bluuebunny/crossref_metadata_2025_split huggingface dataset:
Intima media thickness of carotid arteries is reduced in heterozygous carriers of the Gly972Arg variant in the insulin receptor substrate‐1 gene
Authors: Hölzl B. , Iglseder B. , Stadlmayr A. , Hedegger M. , Moré E. , Reiter R. , Sandhofer F. , Paulweber B. 
Published: March 2003

AbstractBackground The Gly972Arg mutation in the IRS‐1 gene has been found to be associated with insulin resistance and type II diabetes. A recently published study described an association between the Arg allele and an increased risk for coronary artery disease. In the present study we asked whether the presence of the codon 972 mutation in the IRS‐1 gene is associated with higher IMT values of the carotid arteries.Materials and methods To address this question, genotypes of the codon 972 polymorphism were determined in 1018 healthy unrelated individuals aged 40–65 years. Three homozygous carriers of the mutation were excluded for statistical analysis. In all subjects, intima media thickness (IMT) and B‐scores of carotid arteries as well as a large number of metabolic parameters were determined.Results Heterozygous carriers of the Arg972 allele exhibited significantly lower IMT and B‐score values than noncarriers. Total cholesterol, LDL‐cholesterol and serum levels of apolipoprotein B were significantly lower in the carriers. Furthermore, a significant interaction between Gly972Arg‐carrier status and mean daytime 24‐h systolic blood pressure with regard to IMT could be observed; carriers with a systolic blood pressure above the median had lower IMT values than carriers with a systolic blood pressure equal or below the median. All these effects were more pronounced in females and remained significant after adjustment for sex, age, BMI, systolic blood pressure and serum apolipoprotein B levels. No significant differences between the carriers and the noncarriers could be found for BMI, insulin sensitivity or frequency of type II diabetes.Conclusions The results of our study demonstrate that the presence of the Arg972 allele is associated with lower IMT values of the carotid arteries. This finding is partly explained by lower serum levels of apolipoprotein B in carriers. The protective effect of the Gly972 Arg mutation seems to be stronger in the presence of a higher systolic blood pressure. Our data contradict previous findings suggesting an increased risk for insulin resistance, type II diabetes and atherosclerotic vascular disease in carriers of the mutation.
Mannose binding lectin (MBL) genotype distributions with relation to serum levels in UK Caucasoids
Authors: Crosdale D. J. , Ollier W. E. R. , Thomson W. , Dyer P. A. , Jensenious J. , Johnson R. W. G. , Poulton K. V. 
Published: March 2003

AbstractMannose binding lectin (MBL) gene and promoter‐region polymorphisms contribute to a reduction in the levels of circulating MBL in a number of ways. Promoter polymorphisms affect the levels of MBL produced, whilst structurally encoding mutations cause non‐functional protein to be assembled and subsequently degraded. MBL is important as a protein of the innate immune system in both the clearance of potential pathogens and the activation of the complement cascade. Using variations of SSP‐PCR amplifications and SSO probing techniques, we have produced MBL‐polymorphism haplotype and genotype profiles of a series of high‐level MBL‐producing, low‐level MBL‐producing and random individuals taken from a population of 800 UK Caucasoid controls. Structurally encoding mutant alleles were more frequent within the low‐level producing cohort when compared to both high‐level producers and the randomly selected sample. However, not all low‐level producers could be accounted for by the possession of low‐level encoding haplotypes. This may be due to the presence of additional, undetected polymorphisms governing MBL production, or another external factor that may influence the transcriptional regulation of the gene.
Lack of association between HLA genotype and chronic fatigue syndrome
Authors: Underhill J. A. , Mahalingam M. , Peakman M. , Wessely S. 
Published: March 2003

SummaryAlthough the aetiology of chronic fatigue syndrome is controversial, evidence that infective agents including viruses may have a role in the development of the condition has led to studies seeking an association with the immunomodulatory HLA genes. In the present study, we sought to extend previous work using a well‐characterized patient group and modern HLA genotyping techniques. Fifty‐eight patients were phenotyped for HLA A and B by microcytotoxicity and genotyped for HLA DRB, DQB and DPB by PCR oligoprobing, and the frequencies of antigens so assigned were compared with those from a control group of 134. No significant differences in HLA frequencies were found between patient and control groups. Thus, this study does not confirm previous findings of an HLA association with chronic fatigue syndrome, suggesting that neither presentation of viral antigen by HLA class I nor antigen processing genes in the HLA region is a major contributory factor in the development of the disease.
Codominant expression of the polymorphic MICA alloantigens encoded by genes in the HLA region
Authors: Molinero L. L. , Marcos C. Y. , Mirbaha F. , Fainboim L. , Stastny P. , Zwirner N. W. 
Published: March 2003

SummaryThe HLA‐related, polymorphic MHC class I‐related chain A (MICA) gene encodes a 383‐amino acid polypeptide, with three extracellular domains (α1, α2 and α3), a transmembrane region and a cytoplasmic tail. We have previously shown that freshly isolated endothelial cells, fibroblasts, keratinocytes and monocytes express MICA, while peripheral blood CD4+, CD8+or CD19+lymphocytes do not. This polymorphic MICA molecule is a target for specific alloantibodies in sera from kidney, heart and lung transplant recipients, although its possible role during graft rejection remains to be demonstrated. In this study we investigated whether there is codominance in the expression of MICA. We isolated RNA from a heterozygous cell line (HCT116), previously shown by sequencing‐based typing to be MICA*001/MICA*00902, as well as 12 clones derived from it. Thereafter, we retrotranscribed the RNA into cDNA, and performed a molecular typing using MICA‐sequence specific oligonucleotides (SSOP). Using this approach, we detected the RNA encoding MICA*001 and MICA*00902 in all the clones and in the parental cell line, indicating that MICA is codominantly expressed. This codominant expression was further confirmed by cloning and sequencing plasmids encoding these two alleles produced from the same HCT116 RNA preparation. We also produced the two recombinant MICA proteins (MICA*001 and MICA*00902). They reacted with rabbit anti‐MICA polyclonal antibodies by ELISA and Western blot, indicating that the plasmids carrying the cDNA inserts probably encode functional MICA proteins. This strongly suggests that, like the HLA class I and class II proteins, MICA is codominantly expressed. The codominant expression of the polymorphic, HLA‐like MICA alloantigens may have implications for the immune response elicited by the allograft in organ transplantation.
Distribution of bovine lymphocyte antigen (BoLA‐DRB3) alleles in Brazilian dairy Gir cattle (Bos indicus)
Authors: Da Mota A. F. , Gabriel J. E. , Martinez M. L. , Coutinho L. L. 
Published: March 2003

SummaryBrazilian dairy Gir (Bos indicus) cattle are a tropical, well‐adapted breed, for which no information on the major histocompatibility complex (MHC) is presently available. The second exon of the bovine lymphocyte antigen (BoLA‐DRB3) was amplified by polymerase chain reaction (PCR) of DNA samples from 28 Brazilian dairy Gir cows. Two experimental genotyping approaches were used: direct sequencing of PCR gene products (PCR‐DS) and sequencing of cloned PCR fragments (S‐CLO). Results demonstrate the viability of both typing approaches. PCR‐DS allowed typing of 39% of the animals while the remainder were genotyped by S‐CLO. Seventeen BoLA‐DRB3 alleles were assigned, including some that were only recently described for zebu cattle. Allelic frequencies ranged from 0.02 to 0.18. The most frequent alleles were *3601 (frequency = 0.18), *2201 (0.14) and *2101 (0.11).
FcgRIIA, FcγRIIIA and FcγRIIIB polymorphisms in Spanish patients with systemic lupus erythematosus
Authors: González‐Escribano M. F. , Aguilar F. , Sánchez‐Román J. , Núñez‐Roldán A. 
Published: March 2003

SummaryLinkage studies on human families suggest that receptors for the Fc fragments of immunoglobulin G (IgG) (FcγRs) could be implicated in the susceptibility to, or the progression of, some autoimmune diseases. In this work we analyse the possible role of polymorphic variants of FcγRIIA, FcγRIIIA and FcγRIIIB genes in the susceptibility to systemic lupus erythematosus, the prototype systemic autoimmune disease. A total of 276 Spanish patients (34 male and 242 female) with systemic lupus erythematosus were included in this cross‐sectional study. The FcγRIIA‐131, FcγRIIIA‐176 and FcγRIIIB‐NA1/NA2 polymorphisms were investigated in the patient group as well as in 194 ethnically matched controls using polymerase chain reaction–amplification refractory mutation system (PCR‐ARMS). Statistical comparisons of genotype frequencies were performed using the χ2 test. In the case of the FcγRIIIB‐NA1/NA2 polymorphism, an increase in the frequency of homozygous NA2/NA2 in patients was found (61.2 vs. 51.0%; P = 0.03; OR = 1.5; 95% CI = 1.03–2.24), as well as a decrease in the frequency of the NA1/NA2 genotype (28 vs. 38.7%; P = 0.02; OR = 0.6; 95% CI = 0.41–0.92). These associations were independent of patient gender and HLA‐DRB1 specificities. With respect to the FcγRIIA‐131 and FcγRIIIA‐176 polymorphisms, no differences were found between patients and controls. Patient stratification according to their lupus‐related nephritis status gave similar genotypic distribution patterns in both disease categories in all the cases.
Association analysis of polymorphisms in the interleukin‐4 receptor (alpha) gene with atopic asthma in patients from western Mexico
Authors: Mújica‐López K. I. , Flores‐Martínez S. E. , Ramos‐Zepeda R. , Castañeda‐Ramos S. A. , Gazca‐Aguilar A. , García‐Pérez J. , Sánchez‐Corona J. 
Published: March 2003

SummaryWe undertook an association analysis between the ile50val, glu375ala, cys406arg, and ser761pro polymorphisms of the IL‐4Rα gene and atopic asthma, total IgE levels and IL‐4 serum levels in a population from western Mexico. We found that the ser761pro polymorphism was monomorphic for ser761, while there was no association between any of the other polymorphisms and the three phenotypes analysed.
Effects of dissolved organic matter on the mobility of copper in a contaminated sandy soil
Authors: TEMMINGHOFF E. J. M. , VAN DER ZEE S. E. A. T. M. , DE HAAN F. A. M. 
Published: March 2003

SummaryChanges in land use can result in increased soil organic matter content, and decreases in Ca and pH which will affect the mobility of Cu in soil. We studied how the mobility and coagulation of dissolved organic matter and pH affected the mobility of Cu in contaminated sandy soil by batch and column experiments in the laboratory. The soil, with pH ranging from 3.8 to 5.7, had been polluted with Cu in the range 0.13–1.9 mmol kg−1 more than a decade ago. Calcium and Cu bound by dissolved organic matter (purified humic acid) was determined in the pH range 4–8; Cu2+ concentration ranged from 10−4 to 10−12M and Ca2+ concentration from 10−3 to 10−6M. Binding of Cu by dissolved organic matter as affected by Ca and pH could be predicted well with the non‐ideal competitive adsorption (NICA) model. Coagulation of dissolved organic matter was affected by the amount of trivalent (Al3+) and divalent (Ca2+ and Cu2+) cations in solution. There was little effect of pH on coagulation between pH 4 and 6. The concentration of the divalent cations, Ca2+ and Cu2+, at which coagulation of dissolved organic matter appeared could be explained by differences in the binding of Ca and Cu by dissolved organic matter. Binding of Cu by dissolved organic matter as well as by solid organic matter, both affected by Ca and pH, could be described well with the NICA model. We investigated the coagulation and mobility of dissolved organic matter in column experiments and found that they enhanced Cu mobility. Three processes, Cu desorption by soil, dissolved organic matter coagulation and Cu complexation by dissolved organic matter, act simultaneously in the soil columns. All three with counteracting effects on Cu mobility are influenced by Ca and pH and could be adequately represented by the multicomponent NICA model.
A re‐examination of closed flux chamber methods for the measurement of trace gas emissions from soils to the atmosphere
Authors: CONEN F. , SMITH K. A. 
Published: March 2003

SummaryThe most widely used method for measuring the emission of a trace gas such as N2O from soil to the atmosphere involves the accumulation of the gas under closed chambers followed by sampling and analysis (by gas chromatography or infrared methods). These chambers can affect the gas exchange, and so improved designs have been proposed. We have tested their performance. One design includes a vent tube to allow ambient pressure fluctuations to occur also inside the chamber. We tested it against a sealed version on two different grassland sites during N2O peak emissions in spring 1997. On a welldrained soil with a fairly large air permeability vented chambers yielded fluxes as much as five times those of sealed chambers, depending on wind speed. By contrast, on a heavier and wetter soil with smaller air permeability vented chambers averaged only 88% of the fluxes observed with sealed chambers. The effects of venting cannot be explained solely on the basis of mean pressure differences inside and outside the chamber. It seems more likely that wind blowing over the vent depressurizes the chamber (Venturi effect), resulting in significant gas flow from the more permeable soil into the interior of the chamber. The opposite trend for the less permeable soil suggests that diffusion losses through the vent tube are greater than the increase in concentration due to soil gas flow. Venting can create larger errors than the ones it is supposed to overcome.
Characterization of the porous structure of soils: adsorption of nitrogen (77 K) and carbon dioxide (273 K), and mercury porosimetry
Authors: Echeverría J. C. , Morera M. T. , Mazkiarán C. , Garrido J. J. 
Published: March 2003

SummaryAccessibility of adsorbates to internal active sites of soils depends mainly on the porous structure of the material. We aimed to determine the distribution of pore sizes in soils with varied physico‐chemical properties, by combining adsorption of gases and mercury porosimetry. Microporosity was studied by physical adsorption of N2 at 77 K and CO2 at 273 K; mercury intrusion porosimetry allowed us to evaluate the macroporosity; and mesoporosity was determined by capillary condensation of N2 and mercury porosimetry. The soils investigated were essentially macroporous, with volumes between 0.33 and 0.73 cm3 g–1; the maxima in the differential pore‐size distribution were in the range 1500–4000 nm. Volumes of meso‐ or micropores were always less than 10% of macropore volumes. Calculations based on the theory of Dubinin and the αs‐method (for N2 at 77 K) provided, generally, coincident results. In a soil containing much organic matter, N2 adsorption was only one‐ninth that of CO2 adsorption, showing that N2 adsorption into the narrow micropores of organic matter was kinetically restricted. When accessibility to micropores was not restricted, the total volume of micropores could be deduced from N2 adsorption, whereas CO2 measured exclusively the narrowest microporosity.
Blocking the release of potassium from clay interlayers by small concentrations of NH4+ and Cs+
Authors: Springob G. 
Published: March 2003

SummaryTo understand the process and the kinetics of potassium release from the clay interlayer in natural and arable soils in more detail, I tested the hypotheses that large, monovalent cations, especially NH4+ and Cs+, can reduce the release rates of K+ which is exchanged by Ca2+, even if these monovalent cations are present in concentrations of only a few μm. Percolation experiments were carried out with different illitic soil materials, some containing vermiculite, with 5 m
m CaCl2 at pH 5.8 and 20°C, in some cases for over 7000 h.
NH4+ and Cs+ both caused a large decrease in the rate at which K+ was released, Cs+ especially. Suppression began at 5 μm
NH4+ Blocking by 20 μm
NH4+ was easily reversible: the release rates readily increased when
NH4+ was omitted from the exchange solution. Blocking by 2 μm Cs+ was equal to approximately 90% of that at 10 μm Cs+. Larger concentrations of Cs+ than 10 μm did not further reduce release but rather caused a slight increase, probably because of enhanced exchange of K+ by Cs+ without exfoliation of the interlayer space. Blocking by Cs+ was not reversible within > 7000 h of percolation by 5 m
m CaCl2. The blocking effect was reproduced in several different soil materials using 10 μm Cs+ but was most pronounced in vermiculite‐rich samples. As
NH4+ is present in most arable soils, at least in concentrations of a few μm, I conclude that the observed effects are of significance in the K dynamics processes in soils, for example near the roots of plants. Further, very small concentrations of Cs+ in exchange solutions containing a large background of Ca2+ appear to be useful for suppressing K+ release from the interlayer in laboratory studies, probably without significantly altering the exchange at outer mineral surfaces.
Response of sorption processes of MCPA to the amount and origin of organic matter in a long‐term field experiment
Authors: Haberhauer G. , Pfeiffer L. , Gerzabek M. H. , Kirchmann H. , Aquino A. J. A. , Tunega D. , Lischka H. 
Published: March 2003

SummaryChanges in farming practices over long times can affect the sorption behaviour of MCPA ((4‐chloro‐2‐methylphenoxy)acetic acid). We studied the adsorption–desorption mechanisms of MCPA on soil with varied amounts and origins of soil organic matter obtained from a long‐term field experiment with various organic amendments. The origin of the soil organic matter seems to be crucial for the sorption behaviour of MCPA. Samples of soil amended with sewage sludge sorbed MCPA more strongly than the soil under any other treatment. Peat‐amended soil was second followed by soil receiving animal manure, green manure, mineral fertilizer without N and the fallowed soil. Both the carbon content and the origin of the organic matter are important for the sorption. A decrease of carbon content of a soil does not necessarily imply a reduction of sorption capacity for polar organic acids such as MCPA. Nevertheless, our adsorption–desorption experiments suggest that with decreasing carbon content the role of mineral sorption mechanisms could become more pronounced. Our results showed that interactions of soil organic matter and soil minerals distinctly influence adsorption properties for MCPA.
Aggregate strength and mechanical behaviour of a sandy loam soil under long‐term fertilization treatments
Authors: Munkholm L.J. , SchjØnning P. , Debosz K. , Jensen H. E. , Christensen B.T. 
Published: March 2003

SummaryCurrent concern for soil quality has stimulated research on soil biological and chemical properties. In contrast, the mechanical behaviour of soil is somewhat neglected. We have examined the effects on soil mechanical properties of more than 100 years of contrasting fertilization employing three treatments from the Askov long‐term experiment: UNF (unfertilized), NPK (mineral fertilized) and AM (animal manured). We have measured tensile strength of aggregates when air‐dry and when adjusted to −10, −30 and −100 kPa pressure potential. Four aggregate size classes were investigated (1–2, 2–4, 4–8 and 8–16 mm diameter). Soil fragmentation was characterized in the field using a drop‐shatter test. Bulk soil strength was determined in the field using a shear vane and a torsional shear box. Soil texture, pH, cation exchange capacity and microbial biomass were measured. The unfertilized soil has little soil organic matter and microbial biomass and is dense. Its aggregates were strong when dry and weak when wet. In contrast, the manured soil had strong aggregates when wet and rather weak ones when dry. The NPK soil generally had intermediate properties. The differences between the soils when dry seem to be related to differences in dispersible clay content, whereas the differences when wet are related to differences in the amount of organic binding and bonding material. The optimal water content for tillage as well as the tolerable range in water content was largest in the manured soil and smallest in the unfertilized soil. Our results indicate that soil mechanical properties should be measured over a range of water regimes to determine the effects of various long‐term fertilization treatments.
Effect of rain on the macroporosity at the soil surface
Authors: Rousseva S. , Torri D. , Pagliai M. 
Published: March 2003

SummaryRain falling on soil causes slaking, mechanical disruption of aggregates and compaction. Too few data exist to predict the changes likely to occur in particular soil, landscape and management conditions. Experiments with simulated rain were set up to study and to model mathematically the changes of the pore system within the surface layer of a soil when rain was applied on a field cropped with maize. Macroporosity, pore‐size and pore‐shape distributions, and the pore volume were measured by image analysis of thin sections and the fractal dimensions of the pore surface roughness were estimated. The general trends of changes in porosity indicated the presence of two different sets of processes at the surface (0–3 cm) and in the layer immediately underneath (3–6 cm). In both layers most of the variation in macroporosity was due to a loss of elongated porosity. A theoretical approach recently developed to link rain and erosion to sealing properties was extended to describing the effect of rain on the elongated porosity and the pore volume fractal dimension in these two layers. The resulting set of equations describe in detail the evolution of soil porosity near the soil surface. Our approach could be useful when modelling the effects of sealing processes in soil erosion.
The isotopic composition of soil organic carbon on a north–south transect in western Canada
Authors: Bird M. , Santrùcková H. , Lloyd J. , Lawson E. 
Published: March 2003

SummaryThe minor isotopes of carbon (13C and 14C) are widely used as tracers in studies of the global carbon cycle. We present carbon‐isotope data for the 0–5 cm layer of soil on a transect from 49.6°N to 68°N, from mature forest and tundra ecosystems in the boreal‐arctic zone of interior western Canada. Soil organic carbon in the < 2000 μm fraction of the soil decreases from 3.14 kg m−2 in the south to 1.31 kg m−2 in the north. The 14C activity of the organic carbon decreases as latitude increases from 118.9 to 100.7 per cent modern carbon (pMC). In addition, the 14C activities of organic carbon in the particle‐size fractions of each sample decrease as particle size decreases. These results suggest that organic carbon in the 0–5 cm layer of these soils transfers from standing biomass into the coarsest size fractions of the soil and is then degraded over time, with the residue progressively transferred into the more resistant finer particle sizes. We calculate residence times for the coarsest size fractions of 21 years in the south to 71 years in the north. Residence times for the fine size fractions (< 63 μm) are considerably longer, ranging from 90 years in the south to 960 years in the north. The δ13C of the organic carbon decreases from −26.8 ± 0.3‰ in soil under forest in the south to −26.2 ± 0.1‰ for tundra sites in the north. At all sites there is an increase in δ13C with decreasing particle size of 0.7–1.6‰. These changes in δ13C are due to the presence of ‘old’ carbon in equilibrium with an atmosphere richer in 13C, and to the effects of microbial degradation.