triglyceride (TG) levels were determined using LabassayTM kits. Activities of hepatic GP and G6Pase were measured by the glucose‐6‐phosphate dehydrogenase‐coupled reaction. The mRNA and protein levels of both enzymes were determined by real‐time RT‐PCR and Western blotting. Results: Astragaloside IV at 25 and 50 mg/kg significally decreased the blood glucose, TG and insulin levels, and inhibited the mRNA and protein expression as well as enzyme activity of GP and G6Pase in diabetic mice. Conclusions: Astragaloside IV exhibited a hypoglycemic effect in diabetic mice. The hypoglycemic effect of this compound may be explained, in part, by its inhibition of hepatic GP and G6Pase activities. Copyright © 2009 John Wiley & Sons, Ltd.
Effects of active silicon uptake by rice on 29Si fractionation in various plant parts
Authors: Köster Jan Reent , Bol Roland , Leng Melanie J. , Parker Adrian G. , Sloane Hilary J. , Ma Jian F. 
Published: July 2009

AbstractRice (Oryza sativa L.) accumulates large amounts of silicon which improves its growth and health due to enhanced resistance to biotic and abiotic stresses. Silicon uptake and loading to xylem in rice are predominantly active processes performed by transporters encoded by the recently identified genes Lsi1 (Si influx transporter gene) and Lsi2 (Si efflux transporter gene). Silicon deposition in rice during translocation to upper plant tissues is known to discriminate against the heavier isotopes 29Si and 30Si, resulting in isotope fractionation within the plant. We analyzed straw and husk samples of rice mutants defective in Lsi1, Lsi2 or both for silicon content and δ29Si using isotope ratio mass spectrometry (IRMS) and compared these results with those for the corresponding wild‐type varieties (WT). The silicon content was higher in husk than in straw. All the mutant rice lines showed clearly lower silicon content than the WT lines (4–23% Si of WT). The δ29Si was lower in straw and husk for the uptake defective mutant (lsi1) than for WT, albeit δ29Si was 0.3‰ higher in husk than in straw in both lines. The effect of defective efflux (lsi2) differed for straw and husk with higher δ29Si in straw, but lower δ29Si in husk while WT showed similar δ29Si in both fractions. These initial results show the potential of Si isotopes to enlighten the influence of active uptake on translocation and deposition processes in the plant. Copyright © 2009 John Wiley & Sons, Ltd.
Carbon and oxygen isotope microanalysis of carbonate
Authors: Velivetskaya Tatiana A. , Ignatiev Alexander V. , Gorbarenko Sergey A. 
Published: July 2009

AbstractTechnical modification of the conventional method for the δ13C and δ18O analysis of 10–30 µg carbonate samples is described. The CO2 extraction is carried out in vacuum using 105% phosphoric acid at 95°C, and the isotopic composition of CO2 is measured in a helium flow by gas chromatography/isotope ratio mass spectrometry (GC/IRMS). The feed‐motion of samples to the reaction vessel provides sequential dropping of only the samples (without the sample holder) into the acid, preventing the contamination of acid and allowing us to use the same acid to carry out very large numbers of analyses. The high accuracy and high reproducibility of the δ13C and δ18O analyses were demonstrated by measurements of international standards and comparison of results obtained by our method and by the conventional method. Our method allows us to analyze 10 µg of the carbonate with a standard deviation of ±0.05‰ for δ13C and δ18O. The method has been used successfully for the analyses of the oxygen and carbon isotopic composition of the planktonic and benthic foraminifera in detailed palaeotemperature reconstructions of the Okhotsk Sea. Copyright © 2009 John Wiley & Sons, Ltd.
Short‐term dynamics of isotopic composition of leaf‐respired CO2 upon darkening: measurements and implications
Authors: Werner Christiane , Wegener Frederik , Unger Stephan , Nogués Salvador , Priault Pierrick 
Published: July 2009

AbstractRecent advances in understanding the metabolic origin and the temporal dynamics in δ13C of dark‐respired CO2 (δ13Cres) have led to an increasing awareness of the importance of plant isotopic fractionation in respiratory processes. Pronounced dynamics in δ13Cres have been observed in a number of species and three main hypotheses have been proposed: first, diurnal changes in δ13C of respiratory substrates; second, post‐photosynthetic discrimination in respiratory pathways; and third, dynamic decarboxylation of enriched carbon pools during the post‐illumination respiration period. Since different functional groups exhibit distinct diurnal patterns in δ13Cres (ranging from 0 to 10‰ diurnal increase), we explored these hypotheses for different ecotypes and environmental (i.e. growth light) conditions. Mass balance calculations revealed that the effect of respiratory substrates on diurnal changes in δ13Cres was negligible in all investigated species. Further, rapid post‐illumination changes in δ13Cres (30 min), which increased from 2.6‰ to 5‰ over the course of the day, were examined by positional 13C‐labelling to quantify changes in pyruvate dehydrogenase (PDH) and Krebs cycle (KC) activity. We investigated the origin of these dynamics with Rayleigh mass balance calculations based on theoretical assumptions on fractionation processes. Neither the estimated changes of PDH and KC, nor decarboxylation of a malate pool entirely explained the observed pattern in δ13Cres. However, a Rayleigh fractionation of 12C‐discriminating enzymes and/or a rapid decline in the decarboxylation rate of an enriched substrate pool may explain the post‐illumination peak in δ13Cres. These results are highly relevant since δ13Cres is used in large‐scale carbon cycle studies. Copyright © 2009 John Wiley & Sons, Ltd.
Carbon and hydrogen isotope fractionation of benzene during biodegradation under sulfate‐reducing conditions: a laboratory to field site approach
Authors: Fischer Anko , Gehre Matthias , Breitfeld Jana , Richnow Hans‐Hermann , Vogt Carsten 
Published: July 2009

AbstractThe microbial carbon and hydrogen isotope fractionation of benzene under sulfate‐reducing conditions was investigated within systems of increasing complexity: (i) batch laboratory microcosms, (ii) a groundwater‐percolated column system, and (iii) an aquifer transect. Recent molecular biological studies indicate that, at least in the laboratory microcosms and the column system, benzene is degraded by similar bacterial communities. Carbon and hydrogen enrichment factors (εC, εH) obtained from laboratory microcosms and from the column study varied significantly although experiments were performed under similar redox and temperature conditions. Thus, enrichment factors for only a single element could not be used to distinguish benzene degradation under sulfate‐reducing conditions from other redox conditions. In contrast, using correlation of changes of hydrogen vs. carbon isotope ratios (Λ = Δδ2H/Δδ13C), similar Λ‐values were derived for the benzene biodegradation under sulfate‐reducing conditions in all three experimental systems (Λlaboratory microcosms = 23 ± 5, Λcolumn = 28 ± 3, Λaquifer = 24 ± 2), showing the robustness of the two‐dimensional compound‐specific stable isotope analysis (2D‐CSIA) for elucidating distinct biodegradation pathways. Comparing carbon and hydrogen isotope fractionation data from recent studies, an overlap in Λ‐values was observed for benzene biodegradation under sulfate‐reducing (Λ = 23 ± 5 to Λ = 29 ± 3) and methanogenic (Λ = 28 ± 1 to Λ = 39 ± 5) conditions, indicating a similar initial benzene reaction mechanism for both electron‐acceptor conditions. Copyright © 2009 John Wiley & Sons, Ltd.
Consistent patterns in leaf lamina and leaf vein carbon isotope composition across ten herbs and tree species
Authors: Badeck Franz‐W. , Fontaine Jean‐Louis , Dumas Florian , Ghashghaie Jaleh 
Published: July 2009

AbstractWide‐spread post‐photosynthetic fractionation processes deplete metabolites and plant compartments in 13C relative to assimilates to varying degrees. Fragmentation fractionation and exchange of metabolites with distinct isotopic signatures across organ boundaries further modify the patterns of plant isotopic composition. Heterotrophic organs tend to become isotopically heavier than the putative source material as a result of respiratory metabolism. In addition fractionation may occur during metabolite transport across organ and tissue boundaries. Leaf laminae, veins and petioles are leaf compartments that are arranged along a gradient of increasing weight of heterotrophic processes and along a transport chain. Thus, we expect to find consistent patterns of isotopic signatures associated with this gradient. Earlier studies on leaves of Fagus sylvatica, Glycine max, and Saccharum officinarum showed that the organic mass and cellulose of major veins or petioles were consistently more positive than the respective fraction in leaf laminae. The objective of the current study was to assess whether this pattern can be detected in a greater set of plant species. Leaves from ten species were collected in the summer of 2006 outdoors and in glasshouses. Leaf laminae including small veins were separated from the major veins and the isotopic signatures of the organic mass, and the soluble and non‐soluble fractions were measured for laminae and veins separately. The organic mass, and the soluble and non‐soluble fractions of leaf laminae, were depleted in 13C relative to the veins in all cases. A general trend for the signature of organic mass being more depleted in 13C than the soluble fraction is in accordance with well‐known patterns of fractionation between metabolites. Copyright © 2009 John Wiley & Sons, Ltd.
On the application of a ZrO2‐based solid electrolyte in isotope ratio mass spectrometry
Authors: Galimov Eric M. , Sevastyanov Vyacheslav S. , Babulevich Nataliya E. , Tyurina Ekaterina N. 
Published: July 2009

AbstractThe application of a high‐temperature electrochemical reactor based on stabilized zirconium dioxide (0.9 ZrO20.1 Y2O3) for organic gas sampling in continuous‐flow isotope‐ratio mass spectrometry (CF‐IRMS) has been found to be efficient. This solid electrolyte reactor (SER) can also be used as a chromatographic detector for the quantitative measurements of organic gases. A three‐electrode SER system was studied. Complete stoichiometric oxidation of organic gases has been achieved at 900–950°C due to the large catalytic surface area of the porous platinum coating. At this temperature, the oxygen ions formed from the oxygen of ambient air on the outer surface of the reactor migrate through the solid electrolyte under the action of the applied electric field and allow combustion of gases being analyzed to be effected. It should be noted that oxygen gas was not introduced into the gas‐carrier flow. Similar results for the measurements of carbon isotope ratios were obtained at the oxidation of hydrocarbon gases in both the standard and the solid electrolyte reactors. Copyright © 2009 John Wiley & Sons, Ltd.
Contribution of nitrification and denitrification to nitrous oxide emissions from soils after application of biogas waste and other fertilizers
Authors: Senbayram Mehmet , Chen Ruirui , Mühling Karl H. , Dittert Klaus 
Published: July 2009

AbstractThe attribution of nitrous oxide (N2O) emission to organic and inorganic N fertilizers requires understanding of how these inputs affect the two biological processes, i.e. denitrification and nitrification. Contradictory findings have been reported when the effects of organic and inorganic fertilizers on nitrous oxide emission were compared. Here we aimed to contribute to the understanding of such variation using 15N‐labelling techniques. We determined the processes producing N2O, and tested the effects of soil moisture, N rates, and the availability of organic matter. In a pot experiment, we compared soil treated with biogas waste (BGW) and mineral ammonium sulphate (Min‐N) applied at four rates under two soil moisture regimes. We also tested biogas waste, conventional cattle slurry and mineral N fertilizer in a grassland field experiment. During the first 37 days after application we observed N2O emissions of 5.6 kg N2O‐N ha−1 from soils supplied with biogas waste at a rate of 360 kg N ha−1. Fluxes were ca. 5‐fold higher at 85% than at 65% water holding capacity (WHC). The effects of fertilizer types and N rates on N2O emission were significant only when the soil moisture was high. Organic fertilizer treated soils showed much higher N2O emissions than those receiving mineral fertilizer in both, pot and field experiment. Over all the treatments the percentage of the applied N emitted as N2O was 2.56% in BGW but only 0.68% in Min‐N. In the pot experiment isotope labelling indicated that 65–95% of the N2O was derived from denitrification for all fertilizer types. However, the ratio of denitrification/nitrification derived N2O was lower at 65% than at 85% WHC. We speculate that the application of organic matter in conjunction with ammonium nitrogen first leads to a decrease in denitrification‐derived N2O emission compared with soil receiving mineral fertilizer. However, at later stages when denitrification becomes C‐limited, higher N2O emissions are induced when the soil moisture is high. Copyright © 2009 John Wiley & Sons, Ltd.
Kinetic 12C/13C isotope fractionation by invertase: evidence for a small in vitro isotope effect and comparison of two techniques for the isotopic analysis of carbohydrates
Authors: Mauve Caroline , Bleton Jean , Bathellier Camille , Lelarge‐Trouverie Caroline , Guérard Florence , Ghashghaie Jaleh , Tchapla Alain , Tcherkez Guillaume 
Published: July 2009

AbstractThe natural 13C/12C isotope composition (δ13C) of plants and organic compounds within plant organs is a powerful tool to understand carbon allocation patterns and the regulation of photosynthetic or respiratory metabolism. However, many enzymatic fractionations are currently unknown, thus impeding our understanding of carbon trafficking pathways within plant cells. One of them is the 12C/13C isotope effect associated with invertases (EC 3.2.1.26) that are cornerstone enzymes for Suc metabolism and translocation in plants. Another conundrum of isotopic plant biology is the need to measure accurately the specific δ13C of individual carbohydrates. Here, we examined two complementary methods for measuring the δ13C value of sucrose, glucose and fructose, that is, off‐line high‐performance liquid chromatography (HPLC) purification followed by elemental analysis and isotope ratio mass spectrometry (EA‐IRMS) analysis, and gas chromatography‐combustion (GC‐C)‐IRMS. We also used these methods to determine the in vitro 12C/13C isotope effect associated with the yeast invertase. Our results show that, although providing more variable values than HPLC∼EA‐IRMS, and being sensitive to derivatization conditions, the GC‐C‐IRMS method gives reliable results. When applied to the invertase reaction, both methods indicate that the 12C/13C isotope effect is rather small and it is not affected by the use of heavy water (D2O). Copyright © 2009 John Wiley & Sons, Ltd.
The influence of preservation method and time on the δ13C value of dissolved inorganic carbon in water samples
Authors: Taipale Sami J. , Sonninen Eloni 
Published: July 2009

AbstractThe precise δ13C value of dissolved inorganic carbon (DIC) is important for various types of ecological studies. Without a preservation agent, microbial degradation of organic compounds continues in water samples and the δ13C value of DIC will become more depleted with time. HgCl2 or acidification is often used to prevent microbial activity in water samples collected for carbon isotope ratio analyses of DIC. Mercury compounds are toxic and result in waste disposal problems. Other inhibiting agents or preservation methods are therefore needed. Two possible solutions are to use copper sulphate (CuSO4) as a preservative agent or to acidify water samples with phosphoric acid (H3PO4) within 12 mL measurement Exetainers® (septum‐capped vials). We prepared a set of lake water samples in three types of vials: glass vials with silicone/PTFE septa, high‐density polyethylene vials (HD‐PE, scintillation vials) and Exetainers (12 mL) with butyl rubber septa. Samples in glass and PE vials were preserved with and without CuSO4, whereas lake water was injected into the Exetainer and acidified with H3PO4. Isotope ratios were measured in two laboratories over 6 months. The δ13C values of DIC systematically increased with storage time for samples preserved in glass and PE vials with and without CuSO4. A strong correlation between a decrease of CO2 concentration and an increase in DIC δ13C values was found. The δ13C values and DIC concentrations were stable for 6 months in acidified samples stored in Exetainers with butyl rubber septa. Therefore, we conclude that the best method for up to 6 months of storage is to inject samples in the field into butyl rubber septum capped Exetainers® containing H3PO4, thereby avoiding the use of preservatives. Copyright © 2009 John Wiley & Sons, Ltd.
Development and evaluation of a high‐performance liquid chromatography/isotope ratio mass spectrometry methodology for δ13C analyses of amino sugars in soil
Authors: Bodé Samuel , Denef Karolien , Boeckx Pascal 
Published: July 2009

AbstractAmino sugars have been used as biomarkers to assess the relative contribution of dead microbial biomass of different functional groups of microorganisms to soil carbon pools. However, little is known about the dynamics of these compounds in soil. The isotopic composition of individual amino sugars can be used as a tool to determine the turnover of these compounds. Methods to determine the δ13C of amino sugars using gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) have been proposed in literature. However, due to derivatization, the uncertainty on the obtained δ13C is too high to be used for natural abundance studies. Therefore, a new high‐performance liquid chromatography/isotope ratio mass spectrometry (HPLC/IRMS) methodology, with increased accuracy and precision, has been developed. The repeatability on the obtained δ13C values when pure amino sugars were analyzed were not significantly concentration‐dependent as long as the injected amount was higher than 1.5 nmol. The δ13C value of the same amino sugar spiked to a soil deviated by only 0.3‰ from the theoretical value. Copyright © 2009 John Wiley & Sons, Ltd.
Is there any 12C/13C fractionation during starch remobilisation and sucrose export in potato tubers?
Authors: Maunoury‐Danger Florence , Bathellier Camille , Laurette Julien , Fresneau Chantal , Ghashghaie Jaleh , Damesin Claire , Tcherkez Guillaume 
Published: July 2009

AbstractThe δ13C (carbon isotope composition) variations in respired CO2, total organic matter, proteins, sucrose and starch have been measured during tuber sprouting of potato (Solanum tuberosum) in darkness. Measurements were carried out both on tubers and on their growing sprouts for 23 days after the start of sprout development. Sucrose was slightly 13C‐depleted compared with starch in tubers, suggesting that starch breakdown was associated with a small isotope fractionation. In sprouts, all biochemical fractions including sucrose were 13C‐enriched compared with source tuber‐sucrose, suggesting that sucrose translocation from tuber to sprouts fractionated against 12C. However, both apparent fractionations were explained by the consumption of 13C‐depleted carbon for respiration or growth that enriched in the 13C sucrose molecules left behind. In addition, whole tuber sucrose is constantly composed of recent sucrose from starch breakdown and old sucrose associated with an inherited, slightly 13C‐depleted pool. We therefore conclude that any fractionation at either the starch breakdown or the sucrose translocation level is unlikely under our conditions. Copyright © 2009 John Wiley & Sons, Ltd.