bluuebunny/crossref_metadata_2025_split huggingface dataset:
Short‐term cortisol infusion in the brachial artery, with and without inhibiting 11β‐hydroxysteroid dehydrogenase, does not alter forearm vascular resistance in normotensive and hypertensive subjects
Authors: Van Uum S. H. M. , Hermus A. R. M. M. , Sweep C. G. J. , Walker B. R. , Ross H. A. , De Leeuw P. W. , Lenders J. W. M. 
Published: March 2003

AbstractBackground Vascular tone is increased in primary hypertension, and glucocorticoids affect vascular tone. Local cortisol availability is modulated by activity of 11β‐hydroxysteroid dehydrogenase (11β‐HSD). As this activity may be decreased in patients with primary hypertension, vascular sensitivity to cortisol may be increased in these patients. We studied the acute effect of cortisol on forearm vascular resistance (FVR) by infusing cortisol directly into the brachial artery, both with and without inhibition of 11β‐HSD, in normotensive and hypertensive subjects.Design Twenty normotensive volunteers and 20 patients with primary hypertension participated in the study. After a 10‐min infusion of vehicle (glucose 5%), cortisol was infused into the brachial artery in three stepwise increasing doses (3·5, 10·5 and 35 µg per 100 mL of forearm volume), each for 10 min. Next, the participants received placebo or 500 mg glycyrrhetinic acid (GA) orally, and 150 min later the same infusion schedule was repeated. Forearm vascular resistance was measured during the last 5 min of the infused vehicle and of each dose. Arterial and forearm venous plasma samples for measurement of cortisol and cortisone were taken at the end of the infusions of glucose 5% and the highest cortisol dose.Results In both normotensive and hypertensive subjects, neither the infusion of cortisol nor the administration of GA changed FVR. Also 2 h after the cortisol infusion there remained no change in FVR in both the normotensive and hypertensive groups who received placebo. Following the infusion of the highest cortisol dose, total plasma cortisone levels in the venous plasma were decreased compared with levels in the arterial plasma (36 ± 3 and 49 ± 4 nmol L−1, respectively, P < 0·05). The protein‐bound venous cortisone was 37·1 ± 4·8 nmol L−1 during the vehicle compared with 23·9 ± 3·7 nmol L−1 during the cortisol infusion (P < 0·01), whereas the free cortisone level was not altered by the cortisol infusion.Conclusions In both normotensive and hypertensive subjects, high‐dose cortisol infusion both with and without 11β‐HSD inhibition did not change FVR either immediately or after 2 h. We could not demonstrate in vivo 11β‐HSD activity in the forearm vascular tissues. When binding of cortisone to CBG is changed, e.g. during cortisol infusion, arterio‐venous changes in cortisone cannot reliably be used to assess (alterations in) local 11β‐HSD activity.
Transferrin toxin but not transferrin receptor immunotoxin is influenced by free transferrin and iron saturation
Authors: Gosselaar P. H. , Van‐Dijk A. J. G. , De‐Gast G. C. , Polito L. , Bolognesi A. , Vooijs W. C. , Verheul A. F. M. , Krouwer H. G. J. , Marx J. J. M. 
Published: March 2003

AbstractBackground  Cytotoxic agents can be targeted successfully to cancer cells. The efficacy of such novel and potent anticancer strategies may be influenced by variables of iron metabolism.Methods  The in vitro cytotoxicity against glioma cells of transferrin (Tf)‐based targeted toxins was compared with that of α‐transferrin receptor (TfR)‐immunotoxin.Results  Of four Tf‐based targeted toxins, Tf‐gelonin, Tf‐pokeweed antiviral protein, Tf‐momordin and Tf‐saporin, inhibitory concentration 50% values against glioma‐derived cell lines HS683 and U251, ranged from [4·8 ± 1·5] × 10−10 m for Tf‐saporin to [26·9 ± 15·3] × 10−10 m for Tf‐gelonin in [3H]‐leucine incorporation assays. Tf‐saporin and α‐TfR‐saporin‐immunotoxin had similar efficacy, even in the more quantitative clonogenic assay (4–5 log kill with 1 × 10−9 m) using the myeloma cell line RPMI 8226 and glioma cell line U251. However, on RPMI 8226, the efficacy of Tf‐saporin 1 × 10−9 m was reduced by 90% in the presence of 150 µg mL−1 (=20% of normal plasma value) competing diferric transferrin, whereas the efficacy of the corresponding immunotoxin was affected only marginally. In addition, the efficacy of Tf‐based conjugates will depend on their iron saturation state. Iron desaturation of Tf‐saporin was demonstrated by [59Fe]‐labelling, subsequent CM‐Sepharose chromatography and SDS‐PAGE. Desaturation led to virtually complete loss of affinity for the transferrin receptor, as determined by flow cytometry, which could be largely restored upon resaturation.Conclusion  Transferrin‐based toxin conjugates are strongly influenced by the presence of free transferrin and the iron saturation state. The corresponding α‐transferrin receptor‐immunotoxin does not show these disadvantages, has similar efficacy and should be preferred for further experiments.
Frequencies of platelet‐specific alloantigen systems 1–5 in three distinct ethnic groups in Brazil
Authors: Castro V. , Origa A. F. , Annichino‐Bizzacchi J. M. , Soares M. , Menezes R. C. , Gonçalves M. S. , Costa F. F. , Arruda V. R. 
Published: March 2003

AbstractThe human platelet antigen (HPA) systems are related to immune platelet disorders as well as to the development of occlusive vascular disease. Several distinct biallelic HPA systems are known, and a heterogeneous distribution of HPA alleles has been described among distinct ethnic groups. In this study we genotyped 320 carefully selected individuals from three distinct ethnic groups in Brazil (Caucasians, Blacks and Amazonian Indians) for the HPA‐1, ‐2, ‐3, ‐4 and ‐5 systems. A similar prevalence for all HPA alleles was found in Brazilians of Caucasian and Black descent. These data contrast with those reported for similar ethnic groups in other countries. Among the Amazonian Indians, no b allele of the HPA‐1, ‐4 and ‐5 systems was identified. The data presented here could be useful in the diagnosis of alloimmune platelet disease, in genetic counselling and in the development of screening programmes for HPA‐related diseases.
Polymorphism of LMP2, TAP1, LMP7 and TAP2 in Brazilian Amerindians and Caucasoids: implications for the evolution of allelic and haplotypic diversity
Authors: Rueda Faucz F. , Macagnan Probst C. , Petzl‐Erler M. L. 
Published: March 2003

AbstractIn the class II region of the major histocompatibility complex (MHC), four genes implicated in processing of MHC class I‐presented antigens have been described. Two of these (TAP1 and TAP2) code for endoplasmic reticulum membrane transporter proteins and the other two (LMP2 and LMP7) for proteasome subunits. These genes are polymorphic, although much less so than classical MHC class I and II genes. There is controversy concerning the possible functional implications of this variation. Population genetics is one of the means of investigating the evolutionary and functional significance of genetic polymorphisms; however, few populations have been analysed with respect to TAP and LMP diversity. We present here the polymorphism of TAP1, TAP2, LMP2 and LMP7 genes in the Kaingang and Guarani Amerindian tribes, and in the Caucasoid population of the Brazilian State of Paraná. Allele frequencies found in the Caucasoids were close to those described for similar populations. Amerindians had a somewhat more restricted polymorphism, and allele and haplotype frequencies differed greatly between the two tribes. Overall linkage disequilibrium (LD) between the four genes was low in the Caucasoids, but high in the Amerindians, for which significant LD was seen for all informative pairs of loci. Comparing results of this and previous studies we observed that, whenever significant LD occurs in non‐Amerindians, it tends to be similar in the different ethnic groups. While this might be interpreted as evidence of co‐evolution of genes in the TAP‐LMP region, the high haplotypic diversity in all populations and low LD in non‐Amerindians indicate absence of co‐evolution of the different genes. Distributions of allele and genotype frequencies are consistent with the hypothesis of selective neutrality. We conclude that genetic polymorphism of the human TAP and LMP genes and haplotypes is of little, if any, functional significance.
Identification of further DLA‐DRB1 and DQA1 alleles in the dog
Authors: Kennedy Lorna J. , Hall Laurence S. , Carter Stuart D. , Barnes Annette , Bell Susan , Bennett David , Ollier Bill , Thomson Wendy 
Published: March 2003

AbstractThree novel DLA‐DRB1 alleles and one novel DQA1 allele have been identified in a panel of 367 dogs. These were suggested by unusual reaction patterns found in sequence specific oligonucleotide probing (SSOP) data. Four new alleles were confirmed using DNA cloning and sequencing.
Iron‐overload and genotypic expression of HFE mutations H63D/C282Y and transferrin receptor Hin6I and BanI polymorphism in German patients with hereditary haemochromatosis
Authors: Gottschalk R. , Seidl C. , Schilling S. , Braner A. , Seifried E. , Hoelzer D. , Kaltwasser J. P. 
Published: March 2003

AbstractGene variations of HFE, a HLA‐class I like molecule, are highly associated with hereditary haemochromatosis (HH). Functional as well as molecular studies of the HFE protein have indicated that the molecule is involved in iron metabolism and that the HFE gene variations observed among HH patients affect its interaction with the transferrin receptor (TfR). In the present study, we have therefore analysed the relationship between the HFE gene variants, C282Y and H63D, and body iron status among 85 German HH patients. In addition, two TfR gene polymorphism, TfR‐Hin6I and TfR‐BanI, were typed that have been reported to define ethnically distinct haplotypes. As controls we used 251/159 healthy German blood donors. Seventy‐eight (92%) patients were C292Y homozygous, the H63D mutation was present in five (6%) patients with none of the patients being H63D homozygous. Serum transferrin, transferrin saturation and liver iron content were determined prior to therapeutic intervention. Among C282Y homozygous patients serum ferritin levels (2294 ± 3174 vs. 463 ± 224 µg L−1, P < 0.0001) and transferrin saturation (86 ± 18% vs. 62 ± 25%, P = 0.048) were elevated significantly compared with C282Y and/or H63D heterozygous patients. In addition, the liver iron content (291 ± 165 vs. 138 ± 95 µmol g−1, P = 0.028) and liver iron index (6.4 ± 2.8 vs. 3.2 ± 2.3, P = 0.019) were increased among C282Y homozygotes compared with C282Y heterozygotes. In contrast, no difference was observed between patients and controls regarding the distribution of TfR‐Hin6I and TfR‐BanI alleles. These data indicate that the iron intake is higher among C282Y homozygous patients compared with C282Y heterozygous or C282Y/H63D compound heterozygous individuals and supports the functional role of the HFE protein in iron metabolism whereas the TfR gene variants seem to have no influence on iron uptake.
Allele frequencies of polymorphisms of the tumour necrosis factor‐α, interleukin‐10, interferon‐γ and interleukin‐2 genes in a North European Caucasoid group from the UK
Authors: Reynard M. P. , Turner D. , Navarrete C. V. 
Published: March 2003

AbstractCytokine gene polymorphisms affecting cytokine production may influence rejection and graft‐versus‐host disease following solid organ and haemopoietic stem cell (HSC) transplantation, respectively. Polymorphisms in the regulatory regions of several cytokine genes have been described; for example, tumour necrosis factor‐α (TNF‐α) has a G/A substitution at position −308, interleukin‐2 (IL‐2) has a T/G substitution at position −330 and interleukin‐10 (IL‐10) has substitutions at positions −1082(G/A), −819(C/T) and −592(C/A). Microsatellites associated with cytokine production have been detected in the first intron of the IFN‐γ gene and flanking the TNF‐α gene. In this study, we have genotyped a single panel of healthy Northern European Caucasoids living in the south‐east of England for the above‐mentioned polymorphisms and compared the results to those published for other populations. A PCR method using sequence‐specific primers (SSP) was developed for genotyping the IL‐2 polymorphism, and the ABI PRISM™ 310 genetic analyser was used to detect the TNF‐α and IFN‐γ microsatellites. The allele frequencies of all the studied polymorphisms were consistent with those reported for other UK Caucasoid populations, but differences were observed when compared to other Oriental, African and Caucasoid groups. If these cytokine polymorphisms prove to have functional consequences, then any differences across population groups may have significant clinical relevance in disease and in the outcome of solid organ and HSC transplantation.
TCRBV3S1 and TCRBV18 gene segment polymorphisms in Brazilian Caucasoid and Black populations
Authors: Dresch C. , Nardi N. B. , Chies J. A. B. 
Published: March 2003

SummaryThe T‐cell receptor (TCR) repertoire plays an important role in shaping specific immune responses. Genetic polymorphisms at the TCR locus, in both constant and variable regions, seem to represent an important mechanism for generating inter‐individual and inter‐population differences. Considering the scarcity of immune parameters characterized for normal human populations, we decided to determine the frequency of two TCRBV polymorphisms (located in the TCRBV3S1 and TCRBV18 gene segments) in two ethnically distinct groups of the general Brazilian population. Both polymorphisms are related to the expression of these segments at the T‐cell surface and can consequently modulate the T‐cell repertoire, potentially modifying the capacity of a given individual to develop an immune response. These DNA polymorphisms were analysed in material obtained from adult, normal South‐American Caucasoid and Black individuals. A total of 139 individuals were analysed for the TCRBV3S1 and 141 for the TCRBV18 gene segment polymorphisms. The data indicated statistically significant differences in allelic frequencies for the two ethnic groups analysed, suggesting that any correlation between TCR usage or T‐cell repertoire and development of a given disease should take in account the ethnic origin of the population studied.
Identification of a new isoform of human IL‐12 p35 mRNA
Authors: Johansson U. , Cooke S. P. , Londei M. 
Published: March 2003

SummaryThis study has identified an alternate mRNA isoform of the human interleukin‐12 p35 gene differing from normal p35 transcripts by the deletion of exon 3. Exon 3‐lacking p35 mRNA was produced by both dendritic cells and Epstein‐Barr virus‐transformed B cells and was detected only when transcription of normal p35 mRNA was abundant.
Associations of HLA class II alleles with pulmonary tuberculosis in Thais
Authors: Vejbaesya S. , Chierakul N. , Luangtrakool K. , Srinak D. , Stephens H. A. F. 
Published: March 2003

SummaryTuberculosis is an important infectious disease in Thailand. Susceptibility to tuberculosis is influenced not only by the environment but also by host genetic factors. In this study, we investigated HLA alleles in 82 patients with tuberculosis from Bangkok and in 160 normal controls. HLA‐DRB1, DQA1 and DQB1 genotyping was performed by the PCR‐SSO method. The frequency of HLA‐DQB1*0502 was increased in tuberculosis patients compared to the normal controls (P = 0.01, OR = 2.06). In contrast, the frequencies of DQA1*0601 and DQB1*0301 were decreased in tuberculosis patients compared to the controls (P = 0.02 and P = 0.01, respect­ively). Our results suggest that HLA‐DQB1*0502 may be involved in the development of pulmonary tuberculosis, whereas HLA‐DQA1*0601 and DQB1*0301 may be associated with protection against tuberculosis.
Determination of free Al3+ in soil solutions by capillary electrophoresis
Authors: Göttlein A. 
Published: March 2003

SummaryColorimetric and ion exchange methods are commonly used to distinguish and measure Al species in natural waters. Unfortunately they also include weakly complexed Al species in their ‘reactive' or ‘labile' Al fractions and thus are of limited value for the estimation of free Al3+. Capillary electrophoresis (CE) has the potential for direct measurement of Al3+, and its performance has been verified experimentally. The method also detected the stable and positively charged AlOx+ complex formed with oxalic acid. It was compared with a colorimetric and an ion exchange method by analysing artificial solutions containing low molecular weight organic acids as well as soil extracts and seepage waters and was found to be the only method closely matching the theoretically calculated values of free Al3+. In samples from the upper soil horizons of an acid forest soil less than 14% of total Al was present as free Al3+, whereas the colorimetric method found more than 65%, and the ion exchange method more than 80% of total Al in a ‘reactive' or ‘labile' form. The latter methods thus would seriously overestimate Al toxicity, whereas using CE Al toxicity is likely to be only slightly underestimated.
Fixation of radiocaesium in an acid brown forest soil
Authors: Maes E. , Delvaux B. , Thiry Y. 
Published: March 2003

SummaryThe OAh and Ah horizons of acid brown and podzolic forest soils are reported to fix more radiocaesium than the mineral B horizons beneath them. We determined the respective influence of organic matter and clay minerals on the magnitude of Cs+ retention in a strongly acid brown forest soil in Belgium. The soil contained mica throughout the profile. Vermiculite was identified in the OAh and Ah horizons, and hydroxy interlayered vermiculite (HIV) in the Bw horizon. The OAh and Ah clay fraction retained much more Cs+ than the Bw horizon. The extraction of Al interlayers by Na‐citrate resulted in a marked increase in Cs+ fixation in the Bw clays as well as the collapse of the vermiculitic layers after K+ saturation. Organic matter had a strong but indirect effect on Cs+ fixation. In the Bw horizon, acid weathering of layer silicates releases free Al and produces HIV minerals in which Al polymers block the access of radiocaesium onto Cs+‐specific sites. In OAh and Ah horizons, free Al is complexed by organic acids. Consequently, the interlayer specific sites remain accessible for Cs+ fixation.
Morphological and genetic relations between siderite, calcite and goethite in a Low Moor Peat from southern Germany
Authors: McMILLAN  , SCHWERTMANN  
Published: March 2003

Siderite, calcite and goethite occur in a Low Moor Peat near Freising, southern Germany. Siderite is present mainly as microcrystalline ovoids which have a lamellar structure and are less than 5 μm long. Selected area electron diffraction and X‐ray diffraction data suggest a crystal size less than that of the ovoids, probably as small as 20–50 nm. Siderite occurs interstitially between plant materials, predominantly of the genus Equisetum. Calcite, which is subordinate to siderite, occurs as pseudomorphs of plant cells. This suggests an earlier crystallization for calcite predating that of the siderite.The distribution of mineral morphologies and pH and Eh data suggest that siderite weathers by oxidation to goethite under mildly alkaline conditions, despite the probable production of protons. This process initially involves a pseudomorphism of the siderite ovoids by goethite. However, the goethite, comprising poorly acicular crystals with a mean coherence length of 11 nm normal to the 111 plane, eventually develops into a massive fabric.Calcite occurs with goethite in oxidized samples in the same location as in the unoxidized samples, but in decreased amount. Thus, calcite dissolution may act as a buffer to siderite oxidation.
Nitrous oxide production by denitrification and nitrification in temperate forest, grassland and agricultural soils
Authors: AMBUS P. 
Published: March 2003

SummaryNitrous oxide is produced in soils by biological denitrification and nitrification. To improve the fundamental understanding of the processes leading to N2O fluxes from soils, the production of N2O from denitrification and nitrification in spruce forest, beech forest, riparian grassland, coastal grassland and an agricultural field were studied. Samples were taken at a high and a low position along a topographic gradient in each site in the spring and autumn when the largest N2O fluxes were expected. They were incubated after being amended with N, and C2H2 was used as biological inhibitor to distinguish nitrification and denitrification.The N2O production in the low landscape position varied between 32 and 121 ng N cm−3 h−1 in the riparian grassland. 9 and 26 ng N cm−3 h−1 in the coastal grassland, and 135 and 195 ng N cm−3 h−1 in the agricultural field which was 10–100 times more than in the high positions where rates ranged between 3 and 5 ng N cm−3 h−1, 0.3 and 0.4 ng N cm−3 h−1, and 7 and 10 ng N cm−3 h−1, respectively. These differences almost certainly arose because the soil in the low positions was wetter and contained more organic matter. In the two forests N2O production was less than 1 ng N cm−3 h−1, strongly inhibited by O2, and not influenced by landscape position. Nitrification contributed to more than 60% of total N2O production in the riparian grassland. In the agricultural field nitrification produced 13–74% of the total N2O in the low position, and 10–88% in the high position. Denitrification was the dominant source of N2O in the coastal grassland except at the low position in the autumn where nitrification produced 60% of the total N2O. In the two forests where the soil had small nitrification potentials denitrification was the only source of N2O. In the other sites nitrification and denitrification potentials were large and of identical magnitude. The results emphasize the need to separate nitrification and denitrification at the process level and to recognize topography at the field scale when modelling N2O effluxes from soil.
Composition of soil organic matter and its water‐soluble fraction under young vegetation on drift sand, central Netherlands
Authors: NIEROP K. G. J. , BUURMAN P. 
Published: March 2003

SummaryPodzols tend to form on drift sands in The Netherlands given sufficient time. Differences in organic matter (OM) composition relate to vegetation succession on drift sand that evolves eventually into a micropodzol. We examined the relation between the water‐soluble organic matter (WSOM) and the total OM composition in the Ah horizons of the first vegetation stages, under grass (Corynephorus canescens), moss (Polytrichum piliferum), heather (Calluna vulgaris) and pine (Pinus sylvestris), as determined by pyrolysis‐gas chromatography/mass spectrometry (Py‐GC/MS) and analysis of polysaccharides after acid hydrolysis. Polysacharides dominate the OM in the Ah horizons under grass and moss. Lignin and aliphatic compounds are minor compounds in these profiles, but are more important under heather and pine. The Py‐GC traces of the WSOM under grass and moss contain abundant products derived from polysaccharides. The water‐soluble fraction is enriched in phenolic and aliphatic compounds in comparison with their contents in pyrolysates of the total OM. In the WSOM fractions under heather and pine, phenols dominate the pyrolysates, whereas lignin‐derived methoxyphenols are rare. Remarkably large amounts of alkenes and alkanes are present in the pyrolysates of these water‐soluble fractions, most probably derived from aliphatic biopolymers. Their presence in water might be explained through the formation of colloids, which are stabilized by micelle‐like arrangements.