bluuebunny/crossref_metadata_2025 huggingface dataset:
The effects of acetylsalicylic acid on proliferation, apoptosis, and invasion of cyclooxygenase‐2 negative colon cancer cells
Authors: Yu H.‐G. , Huang J.‐A. , Yang Y.‐N. , Huang H. , Luo H.‐S. , Yu J.‐P. , Meier J. J. , Schrader H. , Bastian A. , Schmidt W. E. , Schmitz F.
Published: March 2003

Background Acetylsalicylic acid (ASA, aspirin), the most common nonsteroidal anti‐inflammatory drug (NSAID), has been shown to have a protective effect against the incidence and mortality of colorectal cancer. However, the mechanism of its anticancer function remains unclear. The aim of this study was to determine the effects of acetylsalicylic acid on proliferation, apoptosis, and invasion in human cyclooxygenase‐2 (COX‐2) negative colorectal cancer cell lines.

Materials and Methods After treatment with various concentrations of ASA, cell proliferation was measured in the human colon cancer cell line SW480. Apoptotic cells were identified by transmission electron microscopy, acridine orange staining, and flow cytometry. The invasive potential of SW480 cells was detected using an in vitro invasion assay. The production of carcinoembryonic antigen was measured by microparticle enzyme immunoassay. Expression of Bcl2, Bax, CD44v6, and nm23 were evaluated by immunocytochemistry.

Results ASA significantly inhibited the proliferation of SW480 cells and stimulated apoptosis. Production of carcinoembryonic antigen and the invasive potential of SW480 cells were also inhibited by ASA. After treatment with ASA, down‐regulation of Bcl2 and CD44v6 expression and up‐regulation of nm23 expression were observed in SW480 cells. No obvious effect of ASA was found on Bax expression.

Conclusion Our findings reveal that ASA inhibits the proliferation and promotes apoptosis in the human colon cancer cell line SW480. Down‐regulation of Bcl2 expression might represent a potential mechanism by which ASA induces apoptosis in this COX‐2 negative colon cancer cell line. Our results also suggest that ASA decreases the invasive potential of these colon cancer cells. Decreased CEA content and CD44v6 expression and elevated nm23 expression may contribute to the effect of ASA on invasive potential of SW480 colon cancer cells.
Association between increased levels of IL‐2 and IL‐15 and outcome in patients with early acute respiratory distress syndrome
Authors: Agouridakis P. , Kyriakou D. , Alexandrakis M. G. , Perisinakis K. , Karkavitsas N. , Bouros D.
Published: March 2003

Background Acute respiratory distress syndrome remains a serious, often fatal, condition, despite progress in modern critical care treatment. Cytokines play an important role in the pathogenesis of the syndrome, although their role in the evolution and outcome has not been clearly elucidated. We explored whether the measurement of serum and bronchoalveolar lavage IL‐2 and IL‐15 at the time of hospital admission can predict the outcome of this syndrome.

Methods Serum and bronchoalveolar lavage levels of IL‐2 and IL‐15 were measured in eight patients with ARDS (group A) and 26 patients on high risk for ARDS development who never developed ARDS (group B) from samples obtained at the time of admission.

Results Serum IL‐2 (P > 0·05) and IL‐15 (P < 0·05) levels were higher in group A than in group B. Serum levels of both cytokines were higher in patients who did not survive in both of the groups A and B compared to those who survived (P < 0·05, and P < 0·0001, respectively). The only significant change in BALF was the higher level of IL‐15 in surviving group A patients (P < 0·05) when compared with the non survivors of the same group. For a serum cut‐off level of 173 pg mL−1 for IL‐2 and 250 pg mL−1 for IL‐15, they exhibited a very high positive predictive value (PPV), negative predictive value (NPV), sensitivity and specificity for survival (100% in all). A positive correlation was found between serum levels of both cytokines and APACHE II score (IL‐2, r = 0·61, and IL‐15, r = 0·62, respectively, and P < 0·0001 for both).

Conclusion Determination of serum IL‐2 and IL‐15 levels may be a valuable and simple aid to improve identification of patients with ARDS or at risk for ARDS who are at high risk of subsequent mortality.
Ferric saccharate induces oxygen radical stress and endothelial dysfunction in vivo
Authors: Rooyakkers T. M. , Stroes E. S. G. , Kooistra M. P. , Van Faassen E. E. , Hider R. C. , Rabelink T. J. , Marx J. J. M.
Published: March 2003

Background  Intravenous iron supplementation is used widely in haemodialysis patients. However, nontransferrin‐bound iron (NTBI), which increases after intravenous supplementation of ferric saccharate, has been suggested to act as a catalytic agent in oxygen radical formation in vitro and may thus contribute to endothelial impairment in vivo.

Materials and methods  In 20 healthy volunteers the effect of 100 mg ferric saccharate infusion was investigated. Vascular ultrasound was used to assess endothelium‐dependent vasodilatation at baseline, and 10 and 240 min after ferric saccharate infusion. Whole blood was collected to measure NTBI and in vivo radical formation was assessed by electron spin resonance. A time‐control study was performed using saline infusion.

Results  Infusion of ferric saccharate induces a greater than fourfold increase in NTBI, as well as a transient, significant (P < 0·01) reduction of flow‐mediated dilatation 10 min after infusion of ferric saccharate, when compared with saline. The generation of superoxide in whole blood increased significantly 10 and 240 min after infusion of ferric saccharate by, respectively, 70 and 53%.

Conclusions  Iron infusion at a currently used therapeutic dose for intravenous iron supplementation leads to increased oxygen radical stress and acute endothelial dysfunction.
Nature of nontransferrin‐bound iron
Authors: Hider R. C.
Published: March 2003

Nontransferrin‐bound iron is now recognized to exist by many workers. It is present in the serum of patients suffering from a wide range of disease states and may be induced by certain therapeutic treatments. The chemical nature of this iron pool is unknown but almost certainly it is a multicomponent pool including a considerable proportion of protein‐bound iron. Methods are required to separate and quantify these different components. The biological properties of the individual isoforms need to be established; it is possible that some forms are relatively nontoxic, while others are highly toxic. This paper reviews what is known about the nature of nontransferrin‐bound iron and describes the methods currently available to quantify this important serum component.
Human immunodeficiency virus type 1 replication inhibition by the bidentate iron chelators CP502 and CP511 is caused by proliferation inhibition and the onset of apoptosis
Authors: Georgiou N. A. , Van Der Bruggen T. , Oudshoorn M. , Hider R. C. , Marx J. J. M. , Van Asbeck B. S.
Published: March 2003

Background

The iron chelators deferoxamine (DF) and deferiprone (CP20) have been shown to inhibit human immunodeficiency virus type 1 (HIV‐1) replication in human peripheral blood lymphocytes (PBL). The orally active bidentate chelators CP502 and CP511, which also belong to the 3‐hydroxypyridin‐4‐one family, but with higher affinities for iron than CP20, were monitored for their antiviral properties by checking for p24 antigen production and nuclear factor (NF)‐κB activation, and their ability to induce apoptosis.

Materials and methods Human PBLs were isolated from HIV‐1 seronegative donors and subsequently infected with HIV‐1Ba‐L for 2 h. After 5 days’ incubation, HIV‐1 replication was monitored by p24 antigen production. Cellular proliferation as well as caspase‐3 activity were monitored in uninfected cells after a period of 5 days and after 1 day infection, respectively. NF‐κB activity was also monitored by electromobility shift assays (EMSA) performed on nuclear extracts of Jurkat cells treated with the different chelators for 4 h.

Results CP502 and CP511 decrease HIV‐1 replication by decreasing cellular proliferation in a similar manner to DF and CP20. CP511 seemed to be more potent than either CP502 or CP20. Due to the reduction in cellular proliferation, there was an increase in caspase‐3 activity after 24 h incubation. NF‐κB activity was not affected by any of the chelators.

Conclusions Iron chelators with high affinities for iron, which are under development for the treatment of iron overload, could contribute to the reduction of HIV‐1 replication in infected patients by cellular proliferation inhibition rather than by a direct antiviral action.
Dinucleotide repeat polymorphisms within the Flt‐1 gene in minimal change nephropathy
Authors: Parry R. G. , Gillespie K. M. , Clark A. G. B. , Mathieson P. W.
Published: March 2003

Dysregulation of Flt‐1, a major receptor for vascular permeability factor (VPF), may provide a mechanism for the development of proteinuria in minimal change nephropathy (MCN). The gene for Flt‐1 has a polymorphic dinucleotide repeat. We have demonstrated an 88% predominance of one allele and an 80% rate of homozygosity for this polymorphism with no association with MCN.
Identification of seven new TCRBV subfamilies in cattle (Bos taurus)*
Authors: Houston E. F. , Morrison W. I.
Published: March 2003

In cattle, the repertoire of TCRBV genes that encode the variable region of T‐cell receptor β‐chains has not been fully characterized. In this study, cattle TCRBV genes were amplified from mRNA by anchored polymerase chain reaction and sequenced. Eleven new TCRBV gene sequences were found, and classified into seven subfamilies distinct from those previously identified.
Analysis of deletions in three McLeod patients: exclusion of the XS locus from the Xp21.1–Xp21.2 region
Authors: Nemer Wassim El , Colin Yves , Collec Emmanuel , Gane Pierre , Cartron Jean Pierre , Le Van Kim Caroline
Published: March 2003

The McLeod syndrome is a rare X‐linked recessive disorder characterized by blood group, neuromuscular and haematopoietic abnormalities. It is caused by XK gene defects and may include large deletions in the Xp21 region. Analysis of three unrelated McLeod patients for the presence of the XK, DMD, CYBB, ETX1, RPGR and OTC loci, as well as for the DXS709 marker, revealed deletions from the 39th exon of DMD to the ETX1 locus (patient Be), from the XK to RPGR loci (patient Bi) and from the XK to CYBB loci (patient Lh). All three patients normally expressed the Lutheran (Lu) red cell antigens, thus excluding the interval between the RPGR and DMD genes as site of the XS locus, previously mapped to the Xp21.2–Xq21.1 region and thought to regulate the expression of the LU blood group gene on chromosome 19.
CTLA4 exon 1 dimorphism in bullous and cicatricial pemphigoid
Authors: Drouet M. , Aupetit C. , Delpuget‐Bertin N. , Bedane C. , Bonnetblanc J. M. , Cogné M.
Published: March 2003

The human cytotoxic T‐lymphocyte antigen 4 (CTLA4) gene encodes proteins regulating the immune response. The polymorphism of this gene is associated with some autoimmune diseases. In this study, we analysed the distribution of the dimorphisms of exon 1 (+ 49 A/G) in bullous pemphigoid (BP) and cicatricial pemphigoid (CP), two types of autoimmune bullous skin diseases that occur in elderly people. The frequency of the exon 1 A‐G genotype was marginally decreased in patients (36.4%; n = 55) compared with controls (52.8%, n = 53), but the results were not statistically significant (P = 0.09).
HLA antigen and gene frequencies in Eskimos of East Greenland
Authors: Welinder L. , Graugaard B. , Madsen† M.
Published: March 2003

A population of 78 Ammassallik Eskimos was tested for HLA‐A, B, Cw, DR and DQ specificities using serological techniques and HLA‐Cw, DRB, DQB1 and DPB1 using three different genomic techniques. The application of two new genomic techniques for HLA‐Cw (PCR‐SSP phototyping) and HLA‐DPB1 (PCR‐RLFP) typing confirmed serological results and gave a higher resolution, with more heterozygotes than previously found. High gene frequencies of HLA‐A24 (0.80), B51 (0.21), B61 (0.30), B62 (0.21), Cw*0303 (0.27), Cw*0304 (0.51), DRB1*0401 (0.45), DRB1*1402 (0.24), DQ7 (0.88), DPB1*0201 (0.18), DPB1*0401 (0.40) and DPB1*0402 (0.30) were found. A limited number of alleles were found at all HLA loci. The Ammassallik Eskimos of East Greenland are genetically homogenous with little, if any, admixture with European populations. This contrasts with other Greenlandic populations formerly tested. The pattern of alleles indicates a close genetic relationship with other Eskimo populations.
The genomic organization of the mouse CD94 C‐type lectin gene
Authors: Lohwasser S. , Wilhelm B. , Mager D. L. , Takei F.
Published: March 2003

The mouse natural killer (NK) gene complex is located on chromosome 6 and contains a number of genes encoding C‐type lectin receptors which have been found to regulate NK cell function. Among these are CD94 and four NKG2 genes. Like its human counterpart, the mouse CD94 protein associates with different NKG2 isoforms and recognizes the atypical MHC class I molecule Qa‐1b. Here, the genomic organization of the mouse CD94 gene was determined by analysing a BAC clone containing the CD94 gene. The mouse CD94 gene contains six exons separated by five introns. Exons I and II encode the 5′ untranslated region (UTR) and the transmembrane domain. Exon III encodes the stalk region and exons IV–VI encode the carbohydrate recognition domain (CRD). Furthermore, we cloned and sequenced the CD94 promoter region, and putative regulatory DNA elements were identified. Further studies on the CD94 promoter region may help to elucidate the restricted expression pattern of CD94 in NK cells and a subpopulation of T cells.
Lymphocyte antigens in sheep: linkage to the MHC class II DRB1 gene
Authors: Jugo B. M. , Vicario A.
Published: March 2003

In this work a typing battery of sera was developed to test lymphocyte antigens in sheep. Eight antigens were detected in a Latxa sheep sample. The serological determination of these antigens is described. As some of the detected antigens segregated in close linkage with class II DRB1 SSCP patterns in two half‐sib families, we can conclude that they are coded by genes located in the MHC. Gene frequencies were very similar in Latxa Mutur Gorria and Latxa Mutur Beltza, the two varieties of the Latxa breed. Although few animals were typed in the comparison with other typing sera, it seems that two of our sera clusters detect the same antigens as those detected by other research groups working in other breeds with their own typing batteries.
Characterization of Peromyscus MHC class II beta sequences by ligation‐anchored RT‐PCR and denaturing gradient gel electrophoresis
Authors: Richman A. D. , Herrera L. G. , Nash D.
Published: March 2003

We characterized MHC class II beta sequences in deermice (genus Peromyscus), which are amongst the most common mammals in North America. We find evidence for two different families of class II beta loci, most closely related to either the A‐type or E‐type loci in Mus. Population studies suggest the presence of more than one A‐type locus but only one E‐type locus for the species investigated.
Recombinant DRB sequences produced by mismatch repair of heteroduplexes during cloning in Escherichia coli
Authors: Longeri M. , Zanotti M. , Damiani G.
Published: March 2003

Recombinant chimeric sequences originating from a mixture of the sequences of two different alleles are frequently found after amplification and cloning in Escherichia coli of exon 2 of the major histocompatibility complex (MHC) DRB genes. Several authors have suggested that the recombinant molecules result from in vitro recombination during PCR; nevertheless, a clear experimental demonstration of this hypothesis is lacking. In order to understand the mechanism producing the chimeric sequences, we set up a simple experiment based on the different restriction patterns of parental and recombinant sequences. Our data demonstrate that in the analysed case most of the recombinant variants were not produced by in vitro recombination during PCR, but were the result of the mismatch repair of heteroduplex molecules during cloning in E. coli. The high mutation rate in the α‐helix region of DRB expressed genes, both after cloning in E. coli and after the germ‐line differentiation process in vertebrates, suggests that the observed mutations are the result of similar gene conversion processes, probably favoured by chi‐dependent microrecombination events.
Extractability and dissolution kinetics of pure and soil‐added synthesized aluminium hydroxy sulphate minerals
Authors: PRIETZEL J. , HIRSCH C.
Published: March 2003

Various extractants used in current analytical procedures for the fractionation of sulphur (S) in soils were compared with respect to their ability to dissolve Al hydroxy sulphate minerals of defined composition (basaluminite, K alunite, mixtures of basaluminite and Na alunite). The minerals were synthesized and aged in the laboratory at 20°C and 50°C. The dissolution kinetics at 20°C of these Al hydroxy sulphates in deionized water, 0.02M HCl and 0.02M NaOH were also investigated.

The dissolution stability of the Al hydroxy sulphate minerals increased in the order basaluminite < K alunite < Na alunite. The dissolving power of the reagents used increased in the order H2O ≤ 0.016M KH2PO4≪ 0.02M HCl ≈ acidic NH4 oxalate ≈ 0.5M NaHCO3 < Na2 CO3/NaHCO3 < 0.1M NH4F < 0.5M NH4F < 0.05M NaOH ≤ 0.05M LiOH. In Al hydroxy sulphate‐containing soils, inorganic S is probably understimated and ester sulphate S overestimated, if the inorganic S pool is assessed by extraction with KH2PO4, Ca(H2PO4)2 or NaHCO3 solutions. The dissolution of all studied Al hydroxy sulphates, particularly that of K and Na alunite, in H2O and 0.02 M HCl is strongly delayed by kinetic restraints. Thus it seems unlikely that Al3+ or SO2−4 activites in soil solutions are strictly regulated by precipitation/dissolution equilibria of these minerals except for horizons with extraordinarily slow seepage water movement.
Influence of the nature of clay minerals on the fixation of radiocaesium traces in an acid brown earth–podzol weathering sequence
Authors: Maes E. , Iserentant A. , Herbauts J. , Delvaux B.
Published: March 2003

The magnitude of radiocaesium fixation by micaceous clay minerals is affected by their transformation, which depends on weathering in soil. The net retention of radiocaesium traces was quantified by sorption–desorption experiments in the various horizons of four sandy soils forming an acid brown earth–podzol weathering sequence derived from sandy sediments and characterized by marked changes in mineral composition. The features of the 2:1 minerals of the four soils, resulting from an aluminization process in depth and a desaluminization process towards the surface, had a strong influence on Cs+fixation. Beneath the desaluminization front, which deepens from the acid brown earth to the podzol, hydroxy interlayered vermiculite was dominant and the137Cs+fixation was the weakest. At the desaluminization front depth, vermiculite was responsible for the strongest137Cs+fixation. In the upper layers, smectite appeared in the podzolized soils and the137Cs+fixation decreased. The magnitude in Cs+fixation therefore appeared as a tracer of the transformation process affecting the 2:1 clay minerals in the acid brown earth–podzol weathering sequence. This magnitude was positively correlated with the vermiculite content of the studied soil materials estimated by the rubidium saturation method.
Molecular characteristics related to the biodegradability of humic acid preparations
Authors: Almendros G. , Dorado J.
Published: March 2003

The resistance of soil humic material in soil seems to depend on its molecular characteristics. We have studied 12 chemically modified humic samples in mineral soil to identify molecular characteristics connected with their resistance to biodegradation. The treatments, used to introduce changes in the composition, reactivity and N content of the original humic acid (HA), consisted of acetylation, amidation, methylation, nitration, oximation, sulfonation, acid and alkaline hydrolysis, hydrogen peroxide oxidation and fixation of ammonia and of stearic acid. The relations between respirometric data (total mineralization coefficient and mineralization rates at different stages of the 85‐day mineralization curve) and a series of HA characteristics (wet chemical analyses, spectroscopic data and relative yields of different pyrolysis products) were examined by correlation and by multiple regression models.

The structural characters of HA most directly related to the susceptibility to biodegradation were the concentration of O–alkyl structures and oxygen content mainly in phenolic structures. The aliphatic/aromatic ratio showed no significant correlation with the resistance of organic matter. The fact that the yields of lignin‐derived pyrolysis compounds were directly related to carbon mineralization suggested that the structural contribution of domains consisting of preserved biomacromolecules is more important than the neat aromaticity of the HA.

The multiple regression models suggested that molecular size of the HA had the greatest influence in the early mineralization stages, whereas the characteristics of the C backbone (concentration of O–alkyl and alkyl carbons) had a greater influence in the advanced transformation stages in the soil.

The lack of significant correlations with N concentration indicated that native N forms as well as N‐containing groups introduced in peat HA did not have a measurable trophic effect on the biodegradation. The disordered macromolecular structure of the HAs seems to play a greater role in their resistance to biodegradation than the relative amounts of their major structural constituents.
Effect of water tension on ethylene production and consumption in montane and lowland soils in Austria
Authors: Zechmeister‐Boltenstern S. , Nikodim L.
Published: March 2003

The trace gas ethylene affects plant growth and atmospheric chemistry and it interferes with soil restoration. In soil ethylene is simultaneously produced and consumed by different microorganisms. The effects of land use and soil moisture conditions on processes leading to an accumulation of ethylene are still unclear. We measured the rates at which montane and lowland soils from Austria produced and consumed ethylene over a range of water tensions and oxygen supply. Complete anaerobiosis (waterlogging, zero tension) favoured ethylene production, whereas ethylene degradation rates were greatest in soils at 30 kPa water tension. Soils from the lowland region of eastern Austria produced ethylene at rates of up to 12 pmol C2H4g–1 h–1under anaerobic conditions, and they consumed ethylene at rates reaching 231 pmol C2H4g–1 h–1, after addition of 20 μl l–1ethylene. Deciduous forest soils consumed ethylene fastest. Ethylene formed rapidly and was also consumed rapidly in soils rich in humus and total nitrogen. Soils taken from the mountains both produced and consumed ethylene more rapidly than lowland soils did. Production rates reached 146 pmol C2H4g–1 h–1under anaerobic conditions. Spruce forest soils produced significantly more ethylene than pastures. Ethylene formation was negatively correlated with soil pH. In montane soils ethylene production was related to the availability of simple carbon sources, expressed by the amount of extractable glucose equivalents. Maximum ethylene degradation amounted to 895 pmol g–1 h–1. Most of the soils were net sinks for ethylene at a water tension of 30 kPa and drier.
Water‐soluble organic matter in incipient podzols: accumulation in B horizons or in fibres?
Authors: Nierop K. G. J. , Buurman P.
Published: March 2003

To elucidate the mechanism of podzolization in its first stages we studied the fate of the water‐soluble organic matter (WSOM) in incipient podzols in sandy soils by comparing the composition of the WSOM from L, F and H horizons with that in the bulk of the Bh horizons and fibres of three profiles. The WSOM appeared to consist significantly of ligno‐cellulose and proteins, but these biopolymers were hardly present in the Bh horizons. The material of the fibres, however, greatly resembled the WSOM composition, thereby suggesting that in these soils most of the WSOM is transported through the B horizon and accumulates hardly changed in thin bands where the water stops moving. This implies that in the early steps of podzolization, accumulation of organic matter in the B horizon is not likely to be caused by water‐soluble material.
Decalcification of soils subject to periodic waterlogging
Authors: Van Den Berg G. A. , Loch J. P. G.
Published: March 2003

Intense decalcification of fine‐grained organic‐rich soils subject to periodic oxidation and reduction takes place in the Biesbosch, a freshwater, tidally influenced wetland area in the Rhine–Meuse delta in The Netherlands. Soil chemical (sulphide concentration and pore‐water characteristics) and hydrological variables (drainage) were measured in three representative Fluvisols differing in hydrology to identify processes inducing calcium carbonate dissolution. Both oxidation of previously formed iron sulphides during periods of low ground water and infrequent inundation, and increased carbon dioxide pressure in the soil during periods of waterlogging combined with drainage of pore‐water solutes, contribute significantly to decalcification of the hydric soils. The effects of these individual processes on decalcification are in the same order of magnitude in the studied soils. Depending on site‐specific hydrological conditions, approximately 0.1–0.3% calcium carbonate may be dissolved per year by a combination of these two processes, which is comparable to actual decalcification rates at these sites. Estimates of long‐term decalcification rates, based on knowledge of the hydrogeochemistry, may be used to assess the risks accompanying the conversion of agricultural soils into wetlands.
Estimation of soil weathering stage and acid neutralizing capacity in a toposequence Luvisol–Cambisol on loess under deciduous forest in Belgium
Authors: Brahy V. , Deckers J. , Delvaux B.
Published: March 2003

Soils derived from loess are extensive in Europe and are well suited for forestry. They are suspected to be poor acid buffers, however. We have estimated the weathering stage and acid neutralizing capacity of acid soils under forest in a toposequence on loess in the Belgian silt belt. The soils vary distinctly in morphology and physico‐chemical properties according to their topographic position. Dystric Cambisols have developed in colluvial deposits in the dry valley floors, whereas Dystric Luvisols have formed on the slopes in a rejuvenated material. The Cambisols are more acid and less saturated in bases than are Luvisols. They are strongly depleted of clay and contain less weatherable minerals. Easily weatherable minerals are concentrated mainly in the clay fraction of both soil types. Clay minerals of size < 2 μm therefore act as major sinks for protons in these soils. A simplified expression taking into account the total reserve in bases, total aluminium and iron occluded in silicates is used to estimate acid neutralizing capacity. Our estimates confirm that these acid loessic soils are indeed poor acid buffers. They show that the Dystric Cambisols depleted of clay are sensitive to potential acidification, whether natural or man‐made.
A cation exchange index for assessing degradation of acid soil by further acidification under permanent agriculture in the tropics
Authors: Noble A. D. , Gillman G. P. , Ruaysoongnern S.
Published: March 2003

Soil acidification and related land degradation are becoming more important worldwide and are challenging the concept of sustainability of current land management systems. We have studied the impact on soil properties of two management systems, one in a tropical savanna, the other in a humid subtropical environment, particularly in relation to their cation chemistry. In Northeast Thailand the properties of an Acrisol cleared of dipterocarp forest some 37 years previously and used for continuous crop production are compared with adjacent undisturbed forest. In southern Queensland, Australia, the properties of a Luvisol used for intensive pasture production for 36 years are compared with those prior to introduction of the management system. Under both regimes, the soil pH fell by about 1 unit, with an increase in aluminium saturation of the cation exchange complex. Organic carbon in the Acrisol greatly decreased, but in the Luvisol it increased significantly. Consequently, the effects on surface charge characteristics were strikingly different, in that the Acrisol had been almost irreversibly degraded, whereas acidification and base diminution in the Luvisol can be easily reversed through conventional management. The amount of degradation caused by each management system has been quantified in terms of a Saturation Index, Su:

S
u = 100 × (Cu5.5 − Σ)/Cu5.5,

where Cu5.5 refers to the cation exchange capacity on the undisturbed (forested) site and Σ is the sum of the base cations at field pH. This index encompasses an assessment of the degree of degradation taking into account the previous land use, in this case forest, and that due to anthropogenic disturbance. For the Queensland Luvisol Su does not change, because the pasture management has not appreciably altered the CEC at pH 5.5. However, for the Thailand site Su increased from 0 to 86%. Consequently in its present state, the surface horizon of this cultivated soil can retain only about 15% of the basic cations it could ideally hold under undisturbed conditions.
A mono‐component model of carbon mineralization with a dynamic rate constant
Authors: Yang H. S. , Janssen B. H.
Published: March 2003

The difficulties in using complicated models of carbon mineralization and the poor performance of simple ones call for new models that are simple in use and robust in performance. We have developed a model for the mineralization of carbon from experimental data in which the organic matter is treated as a single component. The logarithm of the average relative mineralization rate, K, or rate constant, of a substrate considered as a whole was found to be linearly related to the logarithm of time, t, provided prevailing soil conditions remained unchanged. The equation is: logK = logR–S logt, or K = R t–S, in which R (dimension tS − 1) represents K at t = 1, and S (dimensionless, 1 ≥ S≥ 0) is a measure of the rate at which K decreases over time, also called the speed of ‘ageing’ of the substrate. The quantity of the remaining substrate, Yt, is calculated by Yt = Y0 exp(–Rt1 – S), where Y0 is the initial quantity of the substrate. The actual relative mineralization rate, k, at time t is proportional to K, according to k = (1 − S)K. The model was tested against an assembly of 136 sets of data collected from trials conducted in 14 countries all over the world. They cover materials ranging from glucose, cellulose and plant residues, to farmyard manure, peat and soil organic matter. The results lead to the conclusion that the model describes well the dynamics of organic matter in soil over time varying from months to tens of years, provided major environmental conditions remain unchanged. It can easily be applied in practice and is attractive because of its modest input requirements.
Field‐scale run‐off and erosion in relation to topsoil aggregate stability in three tropical regions (Benin, Cameroon, Mexico)
Authors: Barthès B. , Azontonde A. , Boli B. Z. , Prat C. , Roose E.
Published: March 2003

The influence of aggregate stability on run‐off and erosion has often been reported from experiments on microplots (about 1 m2) under simulated rain. Our objective was to compare the aggregate stability of topsoil (0–10 cm) with run‐off and erosion from experiments on run‐off plots (about 100–1000 m2) under natural rain. Run‐off and soil losses were measured over three years on 14 plots in Benin, Cameroon and Mexico. All plots were under herbaceous vegetation and had moderate slope length and slope declivity, but differed in climate (400–1600 mm annual rainfall), soil type (sandy clay loam Nitosol, loamy sand Ferralsol, loamy Regosol), and management (from savanna to long‐duration mouldboard ploughing). The stability of aggregates was determined by immersing and wet‐sieving 2‐mm sieved air‐dried samples into water.

Mean annual run‐off rate and soil losses generally increased, and the proportion of stable macroaggregates (> 0.2 mm) decreased, with increasing duration and intensity of tillage, and with decreasing cover on the soil surface. For all 14 plots, run‐off and soil losses were closely correlated with aggregate stability; correlations were improved when slope gradient and climate aggressivity were considered in addition to aggregation. Slaking, the main mechanism of aggregate breakdown which occurs when dry soil is immersed, accounted well for run‐off and erosion. The stability of topsoil aggregates seems therefore to be a valuable indicator of field‐assessed run‐off and erosion for plots on moderate slopes with herbaceous vegetation.
A laboratory method for measuring the isotropic character of soil swelling
Authors: Michel J. ‐C. , Beaumont A. , Tessier D.
Published: March 2003

Although the swelling of clays has been thoroughly studied, the mechanism by which this occurs in clay soils is not so fully understood. We have developed a technique to study the swelling and three‐dimensional deformation of a soil sample during wetting by adapting a triaxial apparatus. This equipment applies a controlled, confined and isotropic pressure to the periphery of the samples. A constant flow of solution is injected into the base of the sample while the lateral and axial deformations are simultaneously controlled. The development of the interstitial pressure, positive or negative, is measured. When the soil is thoroughly wetted, the equipment measures the saturated hydraulic conductivity.

The swelling of the soil is not necessarily isotropic, and practically all the possibilities of lateral, isotropic and vertical swelling can be encountered. Furthermore, the swelling can be preceded by significant lateral shrinkage, caused by fissures. The results show the importance of confinement pressure when measuring the swelling of the samples.

The adaptation of a triaxial apparatus to the study of the permeability and swelling of soils appears to be promising as it also allows the geometric development of the samples to be traced as well as the changes in the chemical composition of the percolating solutions.
Non‐equilibrium water flow characterized by means of upward infiltration experiments
Authors: Šimůnek J. , Wendroth O. , Wypler N. , Van Genuchten M. T.
Published: March 2003

Upward infiltration experiments under tension were used to demonstrate the presence of non‐equilibrium flow in soils, the phenomenon that has important implications for the accelerated movement of fertilizers, pesticides, non‐aqueous liquids, and other pollutants. Data obtained from these experiments were analysed using the single‐porosity Richards equation, as well as a variably saturated, dual‐porosity model and a dual‐permeability model for characterizing non‐equilibrium water flow. The laboratory experiments were carried out on 0.10‐m‐long soil cores having an internal diameter of 0.10 m. Constant pressure heads of −0.10 and −0.01 m were used as the lower boundary condition. Each infiltration was followed by a single‐rate evaporation experiment to re‐establish initial conditions, and to obtain the drying soil hydraulic properties. Pressure heads inside the cores were measured using five tensiometers, while evaporative water loss from the top was determined by weighing the soil samples. The data were analysed to estimate parameters using a technique that combined a numerical solution of the governing flow equation (as implemented in a modified version of the Hydrus‐1D software) with a Marquardt–Levenberg optimization. The objective function for the parameter estimation was defined in terms of pressure head readings, the cumulative infiltration rate, and the final total water volume in the core during upward infiltration. The final total water volume was used, as well as the pressure head readings during the evaporation part. Analysis of flow responses obtained during the infiltration experiment demonstrated significant non‐equilibrium flow. This behaviour could be well characterized using a model of physical non‐equilibrium that divides the medium into inter‐ and intra‐aggregate pores with first‐order transfer of water between the two systems. The analysis also demonstrated the importance of hysteresis.
Abandoned anthills of Formica polyctena and soil heterogeneity in a temperate deciduous forest: morphology and organic matter composition
Authors: Kristiansen S. M. , Amelung W.
Published: March 2003

Ants can modify the properties of soil when they build their nests. We have investigated the degree and persistency of changes of soil morphology and chemistry in abandoned anthills in a temperate, deciduous wood in Jutland, Denmark. For this purpose, we sampled surface soils (0–10 cm) from each of five abandoned anthills (Formica polyctenaFörster) and adjacent undisturbed sites, where anthills covered about 0.5% of the surface area. In addition, one soil profile in an abandoned anthill was sampled for morphological descriptions. All samples were analysed for pH, C, N, lignin‐derived phenol, and cellulosic and non‐cellulosic carbohydrate concentrations. The results showed that soils under the anthills were enriched in organic matter, were yellower and showed features of Podzol degradation. Former Podzols had to be reclassified to Umbrisols or Arenosols, whereas anthills on Luvisols affected soil classification only at the subdivision level. The C/N ratio and soil pH were not significantly affected by the ants' activity. However, lignin‐derived phenols and cellulosic polysaccharides were enriched inside the mounds by a factor of 6 and 7, respectively. This probably reflected collection of woody debris for nest construction while the nest was occupied, and large input of C from an increased root density. The degree of changes in the quality of the organic matter decreased with time since abandonment, but changes were still detectable within anthills left 20 years ago. As ant colonies are concentrated, and move regularly on a decadal timescale, formation ofFormicaanthills has an intrinsic influence on the heterogeneity of the soil within this forest ecosystem.
Interpretation of heteronuclear and multidimensional NMR spectroscopy of humic substances
Authors: Simpson A. J. , Burdon J. , Graham C. L. , Hayes M. H. B. , Spencer N. , Kingery W. L.
Published: March 2003

Mapping the chemical structures and organization of humic substances is vital for a fundamental understanding of their roles and interactions in the soil. One‐dimensional nuclear magnetic resonance (NMR) techniques have advanced our awareness of the composition of humic materials, but modern developments in two‐dimensional NMR are soon likely to make obsolete reliance on one‐dimensional spectra alone. The advantages of using heteronuclear two‐dimensional NMR spectroscopy are illustrated in this paper in studies of the structural units in a fulvic acid fraction isolated from the Bh horizon of a Podzol.

The structures identified from the NMR (at 500 MHz) experiments can be summarized as: mono‐ and dicarboxylic acids (in about equal amounts), with an average chain length of about 10 carbon atoms (these are easily the major components); smaller amounts (about 10–20% of the acids) of esters and alcohols or ethers; some carbohydrate and amino acid residues (evidence from chemical shift data would suggest that these were likely to be in the form of chains); and very small amounts of 1,2‐, 1,4‐, and 1,3,4‐substituted benzenes and of cinnamic acids. The results suggest that applications of heteronuclear and multidimensional NMR spectroscopy will allow considerable progress to be made in understanding the nature of the structural units and their connectivities in humic molecules provided that the heterogeneity of the humic mixtures can first be decreased significantly.
Description and classification of soil structure using distance transform data
Authors: Holden N. M.
Published: March 2003

Classification of soil based on structure is useful for conveying information about physical properties and soil processes. The distance transform is an image analysis technique suitable for quantifying soil structure. An analysis of distance transform data, in the form of cumulative area distribution curves for previously published images of soil structures of various types, is presented. The images were used to derive a quantitative classification of structure using maximum distance of solid from a macropore (Dmax, measured), the distance from macropore space containing 50% of the solid area (k, derived by fitting a sigmoidal function to the cumulative area distribution curve), the total interface length between pore and solid per area of sample (IA, measured), the porosity or the proportion of pores per area of sample (PA, measured) and the pore distribution characteristic (n, derived by fitting a sigmoidal function to the cumulative area distribution curve) which is related to the number, continuity and distribution of pores. The influence of image resolution was investigated, and within limits found to be fairly small. The final classification of soil structure was based on the hypothesized relations between the descriptors and structure‐forming processes.
Changes in variance and correlation of soil properties with scale and location: analysis using an adapted maximal overlap discrete wavelet transform
Authors: Lark R. M. , Webster R.
Published: March 2003

The magnitude of variation in soil properties can change from place to place, and this lack of stationarity can preclude conventional geostatistical and spectral analysis. In contrast, wavelets and their scaling functions, which take non‐zero values only over short intervals and are therefore local, enable us to handle such variation. Wavelets can be used to analyse scale‐dependence and spatial changes in the correlation of two variables where the linear model of coregionalization is inadmissible.

We have adapted wavelet methods to analyse soil properties with non‐stationary variation and covariation in fairly small sets of data, such as we can expect in soil survey, and we have applied them to measurements of pH and the contents of clay and calcium carbonate on a 3‐km transect in Central England. Places on the transect where significant changes in the variance of the soil properties occur were identified. The scale‐dependence of the correlations of soil properties was investigated by calculating wavelet correlations for each spatial scale. We identified where the covariance of the properties appeared to change and then computed the wavelet correlations on each side of the change point and compared them. The correlation of topsoil and subsoil clay content was found to be uniform along the transect at one important scale, although there were significant changes in the variance. In contrast, carbonate content and pH of the topsoil were correlated only in parts of the transect.
Rock weathering promoted by embryonic soils in surface cavities
Authors: Certini G. , Corti G. , Ugolini F. C. , De Siena C.
Published: March 2003

The upper surfaces of trachyte outcrops and boulders in Tuscany and Latium have numerous cavities. The cavities have formed from the dislodgement of xenoliths and, if properly oriented, they collect water and accumulate mineral and organic debris. There is no drainage, and water stays in them for a long time, inducing a severe hydrological regimen, but supporting a variety of living organisms such as cyanobacteria, green algae and insects. The humic substances produced by the humification of organic matter and the organic acids released by organisms alter the underlying rock, thereby deepening and enlarging the cavities. Following the dissolution of the glassy cements, crystals detach from the matrix to join the accumulated material, where they are progressively comminuted and partly changed into clay minerals. With time, these accumulations increase in thickness sufficiently to allow the establishment of vascular plants and the development of horizons so as to become embryonic soils. We sampled the material from several such cavities and determined its chemical and mineralogical composition. We conclude that cavities contain miniature ecosystems supported by the tiny bodies of soil in them.
Spatial and temporal variations in resistance of loess‐derived soils to ephemeral gully erosion
Authors: Nachtergaele J. , Poesen J.
Published: March 2003

Planners would like a simple means of describing spatial and temporal variations in soil erodibility accurately. We have done a series of concentrated flow detachment experiments to investigate the feasibility. Four different soil horizons, typical of loess‐derived soils in Belgium, were sampled seven times during one year, so that a representative range of initial soil moisture contents was obtained. Undisturbed soil samples were subjected to five different combinations of slope gradient and concentrated flow discharge. Results showed that for a given soil horizon, variations in detachment rate could be related well to temporal variations in initial soil moisture content. For a given initial soil moisture content the ploughed topsoil horizon (Ap) and the underlying clay‐enriched horizon (Bt) had only one fifth of the erodibility of the loess horizon whether decalcified (C1) or still calcareous (C2). Combining knowledge on spatial distribution of soil profiles and initial soil moisture content allowed us to explain observed spatial and temporal variations in resistance to ephemeral gully erosion for soils in loess. Also, differences in ephemeral gully morphology (cross‐sections) could be explained from differences in initial soil moisture content and soil horizon. In the short term these results have important implications for spatial and temporal variations in erosion, while in the medium or long term information on spatial distribution of soil profiles is crucial when predicting the volumes and patterns of (ephemeral gully) erosion. Finally, the importance of combining the effect of water and tillage erosion with respect to soil profile evolution and consequent erosion risk is stressed.
The inherent ‘safety‐net’ of an Acrisol: measuring and modelling retarded leaching of mineral nitrogen
Authors: Suprayogo D. , Van Noordwijk M. , Hairiah K. , Cadisch G.
Published: March 2003

The inherent features of Acrisols with their increasing clay content with depth are conducive to reducing nutrient losses by nutrient adsorption on the matrix soil surfaces. Ammonium (NH4+) and nitrate (NO3−) adsorption by a Plinthic Acrisol from Lampung, Indonesia was studied in column experiments. The peak of the H218O breakthrough occurred at 1 pore volume, whereas the median pore volumes for NH4+and NO3−ranged from 6.4 to 6.9 and 1.1 to 1.6, respectively. The adsorption coefficients (Kain cm3g–1) measured were 1.81, 1.51, 1.64 and 1.47 for NH4+and 0.03, 0.09, 0.10 and 0.17 for NO3−, respectively, in the 0–0.2, 0.2–0.4, 0.4–0.6 and 0.6–0.8 m soil depth layers. The NH4+and NO3−adsorption coefficients derived from this study were put in to the Water, Nutrient and Light Capture in Agroforestry Systems (WaNuLCAS) model to evaluate their effect on leaching in the context of several cropping systems in the humid tropics. The resulting simulations indicate that the inherent ‘safety‐net’ (retardation mechanism) of a shallow (0.8–1 m) Plinthic Acrisol can reduce the leaching of mineral N by between 5 and 33% (or up to 2.1 g m−2), mainly due to the NH4+retardation factor, and that the effectiveness in reducing N leaching increases with increasing depth. However, the inherent ‘safety‐net’ is useful only if deep‐rooted plants can recover the N subsequently.