bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reactive oxygen species induce RNA damage in human atherosclerosis
Authors: Martinet W. , De Meyer G. R. Y. , Herman A. G. , Kockx M. M. 
Published: May 2004

AbstractBackground  Reactive oxygen species (ROS)‐induced DNA damage has recently been identified in both human and experimental atherosclerosis. This study was undertaken to investigate whether RNA damage occurs in human atherosclerotic plaques and whether this could be related to oxidative stress.Materials and methods  The integrity of total RNA isolated from carotid endarterectomy specimens (n = 20) and nonatherosclerotic mammary arteries (n = 20) was analyzed using an Agilent 2100 Bioanalyser (Agilent Technologies, Palo Alto, CA). Oxidative modifications of RNA were detected by immunohistochemistry.Results  Eleven out of 20 atherosclerotic plaques showed a significant reduction of the 18S/28S rRNA peaks and a shift in the RNA electropherogram to shorter fragment sizes. In contrast, all mammary arteries showed good‐quality RNA with clear 18S and 28S rRNA peaks. Strong nuclear and cytoplasmic immunoreactivity for oxidative damage marker 7,8‐dihydro‐8‐oxo‐2′‐guanosine (8‐oxoG) could be detected in the entire plaque in smooth muscle cells (SMCs), macrophages and endothelial cells, but not in SMCs of adjacent normal media or in mammary arteries. Cytoplasmic 8‐oxoG staining in the plaque clearly diminished when tissue sections were pretreated with RNase A, suggesting oxidative base damage of RNA. In vitro treatment of total RNA with ROS‐releasing compounds induced RNA degradation.Conclusion  Both loss of RNA integrity and 8‐oxoG oxidative modifications were found in human atherosclerotic plaques. Because RNA damage may affect in vitro transcript quantification, RT‐PCR results must be interpreted cautiously if independent experimental validation (e.g. evaluation of RNA integrity) is lacking.
Basal and exercise‐induced sympathetic nervous activity and lipolysis in adipose tissue of patients with anorexia nervosa
Authors: Bartak V. , Vybiral S. , Papezova H. , Dostalova I. , Pacak K. , Nedvidkova J. 
Published: May 2004

AbstractBackground  The sympathetic nervous system plays an important role in the regulation of adipose tissue (AT) lipolysis, which is a key step in the metabolic processes leading to the decrease of fat mass. The present study was designed to determine in vivo basal and exercise‐stimulated lipolysis and concentrations of catecholamines, the major hormones controlling lipolysis, in subcutaneous abdominal AT in patients with anorexia nervosa (AN), characterized by self‐induced starvation and excessive exercises resulting in severe malnutrition and fat store loss. The results of local catecholamines and glycerol levels were compared with those in plasma in both experimental groups.Material and methods  An in vivo microdialysis technique was used for the assessment of norepinephrine, dihydroxyphenylalanine, dihydroxyphenylacetic acid and glycerol concentrations in subcutaneous AT of 10 women with AN (body mass index: 15·57 ± 0·55 kg m−2) and 10 age‐matched controls (body mass index: 21·56 ± 0·41 kg m−2). Both the AN patients and the control subjects underwent a 1·5 W kg−1 exercise test.Results  Basal AT norepinephrine concentrations were increased in the AN patients in comparison with the controls. Basal AT glycerol concentrations were similar in both groups. During exercise, a local increase in the AT norepinephrine and glycerol concentrations was observed in the AN patients only. In contrast to the controls, the basal AT dihydroxyphenylalanine and dihydroxyphenylacetic acid levels in the AN patients were high and remained unchanged during exercise. Basal and exercise‐stimulated plasma norepinephrine, dihydroxyphenylalanine, dihydroxyphenylacetic acid and glycerol levels were not different in the AN patients and healthy controls.Conclusion  Our study provides evidence of elevated baseline and exercise‐induced sympathetic nervous activity and exercise‐induced lipolysis in abdominal AT of AN patients.
Low‐grade systemic inflammation impairs arterial stiffness in newly diagnosed hypercholesterolaemia
Authors: Pirro M. , Schillaci G. , Savarese G. , Gemelli F. , Vaudo G. , Siepi D. , Bagaglia F. , Mannarino E. 
Published: May 2004

AbstractBackground  Excess of cardiovascular risk among patients with chronic inflammatory diseases has been attributed to increased arterial stiffness. Hypercholesterolaemia has been demonstrated to promote a low‐grade inflammatory status. The objective of the present study was to define, in hypercholesterolaemia, the influence of plasma lipids, low‐grade inflammation, and indices of adiposity on aortic pulse wave velocity, a measure of arterial stiffness and cardiovascular risk.Materials and methods  Anthropometric characteristics, plasma lipids, C‐reactive protein and aortic pulse wave velocity were measured in 85 subjects (60 patients with newly diagnosed never‐treated hypercholesterolaemia and 25 age‐ and sex‐matched normocholesterolaemic controls).Results  Plasma C‐reactive protein and aortic pulse wave velocity were significantly higher among hypercholesterolaemic patients than in controls (P < 0·05 for both). Aortic pulse wave velocity was associated with age (r = 0·24, P = 0·04), body mass index (r = 0·33, P = 0·006), waist (r = 0·42, P < 0·001) and hip (r = 0·32, P = 0·007) circumferences, as well as with systolic (r = 0·34, P = 0·003) and diastolic (r = 0·30, P = 0·01) blood pressures, plasma C‐reactive protein (r = 0·51, P < 0·001), total cholesterol (r = 0·45, P < 0·001), and low‐density lipoprotein cholesterol (r = 0·46, P < 0·001). In the multivariate analysis, waist circumference and C‐reactive protein levels predicted increased aortic stiffness, independently of traditional cardiovascular risk factors. The degree of independent association between cholesterol, systolic blood pressure and aortic stiffness increased when indices of adiposity and inflammation were excluded from the multivariate analysis. Comparable results were obtained when the analyses were restricted to hypercholesterolaemic patients.Conclusions  Low‐grade systemic inflammation and abdominal fat, more than traditional risk factors, are major determinants of reduced arterial distensibility in hypercholesterolaemia.
Increasing neutrophil F‐actin corrects CD11b exposure in Type 2 diabetes
Authors: Advani A. , Marshall S. M. , Thomas T. H. 
Published: May 2004

AbstractBackground  Leukocyte dysfunction contributes to the pathogenesis of diabetic vascular complications. Neutrophils adhere to the endothelium through the β2integrin CD11b/CD18. In Type 2 diabetes, neutrophil surface CD11b expression is increased and is associated with impaired actin polymerization. This study aimed to determine whether increasing neutrophil actin polymerization could correct the defect in CD11b exposure.Design  Neutrophil actin polymerization was stimulated with the tyrosine phosphatase inhibitor phenylarsine oxide (PAO), and cytoskeletal phosphotyrosine was monitored by immunoblotting Triton X‐100 insoluble fractions of cells. Neutrophil F‐actin was measured with phalloidin‐FITC staining, and surface CD11b expression was determined with anti‐CD11b‐PE before analysis with flow cytometry.Results  Phenylarsine oxide caused an increase in phosphotyrosine in neutrophils from both patients with Type 2 diabetes (DM) and controls (NC) (‐fold increase: NC, 1·43 ± 0·16; DM, 1·46 ± 0·10). The response to PAO in terms of phalloidin‐binding was impaired in neutrophils from patients [phalloidin‐FITC MFI area under the curve, NC 200 ± 5 (× 103), DM 124 ± 9 (× 103), P < 0·0001]. Phenylarsine oxide at concentrations < 10 µmol L−1 also caused loss of CD11b from neutrophil surfaces that was impaired in samples from patients [CD11b sites area under the curve NC 90 ± 6 (× 103), DM 121 ± 9 (× 103), P < 0·002]. However, in neutrophils from patients, incubation with PAO at a concentration of > 10 µmol L−1 caused a significant increase in intracellular F‐actin and CD11b down‐regulation equivalent to that observed in controls.Conclusion  In Type 2 diabetes, impaired neutrophil actin polymerization even in response to increasing cytoskeletal phophotyrosine suggests a downstream defect. Furthermore, increasing actin polymerization, above a minimum threshold level, corrects the defect in integrin exposure. Correction of the actin polymerization defect in Type 2 diabetes could improve the prognosis of diabetic vascular complications.
Natriuretic peptides as markers of preclinical cardiac disease in obesity
Authors: Grandi A. M. , Laurita E. , Selva E. , Piantanida E. , Imperiale D. , Giovanella L. , Guasti L. , Venco A. 
Published: May 2004

AbstractBackground  Aim of the study was to evaluate the role of atrial (ANP) and brain natriuretic peptides (BNP) as markers of preclinical cardiac disease in obesity.Methods  We selected 26 obese (BMI > 29 kg m−2) never‐treated hypertensives (24‐h BP > 140 and/or 90 mmHg), 26 obese normotensives (24‐h BP < 130/80 mmHg) and 25 lean (BMI 25 kg m−2) never‐treated hypertensives. Each subject underwent measurements of ANP and BNP plasma levels, 24‐h ambulatory blood pressure (BP) monitoring, digitized M‐mode and Doppler echocardiography.Results  Mean values of ANP and BNP were similar among the three groups. All the subjects had normal left ventricular (LV) systolic function. Within each group ANP levels were higher in patients with LV diastolic dysfunction than in patients with normal diastolic function, and BNP levels were higher in patients with LV hypertrophy and in patients with LV diastolic dysfunction. Within each group, ANP levels were inversely correlated with LV diastolic indices, whereas BNP levels were directly correlated with LV mass index and inversely correlated with LV diastolic indices. ANP and BNP levels were not correlated with other echocardiographic parameters, age, BMI or 24‐h BP values.Conclusion  In normotensive and hypertensive obese subjects the relationships of ANP and BNP levels with LV morpho‐functional characteristics follow the same trend as in lean hypertensives, with ANP mainly influenced by diastolic dysfunction and BNP influenced by both LV hypertrophy and LV diastolic dysfunction. Therefore ANP and BNP can be considered useful markers of preclinical cardiac disease in obesity.
Radioiodine therapy in hyperthyroidism: inverse correlation of pretherapeutic iodine uptake level and post‐therapeutic outcome
Authors: Walter M. A. , Christ‐Crain M. , Eckard B. , Schindler C. , Nitzsche E. U. , Müller‐Brand J. , Müller B. 
Published: May 2004

AbstractBackground  High iodine uptake levels are widely accepted as a condition for successful treatment with radioiodine (RAI). However, the existing data are controversial and the correlation of pretherapeutic RAI uptake level and outcome of RAI therapy has not yet been quantified. The aim of this study was to analyze the influence of RAI uptake on the outcome after RAI treatment and to estimate uptake‐dependent success rates.Materials and methods  We retrospectively analyzed 229 patients (m = 53, f = 176; age 64 ± 14 years) suffering from toxic adenoma, multinodular goitre or Graves’ disease, respectively. Clinical status and T3, fT4 and TSH levels were assessed 3, 6, 12 and 18 months after treatment. Successful treatment was defined as loss of hyperthyroidism 18 months after radioiodine therapy. Logistic regression was used to assess the relation between the maximum iodine uptake and the rate of success and hypothyroidism, respectively, after RAI treatment.Results  Overall, patients presented with pretherapeutic RAI uptake values between 17% and 100%. Eighteen months after RAI treatment, an euthyroid state was achieved in 136 patients (60%), hypothyroidism occurred in 47 patients (20%) and 46 patients (20%) remained hyperthyroid. The patients with the lowest pretherapeutic RAI uptakes showed the highest success rates. The overall success rate significantly decreased from 92% at low RAI uptakes to 57% at high uptakes (P = 0·002). This effect was found in the patients suffering from multinodular goitre as well as in the patients with Graves’ disease.Conclusion  In contrast to the current opinion, our results provide evidence that the pretherapeutic iodine uptake level and post‐therapeutic outcome are inversely correlated.
Seasonal changes in the stable isotope values of lake‐dwelling chironomid larvae in relation to feeding and life cycle variability
Authors: Grey Jonathan , Kelly Andrew , Ward Susan , Sommerwerk Nike , Jones Roger I. 
Published: May 2004

Summary1. We studied seasonal changes in the carbon and nitrogen stable isotope ratios of larval Chironomus anthracinus and C. plumosus from the profundal sediments of four contrasting lakes.2. Pronounced seasonal changes in both δ13C and δ15N values were evident in chironomid larvae of both species from two summer‐stratified, eutrophic lakes: Esthwaite Water and Wyresdale Park. Changes were most marked in the larvae of C. plumosus and in larvae from greater depths. In contrast, neither C. anthracinus in summer‐stratified but mesotrophic Schöhsee, nor C. plumosus in polymictic Großer Binnensee, showed marked seasonality in larval stable isotope ratios.3. The particularly strong 13C‐depletion of larvae from the stratified, eutrophic lakes is attributed to a significant contribution of methane‐derived carbon to their diets. Feeding by larvae on isotopically light methanotrophic bacteria appears to occur mainly when autumn overturn of the water column restores oxygenated conditions to the sediment surface. At this time both δ13C and δ15N values of larvae decreased sharply.4. Changes in the mean stable isotope ratio of the larval populations can also occur when larger, more isotopically light, larvae pupate and emigrate from the population to hatch as imagos. This effect can induce seasonal changes in larval isotope values even in lakes in which there is no evidence of a significant involvement of methane‐derived carbon in their diets. Variations in emergence patterns between species and between lakes may generate differences in the seasonal pattern of change in stable isotope ratios in larval populations.5. Our results emphasise the importance of adequate seasonal sampling if stable isotope ratios are to be used as biomarkers to study the role of key groups, such as chironomid larvae, in the trophic structure of lakes.
Do cyanobacteria dominate in eutrophic lakes because they fix atmospheric nitrogen?
Authors: Ferber L. R. , Levine S. N. , Lini A. , Livingston G. P. 
Published: May 2004

Summary1. The sources of nitrogen for phytoplankton were determined for a bloom‐prone lake as a means of assessing the hypothesis that cyanobacteria dominate in eutrophic lakes because of their ability to fix nitrogen when the nitrogen : phosphorous (N : P) supply ratio is low and nitrogen a limiting resource.2. Nitrogen fixation rates, estimated through acetylene reduction with 15N calibration, were compared with 15N‐tracer estimates of ammonium and nitrate uptake monthly during the ice‐free season of 1999. In addition, the natural N stable isotope composition of phytoplankton, nitrate and ammonium were measured biweekly and the contribution of N2 to the phytoplankton signature estimated with a mixing model.3. Although cyanobacteria made up 81–98% of phytoplankton biomass during summer and autumn, both assays suggested minimal N acquisition through fixation (<9% for the in‐situ incubations; <2% for stable isotope analysis). Phytoplankton acquired N primarily as ammonium (82–98%), and secondarily as nitrate (15–18% in spring and autumn, but <5% in summer). Heterocyst densities of <3 per 100 fixer cells confirmed low reliance on fixation.4. The lake showed symptoms of both light and nitrogen limitation. Cyanobacteria may have dominated by monopolizing benthic sources of ammonium, or by forming surface scums that shaded other algae.
Small reductions in forest cover weaken terrestrial‐aquatic linkages in headwater streams
Authors: England L. E. , Rosemond A. D. 
Published: May 2004

Summary1. We assessed the impacts of deforestation on the energy base of headwater food webs in seven headwater streams in the Upper Chattahoochee basin, GA, U.S.A where percentage forest in catchments ranged from 82 to 96%. We measured terrestrial organic matter standing crop and determined consumer (crayfish and insectivorous fish) dependence on terrestrial versus aquatic energy sources via gut content and stable isotope analyses.2. Standing crop of coarse particulate organic matter (CPOM) declined with deforestation at large scales (i.e. catchment deforestation and riparian deforestation at the entire stream network scale). Terrestrial plant matter, the dominant component of crayfish guts, declined in crayfish guts with reductions in CPOM standing crop and with deforestation.3. Crayfish and insectivorous fish δ13C showed enrichment trends with deforestation, indicating isotopic divergence from CPOM, the most 13C‐depleted basal resource, with reductions in catchment and riparian forest cover. Crayfish δ13C also exhibited enrichment with decreased instream CPOM standing crop.4. A concentration‐dependent mixing model was used to calculate the relative dependence of crayfish and fish on terrestrial versus aquatic basal resources. Results suggested that both allochthonous CPOM and autochthonous production were important basal resources. Consumer dependence on CPOM decreased with reductions in canopy cover.5. Our data suggest the importance of forest cover to headwater food webs at multiple scales, and that relatively low levels of riparian deforestation along headwater streams can lead to reductions in stream food web dependence on terrestrial subsidies.
Movement of plankton through lake‐stream systems
Authors: Walks D. J. , Cyr H. 
Published: May 2004

Summary1. River plankton are often assumed to come from upstream lakes, but the factors controlling the movement of plankton between lakes and rivers into outflow streams are unclear. We tested the possibility that the physical structure of the littoral zone near the lake outlet (depth, presence of macrophytes) and diurnal differences in plankton composition at the lake surface influence the movement of plankton from the lake into the stream and determine their persistence downstream.2. Zooplankton and phytoplankton biomass, community composition and mean body size were compared between two deep lakes without macrophytes at the lake edge and two shallow lakes with macrophytes at the lake edge. Samples were collected day and night on three dates, in the lake centre, in the littoral zone adjacent to the lake outlet, at the outlet and at two sites downstream in Algonquin Park, Ontario, Canada.3. The morphology of lake edges clearly affects the movement of lake zooplankton into outlet streams. Outlets draining deeper littoral zones had higher zooplankton biomass than shallow littoral outlets (P < 0.0001), but these differences disappeared within 50 m downstream of the lake. There was no difference in mean zooplankton body size among lake outlets or between littoral and outlet samples. However, shallow littoral zones were dominated by cyclopoid copepods and deeper littoral zones were dominated by Bosmina longirostris. In contrast, phytoplankton biomass entering the outlet was similar to that found within the lake and did not vary with lake outlet morphology. These effects were consistent across several sampling weeks and were not affected by surface zooplankton biomass changes associated with diurnal vertical migration in the lake centre.4. A comparison with published river zooplankton data suggests that zooplankton are rapidly eliminated from shallow outlet streams (≤1 m deep) but persist in most deeper outlet rivers (≥2 m deep). Because the depth of an outlet river determines downstream zooplankton community development, the contribution of lakes to river plankton communities may be influenced by the location of each lake within the drainage basin. These findings suggest that lake and outflow physical structure influences connection strength between spatially successive habitats.
Bacterioplankton production in freshwater Antarctic lakes
Authors: Laybourn‐Parry Johanna , Henshaw Tracey , Jones Davey J. , Quayle Wendy 
Published: May 2004

Summary1. Bacterioplankton production was measured in the water columns of two ultra‐oligotrophic, freshwater Antarctic lakes (Crooked Lake and Lake Druzhby) during an annual cycle. In both lakes bacterial production, measured by the incorporation of [3H] thymidine, continued in winter and showed a cycle over the year. The range of production was between 0 and 479 ng C L−1 h−1 in Crooked Lake and 0–354 ng L−1 h−1 in Lake Druzhby.2. Abundance and mean cell volume both varied, producing marked changes in biomass during the year, with highest biomass occurring in the winter and early spring. Biomass showed similar seasonal trends in both lakes.3. For most of the year inorganic forms of nitrogen and phosphorus were detectable in the water columns of the lakes and were unlikely to have limited bacterial production. Dissolved organic carbon (DOC) was below 3000 μg L−1. Dissolved amino acids and carbohydrates contributed 5–25% of the DOC pool in Crooked Lake and 5–64% in Lake Druzhby. Dissolved carbohydrates were consistently low, suggesting that this may have been the preferred carbon substrate for bacterioplankton.4. Aggregate associated bacteria had higher mean cell volume, abundances and production than freely suspended bacteria in Lake Druzhby, while in Crooked Lake aggregate associated bacteria consistently had higher mean cell volumes than free bacteria, but abundance and production were on occasion higher in free bacteria compared with aggregate associated communities.5. The data indicated that production is limited by continuous low temperatures and the limited availability of suitable DOC substrate. However, the bacterioplankton functions year round, responding to factors other than temperature.
Prey switching in four species of carnivorous stoneflies
Authors: Elliott J. M. 
Published: May 2004

Summary1. Previous studies compared the functional responses to their prey, and both intraspecific and interspecific interference, in mature larvae ofDinocras cephalotes,Perla bipunctata,Isoperla grammaticaandPerlodes microcephalus. The present study examines switching by larvae of the same species presented with different proportions of two contrasting prey types; larvae ofBaetis rhodaniandChironomussp. In each experiment, 200 prey were arranged in nine different combinations of the two prey types (20 : 180, 40 : 160, 60 : 140, 80 : 120, 100 : 100, 120 : 80, 140 : 60, 160 : 40, 180 : 20). Prey were replaced as they were eaten. A model predicted the functional response in the absence of switching and provided a null hypothesis against which any tendency for switching could be tested.2. No evidence for prey switching byDinocrasandPerlawas obtained, both species showing a slight preference forBaetisoverChironomus. Prey switching occurred inIsoperlaandPerlodes. As the relative abundance of one prey type increased in relation to the alternative, the proportion eaten of the former prey changed from less to more than expected from its availability, the relationship being described by an S‐shaped curve.IsoperlaandPerlodesswitched to a preference forBaetiswhen its percentage of the total available prey exceeded 57 and 42%, respectively. Equivalent values forChironomuswere 43 and 58% forIsoperlaandPerlodes, respectively. Switching was strongest inPerlodes.3. Non‐switching inDinocrasandPerlawas related to their feeding strategy, both species being more successful when using a non‐selective ambush strategy at dusk and dawn rather than a search strategy during the night. BothIsoperlaandPerlodesused a search strategy. The smallerIsoperlafed chiefly at dusk and dawn, and preferredChironomuslarvae, whereas most of the largerPerlodesfed continuously from dusk to dawn and preferredBaetislarvae.