bluuebunny/crossref_metadata_2025_split huggingface dataset:
Oxidative status and malondialdehyde in β‐thalassaemia patients
Authors: Cighetti G. , Duca L. , Bortone L. , Sala S. , Nava I. , Fiorelli G. , Cappellini M. D. 
Published: March 2003

AbstractBackground In β‐thalassaemia syndromes, decreased or impaired biosynthesis of β‐globin leads to accumulation of unpaired α‐globin chains. Moreover, the iron overload in β‐thalassaemia patients generates oxygen‐free radicals and peroxidative tissue injury. The aim of this study was to detect and correlate iron overload parameters with the oxidative stress and the antioxidant capability in β‐thalassaemia patients.Design Serum iron, transferrin saturation, serum ferritin, nontransferrin‐bound iron (NTBI), levels of serum free and total (free + bound) malondialdehyde (MDA) and total peroxyl radical‐trapping antioxidant parameter (TRAP) were evaluated in 21 regularly transfused β‐thalassaemia major (TM) patients, 13 untransfused β‐thalassaemia intermedia (TI) patients and 17 healthy controls. Blood from the TM patients was drawn 48 h after the last desferoxamine (20–40 mg kg−1) infusion and just before transfusion.Results Free and total MDA and NTBI levels were higher in the TM patients than in the TI. In the TM patients the free MDA levels correlated positively with serum iron (r = +0·3, P = 0·0006), whereas the total MDA correlated positively with NTBI (r = +0·45, P = 0·037). However, a negative correlation was observed between TRAP and NTBI (r = −0·4, P = 0·0006). In the TI patients there was no significant correlation between free or total MDA and TRAP or NTBI.Conclusions Our results confirm the peroxidative status generated by iron overload in thalassaemia patients and highlight the rapid formation of marked amounts of free MDA despite the chelation therapy in TM patients.
Effects of age on the cardiac and vascular limbs of the arterial baroreflex
Authors: Brown C. M. , Hecht M. J. , Weih A. , Neundörfer B. , Hilz M. J. 
Published: March 2003

AbstractBackgroundHealthy ageing has several effects on the autonomic control of the circulation. Several studies have shown that baroreflex‐mediated vagal control of the heart deteriorates with age, but so far there is little information regarding the effect of ageing on sympathetically mediated baroreflex responses. The aim of this study was to assess the effects of ageing on baroreflex control of the heart and blood vessels.Materials and MethodsIn 40 healthy volunteers, aged 20–87 years, we applied oscillatory neck suction at 0·1 Hz to assess the sympathetic modulation of the heart and blood vessels and at 0·2 Hz to assess the effect of parasympathetic stimulation on the heart. Breathing was maintained at 0·25 Hz. Blood pressure, electrocardiographic RR intervals and respiration were recorded continuously. Spectral analysis was used to evaluate the magnitude of the low‐frequency (0·03–0·14 Hz) and high‐frequency (0·15–0·50 Hz) oscillations in the RR interval and blood pressure. Responses to neck suction were assessed as the change in power of the RR interval and blood pressure fluctuations at the stimulation frequency from baseline values.ResultsResting low‐ and high‐frequency powers of the RR interval decreased significantly with age (P < 0·01). However, the low‐frequency power of systolic blood pressure did not correlate with age. Spontaneous baroreflex sensitivity (alpha‐index) showed a significant inverse correlation with age (r = −0·46,P < 0·05). Responses of the RR interval and systolic blood pressure to 0·1 Hz neck suction stimulation were not related to age, however, the RR interval response to 0·2 Hz neck suction declined significantly with age (r = −0·61,P < 0·01).ConclusionsThese results confirm an age‐related decrease in cardiovagal baroreflex responses. However, sympathetically mediated baroreflex control of the blood vessels is preserved with age.
Vitamin D receptor gene polymorphism BsmI is not associated with the prevalence and severity of CAD in a large‐scale angiographic cohort of 3441 patients
Authors: Ortlepp J. R. , Von Korff A. , Hanrath P. , Zerres K. , Hoffmann R. 
Published: March 2003

AbstractBackground Recent studies found a relationship between Vitamin D and atherosclerosis. A common genetic polymorphism of the Vitamin D receptor (VDR) has been associated with coronary artery disease (CAD) in small study populations. To assess its influence on the prevalence and severity of CAD we studied a large‐scale population.Methods A total of 3441 consecutive patients were referred for diagnostic coronary angiography. The BsmI Vitamin D receptor polymorphism was analyzed by polymerase chain reaction. Angiography was used to define phenotypes with clear coronary arteries (n = 775), coronary sclerosis (diameter stenosis < 50%; n = 579), CAD (diameter stenosis > 50% in at least one vessel; n = 1524). Patients with CAD at a young age (females aged less than 65 years, males aged less than 55 years; n = 563) were specially defined as premature CAD. The risk profile of traditional cardiovascular risk factors was obtained for every patient.Results The genotype frequencies of the VDR BsmI polymorphism did not differ between all four phenotypes (P = 0·756). The allele frequencies for the B allele were 0·43 vs. 0·44 vs. 0·42 vs. 0·45 in the four phenotypic groups (P = 0·827). All traditional cardiovascular risk factors (hypercholesterolaemia, smoking, hypertension, diabetes mellitus, severe obesity, male gender) were significantly (P < 0·001) associated with the angiographic phenotype.Conclusions The VDR gene variant BsmI was not associated with prevalence and severity of CAD in a large‐scale cohort phenotyped by angiography.
Identifying the links between obesity, insulin resistance and β‐cell function: potential role of adipocyte‐derived cytokines in the pathogenesis of type 2 diabetes
Authors: Greenberg A. S. , McDaniel M. L. 
Published: March 2003

AbstractA combination of insulin resistance and pancreatic β‐cell dysfunction underlies most cases of type 2 diabetes. While the interplay of these two impairments is believed to be important in the development and progression of type 2 diabetes, the mechanisms involved are unclear. A number of factors have been suggested as possibly linking insulin resistance and β‐cell dysfunction in the pathogenesis of type 2 diabetes mellitus. Pro‐inflammatory cytokines such as tumour necrosis factor‐α (TNF‐α) have deleterious effects on both glucose homeostasis and β‐cell function, and can disrupt insulin signalling pathways in both pancreatic β cells and liver and adipose tissue. The anti‐inflammatory activity of the thiazolidinedione anti‐diabetic agents is potentially beneficial, given the possible role of pro‐inflammatory cytokines in linking insulin resistance with β‐cell dysfunction.
Confirmation of a recombinant allele B*5603 and a hypothetical reciprocal hybrid
Authors: Lyou J.‐Y. , Yang K. L. , Lee A. , Lin P. Y. , Lee T. D. 
Published: March 2003

SummaryFrom its DNA sequence, B*5603 is thought to be a product of gene conversion. We present here serological evidence of such an event and further speculate on a possible reciprocal hybrid yet to be identified. In addition, we report the allelic frequency of B*5603 in the Taiwanese population and its association with A*1101, Cw*01 and DRB1*1201.
The CTLA4 +49 A/G dimorphism is not associated with type 1 diabetes in Czech children
Authors: Cinek O. , Dřevínek P. , Šumník Z. , Bendlová B. , Koloušková S. , Šnajderová M. , Vavřinec J. 
Published: March 2003

SummaryWe investigated the association of the CTLA4 +49 A/G dimorphism with type 1 diabetes in Czech children. Genotyping of 305 diabetic children and 289 controls by a novel PCR‐ARMS assay revealed no significant differences in the genotypic or allelic frequencies. This may be another piece of evidence against the +49 A/G transition as the aetiological polymorphism within the CTLA4 gene.
A recently described polymorphism in the CD28 gene on chromosome 2q33 is not associated with susceptibility to type 1 diabetes
Authors: Wood J. P. , Pani M. A. , Bieda K. , Meyer G. , Usadel K.‐H. , Badenhoop K. 
Published: March 2003

SummaryType 1 diabetes mellitus is an autoimmune disease with a strong genetic background. The CTLA4 gene region (IDDM12) has been implicated in genetic susceptibility to type 1 diabetes by genome scanning and both family‐ and population‐based analyses. As the genes encoding the costimulatory molecules CTLA4 and CD28, which compete for the receptor B7, reside close together on chromosome 2q33 and have high sequence homology, we investigated a recently described polymorphism in intron 3 of the CD28 gene and the CLTA4 codon 17 polymorphism in 176 patients with type 1 diabetes and 220 healthy controls. Whereas CTLA4 was found to be associated with type 1 diabetes, the frequency of the CD28 polymorphism did not differ between patients and controls, either in the entire sample or after stratification for CTLA4 genotype. Thus, the CD28 intron 3 polymorphism does not appear to be associated with susceptibility to type 1 diabetes.
Polymorphism in codons 10 and 25 of the transforming growth factor‐beta 1 (TGF‐β1) gene in patients with invasive squamous cell carcinoma of the uterine cervix
Authors: Stanczuk G. A. , Tswana S. A. , Bergstrom S. , Sibanda E. N. 
Published: March 2003

SummaryTransforming growth factor‐beta 1 (TGF‐β1) has a multifactorial role in the development of cervical cancer. It potently inhibits the growth of epithelial cells that harbour oncogenic human papilloma viruses (HPVs). TGF‐β1 also inhibits the expression of the early viral transforming regions E6 and E7, which appear to be the key oncoproteins. It has been suggested that squamous cell carcinomas are devoid of TGF‐β1, raising the possibility that elevated levels of this growth factor could protect against cervical cancer. It is also recognized that the production and levels of TGF‐β1 are genetically predetermined and individually variable. Two genetic polymorphisms in the DNA encoding the leader sequence of the TGF‐β1 gene have been described and shown to be associated with the production of high or low TGF‐β1 levels in vivo and in vitro. We hypothesized that the inheritance of these polymorphisms could influence the development of invasive cervical cancer. This hypothesis was investigated by studying polymorphism in codons 10 and 25 of the TGF‐β1 gene. We studied 97 patients with invasive cervical cancer and 73 healthy controls and found that the distributions of alleles T (Leu) and/or C (Pro) and alleles G (Arg) and/or C (Pro) in codons 10 and 25, respectively, were similar. There was no significant association between the alleles and the histological degree of cancer differentiation. It appears that the role of this growth factor in cervical oncogenesis is not related to the point mutations that we examined in codons 10 and 25 of the TGF‐β1 gene. We speculate that other factors, including additional polymorphisms of the TGF‐β1 gene, the status of TGF‐β1 receptors, the complex cytokine network, differential responsiveness of cells to the stimuli, and the status of the precancer/cancer genome, may play a role in development of invasive cervical cancer.
Further support for the association of CCR5 allelic variants with asthma susceptibility
Authors: McGinnis R. , Child F. , Clayton S. , Davies S. , Lenney W. , Illig T. , Wjst M. , Spurr N. , Debouck C. , Hajeer A. H. , Ollier W. E. R. , Strange R. , Fryer A. A. 
Published: March 2003

SummaryEnglish and German nuclear families containing multiple asthmatic children and asthmatic parents were analysed to retest a recently reported association between resistance to asthma and the Δ32 allele of chemokine receptor 5 (CCR5). Analysis of the families by the transmission‐disequilibrium test (TDT) revealed a non‐significant trend in the English families that provided marginal confirmation of the association (P < 0.125), but no similar trend was observed in the German families. Case–control comparison of Δ32 allele and genotype frequencies in asthmatic vs. non‐asthmatic parents revealed a significantly lower frequency of Δ32 in asthmatic English parents (P < 0.009) and a similar but non‐significant trend in German parents (P < 0.265). Taken together, the pattern of results provides confirmation for the previously observed Δ32–asthma association and indicates that susceptibility to asthma may be influenced by CCR5 or another gene in chromosomal region 3p21.
Soil friability: theory, measurement and the effects of management and organic carbon content
Authors: Watts C. W. , Dexter A. R. 
Published: March 2003

SummaryThe weakest link between particles or aggregates determines the strength of soil. We have re‐examined the theory and, as a result, have re‐defined friability, F, as the coefficient of variation of soil tensile strength. The formal relationship between the parameter 1/α of the weakest link theory of strength, which has previously been used as a measure of friability, and the newly defined measure, F, is described by a simple equation which has an accuracy of within 2% over the range of interest. The quantity F is used to show that friability reaches maximum at water contents around the lower plastic limit, that mechanical disturbance of wet soil by tillage reduces the friability, and that friability is strongly positively correlated with the organic carbon content of the soil. These results show the merit of measuring friability for determining the optimum water content for tillage, for quantifying the damage done by different tillage practices, and as a theoretically based index of soil physical quality.
Transfer of dissolved Al, Fe and Si in two Amazonian forest environments in Brazil
Authors: CORNU S. , LUCAS Y. , AMBROSI J. P. , DESJARDINS T. 
Published: March 2003

SummaryThe balance of Si, Fe and Al in the soil solution determines more or less the course of soil formation in the tropics. We have tried to improve understanding of the processes by studying fluxes of dissolved Si, Fe and Al from the atmosphere, through the canopy and the soil, and to the groundwater, in two distinct Amazonian ecosystems, one a typical rainforest, developed on a Ferralsol, the other a so‐called ‘Campinarana’ forest, developed on a Podzol. The Si, Fe and Al in the rain and the throughfall and the stemflow were measured throughout a year, and the leaching of Si, Fe and Al through the upper soil and at the groundwater level were estimated. The annual balance showed that stemflow inputs were negigible compared with the contributions from throughfall and rain. The inputs of Fe, Al and Si to the topsoil from the rain and from dust and biological release in the canopy were small but not negligible. These sources contributed more aluminium in the Campinarana than in the rainforest. The rainfall constituted the main input of dissolved Fe and Al to the topsoil in both ecosystems. The element balances in the soil horizons confirmed that the present functioning of the Ferralsol results in aluminization and desilicification. We also found that the elements are transported in micropore flow and on translocated particles, as well as in freely percolating water.
The loess soils of China as records of climatic change
Authors: KEMP R. A. , DERBYSHIRE E. 
Published: March 2003

SummaryThe sequence of palaeosols and intervening loess units in North China provides a sensitive, detailed record of global climatic changes over the last 2.5 million years. Although various depth functions of properties, notably magnetic susceptibility, have been successfully correlated with oxygen isotope records from the deep oceans, there is a need to improve our understanding of such proxy measures used to infer past climates. For instance, pedologists are well placed to address some of the uncertainties surrounding the origin of the enhanced magnetic susceptibility (MS) values in palaeosols, and the reconstruction of palaeoprecipitation patterns by application of MS climofunctions. There are few published field descriptions of the soils buried in the loess, and those available often fail to recognize their accretionary and polycyclic nature. Field and micromorphological techniques enable finely detailed reconstructions of the pedogenic and sedimentary signals held in both palaeosol and loess units. Micromorphology, in particular, has provided detailed environmental information on successive pedosedimentary developmental stages at several sites in the Loess Plateau of China. This approach re‐focuses attention on the local, climatically sensitive mechanisms that underpin the inferred global patterns of climate.
Ilmenite in soil forming from a Brazilian amphibolite
Authors: DORIGUETTO A. C. , GOULART A. T. , DE JESUS FILHO M. F. , FABRIS J. D. , SANTANA G. P. 
Published: March 2003

SummaryIlmenite‐rich samples were obtained by chemical extraction methods from materials collected from a soil developing on an amphibolite and from its altered parent rock. The soil ilmenite of this mantle was found to be inherited from the rock, but its composition varied significantly from one soil fraction to another and according to its mineralogical association. Unit cell parameters are smaller than those of pure ilmenite: the a‐dimension of the hexagonal structure varies from 0.5076 ± 0.0004 to 0.5083 ± 0.0007 nm. Mössbauer patterns at room temperature reveal that this mineral, which is most often associated with the iron‐rich spinel phase, actually corresponds to a member of the haematite–ilmenite series having the general formula xFeTiO3.(1‐x)Fe2O3, with 0.83 ≤x≤ 0.95. There is a correlation (r= 0.95) between x, the molar fraction of FeTiO3, and the a‐dimension of the unit cell.
Interaction between clay microstructure, decomposition of plant residues and humification
Authors: D'ACQUI L. P. , DANIELE E. , FORNASIER F. , RADAELLI L. , RISTORI G. G. 
Published: March 2003

SummaryWe have studied microstructural changes in montmorillonite and kaolinite, which were amended with organic debris (leaves of chestnut or beech), microbial inoculum and nutrients and subjected, for 30 days at 25°C, to alternate drying and wetting (D–W) or kept continuously moist at water‐holding capacity (WHC). The objective was to evalute the interactions between the decomposition of plant residues and clay microstructural organization in different pore–water regimes. The microstructure was studied by Hg porosimetry, N adsorption at 77 K, and scanning electron microscopy. Decomposition was assessed by measuring residual C and N, the amount of humified material, the relative contents of humic (HA) and fulvic (FA) acids, and their molecular weight distribution. The structural organization at the end of the experiments was different for the two clays, and new classes of pores were found as the result of the microbial metabolism. The decomposition was also significantly affected by clay type. Decomposition of the organic matter (OM) was rapid in the montmorillonite. The humified material occured mainly as low molecular weight FAs. By contrast, transformation was slow in kaolinite, leaving much residual C, and more of the humified material consisted of HAs. Alternate D–W had little effect on microstructure and decomposition. Samples that were kept moist and amended with chestnut leaves produced the greatest amount of humified substances. The dynamics of the decomposition was significantly affected by the nature of the leaves as indicated by the differences in residual C, humified material and C/N ratio. By contrast, changes in pore size distribution (PSD) were litle influenced by the type of organic debris.
Soil moisture monitoring at the field scale using automatic capacitance probes
Authors: CHANZY A. , CHADOEUF J. , GAUDU J. C. , MOHRATH D. , RICHARD G. , BRUCKLER L. 
Published: March 2003

SummaryThe capacitance probe is an attractive device for monitoring soil moisture automatically. However, its sphere of influence is rather small (a few cubic centimetres only). We have analysed the possibility of monitoring moisture at the field scale using only a few probes (≤3). We calibrated each probe by establishing a direct relation between the field average soil moisture θf and the signal given by the probe. As in earlier studies, we found that a linear relation is generally suitable. A classical statistical analysis was performed to assess the error of a single probe. When replicate probes were installed, we obtained replicate estimates of θf. We proposed an estimator θf that combines all replications optimally.Three experiments each lasting several months were carried out on bare tilled fields to evaluate the probe against gravimetric measurements. Our results show that the calibrations differ significantly from one probe to another. Once calibrated, the capacitance probe provided accurate soil moisture measurements (70% of the calibration relations had residual standard deviations < 0.02m3m−3), but it is advisable to have at least two replicate probes. Soil water storage was well estimated by combining four to seven probes to establish the moisture profile, despite the error induced by each probe. Moreover, the temporal variations in water storage were accurately measured by the probes. We found an error of 0.6 mm day−1 (standard deviation) in daily variation of the water storage, which partly involved the error made on the reference measurements (gravimetric method).
The effect of maize straw placement on mineralization of C and N in soil particle size fractions
Authors: Stemmer M. , Von Lützow M. , Kandeler E. , Pichlmayer F. , Gerzabek M. H. 
Published: March 2003

SummaryFundamental knowledge about the complex processes during the decomposition, mineralization and transfer of residue organic matter in soils is essential to assess risks of changes in agricultural practices. In a double tracer (13C, 15N) experiment the effect of maize straw on the mineralization dynamics and on the distribution of maize‐derived organic matter within particle size fractions was investigated. Maize straw (a C4 plant) labelled with 15N was added to soils (13.2 g dry matter kg–1 soil) which previously had grown only C3 plants, establishing two treatments: (i) soil mixed with maize straw (mixed), and (ii) soil with maize straw applied on the surface (surface). Samples were incubated in the laboratory at 14°C for 365 days. The size fractions (> 200 μm, 200–63 μm, 63–2 μm, 2–0.1 μm and < 0.1 μm), obtained after low‐energy sonication (0.2 kJ g–1), were separated by a combination of wet‐sieving and centrifuging. The mineralization of maize C was similar in the two treatments after one year. However, decomposition of maize particulate organic matter (predominantly in the fraction > 200 μm) was significantly greater in the mixed treatment, and more C derived from the maize was associated with silt‐ and clay‐sized particles. A two‐component model fitted to the data yielded a rapidly mineralizable C pool (about 20% of total C) and a slowly mineralizable pool (about 80%). Generally, the size of the rapidly mineralizable C pool was rather small because inorganic N was rapidly immobilized after the addition of maize. However, the different mean half‐lives of the C pools (rapidly decomposable mixed 0.035 years, and surface‐applied 0.085 years; slowly decomposable mixed 0.96 years, and surface‐applied 1.7 years) showed that mineralization was delayed when the straw was left on the surface. This seems to be because there is little contact between the soil microflora and plant residues. Evidently, the organic matter is more decomposed and protected within soil inorganic compounds when mixed into the soil than when applied on the soil surface, despite similar rates of mineralization.