bluuebunny/crossref_metadata_2025_split huggingface dataset:
A stable model of cirrhotic portal hypertension in the rat: thioacetamide revisited
Authors: Laleman W. , Elst I. Vander , Zeegers M. , Servaes R. , Libbrecht L. , Roskams T. , Fevery J. , Nevens F. 
Published: March 2006

AbstractBackground  Cirrhotic animal models are vital to investigate complications of chronic liver disease. We chronologically characterized the effect of thioacetamide, administrated orally and adapted weekly to weight changes, focusing on the optimal moment to obtain all typical features of portal hypertension and cirrhosis.Materials and methods  Male Wistar rats, 200–250 g, were intoxicated for 6, 12 or 18 weeks (n = 8 per group), respectively, and compared with age‐matched controls (n = 4 per group). An in‐situ perfusion model was used to evaluate intrahepatic resistance and endothelial function. Splanchnic blood flow and portosystemic shunting were assessed by a perivascular flow probe.Results  Rats intoxicated for 6 or 12 weeks had no mortality and histologically showed hepatitis and advanced fibrosis, respectively. At 18 weeks, mortality was 16% (on a total of 56 animals) and only at that moment all animals showed homogenous macronodular cirrhosis with signs of high‐grade hepatocellular dysplasia. Portal hypertension was present at 12 weeks (11 ± 0·4 vs. 5·9 ± 0·4 mmHg, P < 0·001), but was not associated with the hyperdynamic state until 18 weeks (12·1 ± 0·8 vs. 5·6 ± 0·5 mmHg, P < 0·001). At this latter time‐point, we also observed increased intrahepatic resistance associated with endothelial dysfunction, hyperresponsiveness to vasoconstrictors, splanchnic hyperaemia and portosystemic shunting. These alterations were associated with increased systemic levels of nitrate/nitrite and thromboxane A2.Conclusion  Thioacetamide, adapted to weekly weight changes, leads to a homogenous, reproducible model of cirrhosis in the rat in 18 weeks, which is associated with all the typical characteristics of portal hypertension, including endothelial dysfunction.
Interaction between cigarette, alcohol and betel nut use on esophageal cancer risk in Taiwan
Authors: Wu I. C. , Lu C. Y. , Kuo F. C. , Tsai S. M. , Lee K. W. , Kuo W. R. , Cheng Y. J. , Kao E. L. , Yang M. S. , Ko Y. C. 
Published: March 2006

AbstractObjective  In 2003 esophageal cancer was the sixth leading cause of death among men in Taiwan, but it is the fastest increasing (70%) alimentary tract cancer. The aim of this study was to investigate the impact of different habits of betel nut chewing on esophageal squamous cell carcinoma (SCC) and its interaction with cigarette use and alcohol consumption.Materials and methods  All 165 cases were pathologically proven esophageal SCC patients (all male, mean age = 56·0, range = 35–92 years) diagnosed by biopsy during gastroendoscopic examinations. The control group comprised 255 subjects (all male, mean age = 54·8, range = 40–92 years) selected from patients who had visited the Otolaryngology Outpatient or Inpatient Department of KMUH owing to a benign lesion over this field. All were interviewed to collect demographic and substance use information by a trained interviewer using a standardized questionnaire.Results  Smoking (aOR = 5·4, 95% CI = 2·4–12·9, PAR = 72%), alcoholic beverage drinking (aOR = 17·6, 95% CI = 9·3–35·2, PAR = 76%) and low education level are independent risk factors for esophageal cancer. Although betel nut chewers only had a borderline significant higher risk than nonchewers (aOR = 1·7; 95% CI = 0·8–3·1), those who chewed with a piece of betel inflorescence (aOR = 4·2, 95% CI = 1·4–16·0) and swallow betel‐quid juice (aOR = 3·3, 95% CI = 1·3–9·3) had a significant higher risk. Significant dose–response effects were found in daily quantity of drinking and smoking. There is a synergistic effect of these three substances on the development of esophageal cancer.Conclusion  Betel nut chewing plays a relevant role in the development of esophageal SCC but adds to the carcinogenetic effect of smoking and alcohol drinking. Direct mucosal contact of betel juice may contribute to its carcinogenesis
Effects of atorvastatin on high‐density lipoprotein apolipoprotein A‐I metabolism in dogs
Authors: Briand F. , Magot T. , Krempf M. , Nguyen P. , Ouguerram K. 
Published: March 2006

AbstractBackground  The mechanisms involved in the decline of high‐density lipoprotein (HDL) levels at a higher dose of atorvastatin have not yet been elucidated. We investigated the effects of atorvastatin on HDL‐apolipoprotein (apo) A‐I metabolism in dogs, a species lacking cholesteryl ester transfer protein activity.Materials and methods  Seven ovariectomized normolipidaemic female Beagle dogs underwent a primed constant infusion of [5,5,5‐2H3] leucine to determine HDL‐apo A‐I kinetics before and after atorvastatin treatment (5 mg kg−1 d−1 for 6 weeks). Plasma lipoprotein profiles, activity of HDL‐modifying enzymes involved in reverse cholesterol transport and hepatic scavenger receptor class B type I (SR‐BI) expression were also studied.Results  Atorvastatin treatment decreased HDL‐cholesterol levels (3·56 ± 0·24 vs. 2·64 ± 0·15 mmol L−1, P < 0·05). HDL‐triglycerides were not affected. HDL‐phospholipids levels were decreased (4·28 ± 0·13 vs. 3·29 ± 0·13 mmol L−1, P < 0·05), as well as phospholipids transfer protein (PLTP) activity (0·83 ± 0·05 vs. 0·60 ± 0·05 pmol µL−1 min−1, P < 0·05). Activity of lecithin: cholesterol acyl transferase (LCAT), hepatic lipase (HL) and SR‐BI expression did not change. HDL‐apo A‐I absolute production rate (APR) was higher after treatment (twofold, P < 0·05) as well as fractional catabolic rate (FCR) (threefold, P < 0·05). This resulted in lower HDL‐apo A‐I levels (2·36 ± 0·03 vs. 1·55 ± 0·04 g l−1, P < 0·05). Plasma lipoprotein profiles showed a decrease in large HDL1 levels, with lower apo A‐I and higher apo E levels in this subfraction.Conclusions  Although a high dose of atorvastatin up‐regulated HDL‐apo A‐I production, this drug also increased HDL‐apo A‐I FCR in dogs. This effect could be explained by a higher uptake of apo E‐enriched HDL1 by hepatic lipoprotein receptors.
Insulin secretion and sensitivity as determinants of HbA1c in type 2 diabetes
Authors: Monnier L. , Colette C. , Thuan J‐F. , Lapinski H. 
Published: March 2006

AbstractBackground  Defects in insulin secretion and sensitivity, two major determinants of glycaemic control, can occur and progress or not in parallel. The present study was designed to compare the respective roles of both determinants on HbA1c, in type 2 diabetic patients, according to whether or not residual beta‐cell function was stimulated with insulin secretagogues.Materials and methods  Insulin secretion and insulin sensitivity were both estimated using the homeostasis model assessment (HOMA). HbA1c, insulin sensitivity (HOMA2%S) and insulin secretion (HOMA2%B) were determined in 289 noninsulin‐using type 2 diabetic patients who were further divided into two groups according to treatment: metformin alone (group I, n = 57) or metformin and glyburide (group II, n = 232). The patients of both groups were further divided into three subsets in order to test the dependence of HbA1c on HOMA2%B and HOMA2%S.Results  In group I mean HbA1c were greater (8·4%) in patients with HOMA2%B < 50% than in the two subsets with HOMA2%B ≥ 50%: 7·2 and 6·8% (P = 0·0013). In group II mean values of stimulated‐insulin secretion (HOMA2%B) were lesser (40·7 and 30·1%) in the two subsets of patients with HbA1c ≥ 8% than in patients with HbA1c < 8%: 55·1% (P < 0·0001). By contrast, we found no differences in both groups with HOMA2%S. A stepwise multiple regression showed that HOMA2%B contributed to HbA1c more than HOMA2%S both in groups I (33·5% vs. 23·4%) and II (22·7% vs. 8%).Conclusions  Although the role of insulin sensitivity is not negligible, insulin secretion appears to be the major determinant of diabetic control in overt type 2 diabetic patients who are treated with metformin alone or with a two‐drug therapy combining metformin and glyburide.
Increased coronary sinus blood temperature: correlation with systemic inflammation
Authors: Toutouzas K. , Drakopoulou M. , Markou V. , Stougianos P. , Tsiamis E. , Tousoulis D. , Stefanadis C. 
Published: March 2006

AbstractBackground  Recent studies have shown that patients with single vessel coronary artery disease (CAD) suffering from acute coronary syndromes (ACS) have increased coronary sinus (CS) blood temperature compared with the right atrium (RA). The aim of this study was to investigate whether there is a correlation between systemic inflammatory indexes and CS temperature and whether there is a difference in CS temperature between patients with single vs. multivessel disease.Materials and methods  We included consecutive patients scheduled for coronary angiography for recent‐onset chest pain evaluation. We measured C‐reactive protein (CRP) levels in the study population. Coronary sinus and RA blood temperature measurements were performed by a 7F thermography catheter. ΔΤ was calculated by subtracting the RA from the CS blood temperature.Results  The study population comprised 53 patients with ACS, 25 patients with stable angina (SA) and 22 subjects without CAD (control group). ΔΤ was greater in patients with ACS and with SA compared with the control group (0·22 ± 0·10 °C, 0·18 ± 0·04 °C vs. 0·14 ± 0·07 °C, P < 0·01 for both comparisons). The ACS group had greater ΔΤ compared with the SA group, although the difference did not reach statistical significance (P = 0·09). Eighteen (39·1%) out of 46 patients with multivessel disease had three‐vessel disease and 28 (60·8%) had two‐vessel disease. ΔΤ between patients with multivessel and single vessel disease was similar (0·22 ± 0·01 °C, 0·19 ± 0·01 °C, P = 0·17). The levels of CRP were well correlated with ΔΤ (R = 0·35b, P < 0·01).Conclusions  Systemic inflammation is well correlated with CS temperature; thus, an inflammatory process could be the underlying mechanism for increased heat production from the myocardium.
C and N availability affects the 15N natural abundance of the soil microbial biomass across a cattle manure gradient
Authors: Dijkstra P. , Menyailo O. V. , Doucett R. R. , Hart S. C. , Schwartz E. , Hungate B. A. 
Published: March 2006

SummaryThe availability of C and N to the soil microbial biomass is an important determinant of the rates of soil N transformations. Here, we present evidence that changes in C and N availability affect the 15N natural abundance of the microbial biomass relative to other soil N pools. We analysed the 15N natural abundance signature of the chloroform‐labile, extractable, NO3–, NH4+ and soil total N pools across a cattle manure gradient associated with a water reservoir in semiarid, high‐desert grassland. High levels of C and N in soil total, extractable, NO3–, NH4+ and chloroform‐labile fractions were found close to the reservoir. The δ15N value of chloroform‐labile N was similar to that of extractable (organic + inorganic) N and NO3– at greater C availability close to the reservoir, but was 15N‐enriched relative to these N‐pools at lesser C availability farther away. Possible mechanisms for this variable 15N‐enrichment include isotope fractionation during N assimilation and dissimilation, and changes in substrate use from a less to a more 15N‐enriched substrate with decreasing C availability.
Decrease in thermal conductivity with increasing temperature in nearly dry sandy soil
Authors: Sakaguchi I. , Momose T. , Kasubuchi T. 
Published: March 2006

SummaryTo clarify the role of the water bridges between soil particles on the transfer of heat we studied the dependence of thermal conductivity (λ) and electrical conductivity (E) on temperature between 278 and 338 K of sand and sand mixed with kaolin in the nearly dry state. The thermal conductivity decreased as temperature increased in the sand at volumetric water contents less than 0.07 m3 m−3, but it increased in the sand–kaolin mixture over the measured range of water content. In the sand, the ratio of E in the soil solution to the electrical conductivity of pure water increased gradually with increasing water content at the water contents less than 0.05 m3 m−3 and was almost constant at larger water contents. The ratio of E of the sand–kaolin mixture increased with increasing water content, particularly at the lower temperature. For both samples the ratio of E decreased as temperature increased, which suggested that the conduction of heat decreased through the decrease in the water bridges as temperature increased. Because the decrease in λwith increasing temperature could not be explained by the transfer of latent heat transfer, we considered that the temperature dependence of λwas due not only to the transfer of latent heat but also to the thermal bridge of water. We conclude that the condensation, conduction and evaporation in series involved in the latent heat transfer take place mainly through the water films. Our experimental results will help to understand the mechanism of the latent heat transfer in soil with the water films surrounding the soil particles.
Lignin turnover in an agricultural field: from plant residues to soil‐protected fractions
Authors: Rasse D. P. , Dignac M.‐F. , Bahri H. , Rumpel C. , Mariotti A. , Chenu C. 
Published: March 2006

SummaryLignin has long been suspected to be a major source of stable carbon in soils, notably because of the recalcitrant nature of its polyphenolic structure relative to other families of plant molecules. However, lignin turnover studies have produced conflicting results, most of them suggesting that large proportions of plant‐residue lignin decompose within a year of incorporation into soils. Here, we propose a two‐reservoir model where lignin in undecomposed plant residue (Lp) can either reach soil fractions where it is somewhat protected from further decomposition (Ls) or is transformed to non‐lignin products. Model calibration data were obtained through compound‐specific 13C isotopic analyses conducted in a zero‐ to 9‐year chronosequence of maize monoculture after wheat in a temperate loam soil of the Paris basin. Lignin was quantified by CuO oxidation as VSC‐lignin, i.e. the sum of vanillil‐ (V), syringyl‐ (S) and coumaryl‐type (C) phenols. Model calibrations indicate that Lp has a turnover rate faster than 1 year and that 92% is mineralized as CO2 or transformed into other non‐lignin products, while only 8% reaches the Ls fraction. Estimated turnover rate of the Ls fraction was 0.05 years−1. The model also suggested that about half of Lp was not measured because it had been excluded from the samples in the process of sieving at 5 mm. In conclusion, the model indicates that chemical recalcitrance alone is not sufficient to explain VSC‐lignin turnover in soils, and that, functionally, the most relevant mechanism appears to be the transfer of VSC‐lignin molecules and fragments from decomposing plant tissues to soil‐protected fractions.
Trading safety for food: evidence from gut contents in roach and bleak captured at different distances offshore from their daytime littoral refuge
Authors: MACIEJ GLIWICZ Z. , SLON JAROSLAW , SZYNKARCZYK IWONA 
Published: March 2006

Summary1. Regular diel habitat shifts in roach were detected by hydro‐acoustics in five moderately eutrophic, stratifying (maximum depth 24–27 m) and approximately circular lakes (of surface area 15, 75, 125, 300 and 900 ha and diameters 250, 600, 1000, 1700 and 2600 m) in north‐eastern Poland in the years 1998–2000, when the lakes were free of smelt and other typical offshore planktivores, and their offshore areas were completely free of fish during the day.2. The diel change in roach distribution was shown to assume a similar pattern in each lake: fish migrated from a daytime littoral refuge towards the centre of the lake at dusk, and returned to the littoral refuge at dawn. After sunset, fish gradually dispersed offshore until they covered the entire lake area in each of the three smaller lakes. In each of the two larger lakes, only small numbers of fish were seen in the central area at night, implying that the centre of the lake retained high food availability throughout the summer.3. Inshore–offshore gradients in zooplankton prey density, body size, and numbers of eggs per clutch were weak or undetectable in the two smallest lakes, but strong and persistent in the three larger lakes, with Daphnia densities 5–30 times as high and body length 1.2–1.5 times as great in the central area as inshore.4. The likely increase in the potential predation risk with distance from the littoral daytime refuge was found to be compensated by increased food gains in those fish which moved offshore at dusk to feed within a short time window, when light intensity was lower to make the risk reduced, but still high enough to see zooplankton prey. The benefit because of increased prey acquisition was greatest in the centre of the largest lake (at 1300 m from the shore), as revealed from gut inspections of roach and bleak trawl‐sampled at different distances from the edge of the reed belt, and seen as a gradual, order‐of‐magnitude increase in the volume of food in the foregut, The food volume against distance‐from‐shore regression was highly significant on each of the four sampling dates in the largest lake, in spite of the wide variability of food volume in individual fish.
Trophic fractionation of carbon and nitrogen stable isotopes in Chironomus riparius reared on food of aquatic and terrestrial origin
Authors: GOEDKOOP WILLEM , ÅKERBLOM NINA , DEMANDT MARNIE H. 
Published: March 2006

Summary1. Trophic fractionation was studied in short‐term laboratory feeding experiments with larvae of the deposit‐feeding midge Chironomus riparius. Larvae were fed food of terrestrial (oats, peat) and aquatic origin (Spirulina, Tetraphyll®).2. By analysing both whole larvae and isolated gut contents we were able to distinguish between the isotopic signature of recently ingested food and that of assimilated carbon and nitrogen in body tissue. Additionally we studied the effects of microbial conditioning, i.e. the colonisation and growth on food particles of microbes, on the isotopic signal of food resources.3. Nitrogen fractionation for the different food types ranged from 0.67‰ to 2.68‰ between consumer and diet and showed that isotopic fractionation can be much lower than the value of 3.4‰ that is commonly assumed.4. Microbial degradation of food particles resulted in an approximate doubling of the δ15N in 8 days, from 6.24 ± 0.05‰ to 11.36 ± 0.56‰. Values for δ13C increased only marginally, from −20.66 ± 0.11‰ to −20.34 ± 0.12‰. These results show that microbial conditioning of food may affect dietary isotope signatures (in particular N) and, unless accounted for, could introduce an error in measures of trophic fractionation. Microbial conditioning could well account for some of the variation in fractionation reported in the literature.
Assessing the importance of a self‐generated detachment process in river biofilm models
Authors: BOULÊTREAU STÉPHANIE , GARABÉTIAN FRÉDÉRIC , SAUVAGE SABINE , SÁNCHEZ‐PÉREZ JOSÉ‐MIGUEL 
Published: March 2006

Summary1. Epilithic biofilm biomass was measured for 14 months in two sites, located up‐ and downstream of the city of Toulouse in the Garonne River (south‐west France). Periodical sampling provided a biomass data set to compare with simulations from the model of Uehlinger, Bürher and Reichert (1996: Freshwater Biology, 36, 249–263.), in order to evaluate the impact of hydraulic disturbance.2. Despite differences in application conditions (e.g. river size, discharge, frequency of disturbance), the base equation satisfactorily predicted biomass between low and high water periods of the year, suggesting that the flood disturbance regime may be considered a universal mechanism controlling periphyton biomass.3. However modelling gave no agreement with biomass dynamics during the 7‐month long low water period that the river experienced. The influence of other biomass‐regulating factors (temperature, light and soluble reactive phosphorus) on temporal biomass dynamics was weak.4. Implementing a supplementary mechanism corresponding to a temperature‐dependent self‐generated loss because of heterotrophic processes allowed us to accurately reproduce the observed pattern: a succession of two peaks. This case study suggests that during typical summer low water periods (flow stability and favourable temperature) river biofilm modelling requires self‐generated detachment to be considered.
The evidence for shrub expansion in Northern Alaska and the Pan‐Arctic
Authors: TAPE KEN , STURM MATTHEW , RACINE CHARLES 
Published: March 2006

AbstractOne expected response to climate warming in the Arctic is an increase in the abundance and extent of shrubs in tundra areas. Repeat photography shows that there has been an increase in shrub cover over the past 50 years in northern Alaska. Using 202 pairs of old and new oblique aerial photographs, we have found that across this region spanning 620 km east to west and 350 km north to south, alder, willow, and dwarf birch have been increasing, with the change most easily detected on hill slopes and valley bottoms. Plot and remote sensing studies from the same region using the normalized difference vegetation index are consistent with the photographic results and indicate that the smaller shrubs between valleys are also increasing. In Canada, Scandinavia, and parts of Russia, there is both plot and remote sensing evidence for shrub expansion. Combined with the Alaskan results, the evidence suggests that a pan‐Arctic vegetation transition is underway. If continued, this transition will alter the fundamental architecture and function of this ecosystem with important ramifications for the climate, the biota, and humans.
Desertification in the Sahel: a reinterpretation
Authors: HEIN LARS , DE RIDDER NICO 
Published: March 2006

AbstractThe impact of human management, in particular livestock grazing, on the vegetation cover of the Sahel is still debated. In a range of studies, satellite images have been used to analyze the development of the Sahelian vegetation cover over time. These studies did not reveal any significant degradation of the Sahel in the last two decades. In this paper, we examine the ecological assumptions underlying the use of satellite imagery to analyze degradation of the Sahel. Specifically, we analyze the variability of the rain‐use efficiency (RUE), which is often used as an indicator for the state of the vegetation cover. We detect a fundamental flaw in the way RUE has been handled in most remote sensing studies; they ignored the relation between annual rainfall variation and RUE. Because of the upward trend in annual rainfall that occurred during the 1980s and 1990s, this leads to a bias in the interpretation of the satellite images. In this paper, we show the importance of the variability in RUE for the analysis of remote sensing imagery of semiarid rangelands. Our analysis also shows that it is likely that there has been anthropogenic degradation of the Sahelian vegetation cover in the last two decades. This has important consequences for the debate on the impacts of grazing on semiarid rangelands. Furthermore, the occurrence of anthropogenic degradation is relevant to explain the magnitude of 20th century Sahelian droughts. The analyses also indicate that the population of the Sahel may be more vulnerable for droughts than currently assumed.