bluuebunny/crossref_metadata_2025_split huggingface dataset:
Patterns of co‐occurrence of three single nucleotide polymorphisms of the 5,10‐methylenetetrahydrofolate reductase gene in kidney transplant recipients
Authors: Winkelmayer W. C. , Sunder‐Plassmann G. , Huber A. , Födinger M. 
Published: September 2004

AbstractBackground  Recently, a new mutation of the 5,10‐methylenetetrahydrofolate reductase (MTHFR) encoding gene was first described (1793G > A). Only few reports have studied the prevalence of this polymorphism, especially in combination with other MTHFR mutations (677C > T, 1298A > C).Methods  We cross‐sectionally identified the novel MTHFR 1793G > A polymorphism in 730 kidney transplant recipients. MTHFR 677C > T and 1298A > C were also assessed and the frequency of each was described individually as well as in cross‐tabulation with the other MTHFR genotypes. The expected number of patients for each MTHFR genotype combination was calculated and contrasted with the observed numbers. Fisher's exact test was used for statistical inference.Results  The allelic frequency of MTHFR 1793G > A was 0·052. Seventy‐two patients (9·9%) were heterozygous and two patients (0·3%) were homozygous. From the cross‐tabulations, we identified 53 patients (expected: 33·6) with the MTHFR 1298AC/1793GA genotype and 17 patients (expected: 6·7) with the MTHFR 1298CC/1793GA genotype. Furthermore, we found two patients with double homozygosity for MTHFR 1793G > A and MTHFR 1298A > C (MTHFR 1793AA/1298CC genotype). The frequencies of these genotype combinations were substantially larger than could be expected (P < 0·001).Conclusions  These findings suggest a selection or survival advantage for individuals with combined MTHFR 1793G > A and MTHFR 1298A > C genotypes, possibly owing to a mutually stabilizing effect on MTHFR enzyme activity.
Mechanism of in vitro heme‐induced LDL oxidation: effects of antioxidants
Authors: Klouche K. , Morena M. , Canaud B. , Descomps B. , Beraud J. J. , Cristol J. P. 
Published: September 2004

AbstractBackground  Heme protein toxicity, owing to generation of reactive oxygen species most likely by direct interaction between heme iron and hydrogen peroxide (H2O2), may be involved in various pathologies, including atherogenesis and pigmentary acute renal failure. The aim of this study was to investigate the mechanism of heme cytotoxicity and the effects of antioxidant therapies in an in vitro model of heme‐induced low‐density lipoprotein (LDL) oxidation.Materials and methods  Human LDLs were exposed to heme, iron (Fe), protoporphyrin (PPIX) and PPIX‐Zinc (Zn) with or without H2O2. Lipid peroxidation was monitored by measurement of conjugated diene formation (at the 234‐nm absorbance). The effect of various antioxidants, such as vitamin E and vitamin C, reduced glutathione (GSH), and oxidized glutathione (GSSG), mannitol and desferoxamine (DFO) was further investigated in the established in vitro model of LDL oxidation.Results  Incubation of LDLs in the presence of heme/H2O2 induced lipid peroxidation with the optimal oxidation rate being at 5 µm heme/100 µm H2O2 doses. By contrast, incubation of LDL with H2O2, Fe, Fe/H2O2, PPIX, PPIX/H2O2, heme or PPIX‐Zn did not initiate any LDL oxidation. In vitro, the vitamin E load protected native LDLs against heme/H2O2 oxidative modifications. Incubation of LDLs with increasing doses of vitamin C, GSH and DFO conferred a dose‐dependent protection, while mannitol and GSSG had no effect.Conclusions  Initiation and propagation of heme‐induced lipid peroxidation is not mediated by a Fenton reaction but depends on specific interactions between heme and H2O2. It may result from the generation of ferryl and perferryl radicals derived from hemic Fe and H2O2 interactions. A protective effect of vitamins E, C, GSH and DFO was demonstrated in this model.
Effect of transition metal ions (cobalt and nickel chlorides) on intestinal iron absorption
Authors: Latunde‐Dada G. O. , Shirali S. , McKie A. T. , Simpson R. J. , Peters T. J. 
Published: September 2004

AbstractBackground  Haem biosynthesis may regulate intestinal iron absorption through changes in cellular levels of δ‐aminolaevulinic acid (ALA), haem and perhaps other intermediates. CoCl2 and NiCl2 are activators of haem oxygenase, the rate‐limiting enzyme in haem catabolism. Co2+ and Ni2+ may also regulate and increase iron absorption through a mechanism that simulates hypoxic conditions in the tissues.Design  We assayed intestinal iron absorption in mice dosed with CoCl2 or NiCl2. The effects of these metal ions on splenic and hepatic levels of ALA synthase and dehydratase as well as urinary levels of ALA and phosphobilinogen were also assayed.Results  While Co2+ enhanced iron absorption when administered to mice at doses of 65, 125 and 250 µmoles kg−1 body weight, Ni2+ was effective only at the highest dose. Ni2+ but not Co2+ at the highest dose reduced urinary ALA in the treated mice. Both metals ions increased splenic expression of haem oxygenase 1 and iron regulated protein 1, proteins involved, respectively, in haem degradation and iron efflux. Co2+ induced erythropoietin expression.Conclusions  The data suggest that while the effect of Ni2+ on iron absorption could be explained by effects on ALA, the effect of Co2+ may not be explained simply by changes in haem metabolism; therefore, effects mediated by alterations of specific haemoproteins by mechanisms that simulate tissue hypoxia could be important.
Effects of experimentally imposed climate scenarios on flowering phenology and flower production of subarctic bog species
Authors: Aerts R. , Cornelissen J. H. C. , Dorrepaal E. , Van Logtestijn R. S. P. , Callaghan T. V. 
Published: September 2004

AbstractClimate scenarios for high‐latitude areas predict not only increased summer temperatures, but also larger variation in snowfall and winter temperatures. By using open‐top chambers, we experimentally manipulated both summer temperatures and winter and spring snow accumulations and temperatures independently in a blanket bog in subarctic Sweden, yielding six climate scenarios. We studied the effects of these scenarios on flowering phenology and flower production of Andromeda polifolia (woody evergreen) and Rubus chamaemorus (perennial herb) during 2 years. The second year of our study (2002) was characterized by unusually high spring and early summer temperatures.Our winter manipulations led to consistent increases in winter snow cover. As a result, average and minimum air and soil temperatures in the high snow cover treatments were higher than in the winter ambient treatments, whereas temperature fluctuations were smaller. Spring warming resulted in higher average, minimum, and maximum soil temperatures. Summer warming led to higher air and soil temperatures in mid‐summer (June–July), but not in late summer (August–September).The unusually high temperatures in 2002 advanced the median flowering date by 2 weeks for both species in all treatments. Superimposed on this effect, we found that for both Andromeda and Rubus, all our climate treatments (except summer warming for Rubus) advanced flowering by 1–4 days. The total flower production of both species showed a more or less similar response: flower production in the warm year 2002 exceeded that in 2001 by far. However, in both species flower production was only stimulated by the spring‐warming treatments.Our results show that the reproductive ecology of both species is very responsive to climate change but this response is very dependent on specific climate events, especially those that occur in winter and spring. This suggests that high‐latitude climate change experiments should focus more on winter and spring events than has been the case so far.
The growth respiration component in eddy CO2 flux from a Quercus ilex mediterranean forest
Authors: Rambal S. , Joffre R. , Ourcival J. M. , Cavender‐Bares J. , Rocheteau A. 
Published: September 2004

AbstractEcosystem respiration, arising from soil decomposition as well as from plant maintenance and growth, has been shown to be the most important component of carbon exchange in most terrestrial ecosystems. The goal of this study was to estimate the growth component of whole‐ecosystem respiration in a Mediterranean evergreen oak (Quercus ilex) forest over the course of 3 years. Ecosystem respiration (Reco) was determined from night‐time carbon dioxide flux (Fc) using eddy correlation when friction velocity (u*) was greater than 0.35 m s−1We postulated that growth respiration could be evaluated as a residual after removing modeled base Reco from whole‐ecosystem Reco during periods when growth was most likely occurring. We observed that the model deviated from the night‐time Fc‐based Reco during the period from early February to early July with the largest discrepancies occurring at the end of May, coinciding with budburst when active aboveground growth and radial growth increment are greatest. The highest growth respiration rates were observed in 2001 with daily fluxes reaching up to 4 g C m−2. The cumulative growth respiration for the entire growth period gave total carbon losses of 170, 208, and 142 g C m−2 for 1999, 2001, and 2002, respectively. Biochemical analysis of soluble carbohydrates, starch, cellulose, hemicellulose, proteins, lignin, and lipids for leaves and stems allowed calculation of the total construction costs of the different growth components, which yielded values of 154, 200, and 150 g C for 3 years, respectively, corresponding well to estimated growth respiration. Estimates of both leaf and stem growth showed very large interannual variation, although average growth respiration coefficients and average yield of growth processes were fairly constant over the 3 years and close to literature values. The time course of the growth respiration may be explained by the growth pattern of leaves and stems and by cambial activity. This approach has potential applications for interpreting the effects of climate variation, disturbances, and management practices on growth and ecosystem respiration.
Effect of elevated [CO2] on stem wood properties of mature Norway spruce grown at different soil nutrient availability
Authors: Kostiainen Katri , Kaakinen Seija , Saranpää Pekka , Sigurdsson Bjarni D. , Linder Sune , Vapaavuori Elina 
Published: September 2004

AbstractThe objective of the present study was to investigate the interactive effects of elevated [CO2] and soil nutrient availability on secondary xylem structure and chemical composition of 41‐year‐old Norway spruce (Picea abies (L.) Karst.) trees. The nonfertilized and irrigated‐fertilized trees were, for 3 years, continuously exposed to elevated [CO2] in whole‐tree chambers. Elevated [CO2] decreased concentrations of soluble sugars, acid‐soluble lignin and nitrogen in stem wood, but the effects were not consistent between sampling height and/or fertilization. The effect of 2*ambient [CO2] on wood structure depended on the exposure year and/or fertilization. Radial lumen diameter decreased and annual ring width increased in the second year of exposure (1999) in elevated [CO2]. In the latter, the CO2 effect was significant only in the nonfertilized trees. Stem wood chemistry and structure were significantly affected by fertilization. Fertilization increased the concentrations of nitrogen and gravimetric lignin, annual ring width, and radial lumen diameter. Fertilization decreased C/N ratio, mean ring density, earlywood density, latewood density, cell wall thickness, cell wall index, and latewood percentage. We conclude that elevated [CO2] had only minor effects on wood properties while fertilization had more marked effects and thus may affect ecosystem processes and suitability of wood for different end‐use purposes.
Disturbance and climate effects on carbon stocks and fluxes across Western Oregon USA
Authors: Law B. E. , Turner D. , Campbell J. , Sun O. J. , Van Tuyl S. , Ritts W. D. , Cohen W. B. 
Published: September 2004

AbstractWe used a spatially nested hierarchy of field and remote‐sensing observations and a process model, Biome‐BGC, to produce a carbon budget for the forested region of Oregon, and to determine the relative influence of differences in climate and disturbance among the ecoregions on carbon stocks and fluxes. The simulations suggest that annual net uptake (net ecosystem production (NEP)) for the whole forested region (8.2 million hectares) was 13.8 Tg C (168 g C m−2 yr−1), with the highest mean uptake in the Coast Range ecoregion (226 g C m−2 yr−1), and the lowest mean NEP in the East Cascades (EC) ecoregion (88 g C m−2 yr−1). Carbon stocks totaled 2765 Tg C (33 700 g C m−2), with wide variability among ecoregions in the mean stock and in the partitioning above‐ and belowground. The flux of carbon from the land to the atmosphere that is driven by wildfire was relatively low during the late 1990s (∼0.1 Tg C yr−1), however, wildfires in 2002 generated a much larger C source (∼4.1 Tg C). Annual harvest removals from the study area over the period 1995–2000 were ∼5.5 Tg C yr−1. The removals were disproportionately from the Coast Range, which is heavily managed for timber production (approximately 50% of all of Oregon's forest land has been managed for timber in the past 5 years). The estimate for the annual increase in C stored in long‐lived forest products and land fills was 1.4 Tg C yr−1. Net biome production (NBP) on the land, the net effect of NEP, harvest removals, and wildfire emissions indicates that the study area was a sink (8.2 Tg C yr−1). NBP of the study area, which is the more heavily forested half of the state, compensated for ∼52% of Oregon's fossil carbon dioxide emissions of 15.6 Tg C yr−1 in 2000. The Biscuit Fire in 2002 reduced NBP dramatically, exacerbating net emissions that year. The regional total reflects the strong east–west gradient in potential productivity associated with the climatic gradient, and a disturbance regime that has been dominated in recent decades by commercial forestry.
Would climate change drive species out of reserves? An assessment of existing reserve‐selection methods
Authors: Araújo Miguel B. , Cabeza Mar , Thuiller Wilfried , Hannah Lee , Williams Paul H. 
Published: September 2004

AbstractConcern for climate change has not yet been integrated in protocols for reserve selection. However if climate changes as projected, there is a possibility that current reserve‐selection methods might provide solutions that are inadequate to ensure species' long‐term persistence within reserves. We assessed, for the first time, the ability of existing reserve‐selection methods to secure species in a climate‐change context. Six methods using a different combination of criteria (representation, suitability and reserve clustering) are compared. The assessment is carried out using European distributions of 1200 plant species and considering two extreme scenarios of response to climate change: no dispersal and universal dispersal. With our data, 6–11% of species modelled would be potentially lost from selected reserves in a 50‐year period. Measured uncertainties varied in 6% being 1–3% attributed to dispersal assumptions and 2–5% to the choice of reserve‐selection method. Suitability approaches to reserve selection performed best, while reserve clustering performed poorly. We also found that 5% of species modelled would lose their entire climatic envelope in the studied area; 2% of the species modelled would have nonoverlapping distributions; 93% of the species modelled would maintain varying levels of overlapping distributions. We conclude there are opportunities to minimize species' extinctions within reserves but new approaches are needed to account for impacts of climate change on species; especially for those projected to have temporally nonoverlapping distributions.
Airway hyper‐reactivity mediated by B‐1 cell immunoglobulin M antibody generating complement C5a at 1 day post‐immunization in a murine hapten model of non‐atopic asthma
Authors: Kawikova Ivana , Paliwal Vipin , Szczepanik Marian , Itakura Atsuko , Fukui Mieko , Campos Regis A. , Geba Gregory P. , Homer Robert J. , Iliopoulou Bettina P. , Pober Jordan S. , Tsuji Ryohei F. , Askenase Philip W. 
Published: September 2004

SummaryContact skin immunization of mice with reactive hapten antigen and subsequent airway challenge with the same hapten induces immediate airflow obstruction and subsequent airway hyper‐reactivity (AHR) to methacholine challenge, which is dependent on B cells but not on T cells. This responsiveness to airway challenge with antigen is elicited as early as 1 day postimmunization and can be adoptively transferred to naïve recipients via 1‐day immune cells. Responses are absent in 1‐day immune B‐cell‐deficient JH−/− mice and B‐1 B‐cell‐deficient xid male mice, as well as in recipients of 1‐day immune cells depleted of cells with the B‐1 cell phenotype (CD19+ B220+ CD5+). As B‐1 cells produce immunoglobulin M (IgM), we sought and found significantly increased numbers of anti‐hapten IgM‐producing cells in the spleen and lymph nodes of 1‐day immune wild‐type mice, but not in xid mice. Then, we passively immunized naive mice with anti‐hapten IgM monoclonal antibody and, following airway hapten challenge of the recipients, we showed both immediate airflow obstruction and AHR. In addition, AHR was absent in complement C5 and C5a receptor‐deficient mice. In summary, this study of the very early elicited phase of a hapten asthma model suggests, for the first time, a role of B‐1 cells in producing IgM to activate complement to rapidly mediate asthma airway reactivity only 1 day after immunization.
A novel adjuvant–allergen complex, CBP–rFel d 1, induces up‐regulation of CD86 expression and enhances cytokine release by human dendritic cells in vitro
Authors: Andersson Theresa N. , Ekman Gunilla J. , Grönlund Hans , Buentke Eva , Eriksson Tove L. J. , Scheynius Annika , Van Hage‐Hamsten Marianne , Gafvelin Guro 
Published: September 2004

SummaryAllergen‐specific immunotherapy is commonly performed with allergen extracts adsorbed to aluminium hydroxide (alum). The undesirable effects associated with the use of alum, including granuloma formation at the site of injection and stimulation of T helper 2 (Th2) cytokine production, has generated interest in alternative allergen carriers, one being carbohydrate‐based particles (CBPs). Here, we have investigated the in vitro effects of the recombinant major cat allergen Fel d 1 (rFel d 1) coupled to CBPs (CBP–rFel d 1) on human monocyte‐derived dendritic cells (MDDCs) obtained from healthy blood donors. A majority of the CD1a+ MDDCs internalized fluorescein isothiocyanate‐labelled CBP–rFel d 1, as demonstrated by flow cytometry and confocal laser‐scanning microscopy. Furthermore, an up‐regulation of the expression of the costimulatory molecule, CD86, on the MDDCs was induced by CBP–rFel d 1, but not by rFel d 1 or CBPs alone. Finally, three‐ and fourfold increases in the release of interleukin‐8 and tumour necrosis factor‐α, respectively, were observed when MDDCs were cultured in the presence of CBP‐rFel d 1. Altogether, our results indicate that the use of CBPs as an allergen carrier and adjuvant is a promising candidate for the improvement of allergen‐specific immunotherapy.
Effects of a cysteinyl leukotriene receptor antagonist on eosinophil recruitment in experimental allergic rhinitis
Authors: Saito Hiroko , Morikawa Hiroshi , Howie Karen , Crawford Lynn , Baatjes Adrian J. , Denburg Elisha , Cyr Michael M. , Denburg Judah A. 
Published: September 2004

SummaryThe cysteinyl leukotrienes (cysLTs) are potent lipid mediators in allergic disease, acting through a receptor (cysLT1‐R) which can be targeted in rhinitis and asthma. We investigated the effects of cysLT1‐R antagonism in experimental allergic rhinitis, focusing on bone marrow eosinophil progenitor responses. BALB/c mice were sensitized, then given daily intranasal ovalbumin for 2 weeks, with montelukast sodium (5 mg/kg or 2·5 mg/kg) or placebo by gavage. Bone marrow eosinophil/basophil colonies were enumerated, and colony cells were morphologically assessed as indices of eosinophil differentiation and maturation. Montelukast treatment resulted in a significant decrease of eosinophils in the nasal mucosa, and in either bone marrow interleukin (IL)‐5‐, but not IL‐3‐, or granulocyte‐macrophage colony‐stimulating factor‐responsive eosinophil/basophil colony‐forming units, and IL‐5‐stimulated eosinophil maturation. These results indicate that cysLT1‐R antagonism in vivo limits both IL‐5‐responsive eosinophilopoiesis, acting at several stages of eosinophil differentiation and maturation. The anti‐allergic effects of cysLT1‐R antagonists are consistent with the concept that cysLTs and IL‐5 act together in the recruitment of eosinophils and eosinophil progenitors from the marrow during upper airway allergic inflammation.
Lycopene suppresses the lipopolysaccharide‐induced phenotypic and functional maturation of murine dendritic cells through inhibition of mitogen‐activated protein kinases and nuclear factor‐κB
Authors: Kim Gi‐Young , Kim Jong‐Hyun , Ahn Soon‐Cheol , Lee Hee‐Jeong , Moon Dong‐Oh , Lee Chang‐Min , Park Yeong‐Min 
Published: September 2004

SummaryDendritic cells (DC) are the most potent of antigen‐presenting cells. The most important function of DC is to initiate the immune response by presenting antigens to naïve T lymphocytes. Currently, little is known about the basic action of lycopene in murine bone marrow (BM)‐derived DC. In the present study, we have revealed that lycopene significantly attenuates the phenotypic and functional maturation of murine BM‐DC, especially in lipopolysaccharide‐induced DC maturation. We found that lycopene down‐regulates the expression of costimulatory molecules (CD80 and CD86) and major histocompatibility complex type II molecules. We also determined that lycopene‐treated DC were poor stimulators of naïve allogeneic T‐cell proliferation and induced lower levels of interleukin‐2 in responding T cells. They also exhibited impaired interleukin‐12 production. Additionally, lycopene was able to inhibit mitogen‐activated protein kinases, such as ERK1/2, p38 and JNK, and the transcription factor, nuclear factor‐κB. Assessment of the in vivo effects of lycopene may reveal an inability to induce a normal cell‐mediated immune response, despite the ability of the cells to migrate to the spleen. This data provides new insight into the immunopharmacology of lycopene and suggests a novel approach to the manipulation of DC for therapeutic application.