bluuebunny/crossref_metadata_2025_split huggingface dataset:
Understanding the Mechanism of Superoxide Reductase Promoted Reduction of Superoxide
Authors: Brines Lisa M. , Kovacs Julie A. 
Published: September 2006

AbstractSuperoxide reductases (SORs) are nonheme, iron‐containing enzymes which reduce superoxide (O2–) to hydrogen peroxide (H2O2) in anaerobic organisms. In contrast to the classical superoxide dismutases (SODs), SORs selectively reduce, rather than disproportionate, superoxide at an unusual [Fe(NHis)4SCys] catalytic site. Studies of the native enzyme and mutants have suggested the formation of a transient ferric‐(hydro)peroxide intermediate in SOR’s catalytic cycle, with subsequent protonation to yield hydrogen peroxide and a glutamate‐bound ferric resting state. With the synthesis of small molecular model compounds of the enzyme’s active site, analogous intermediates can be more thoroughly investigated in order to understand how the structure at the nonheme iron active site affects its function. Specific goals include the understanding of the role of the trans cysteinate in the promotion of SOR chemistry, as well as the role of the protons in the mechanism of the reaction. Because hydrogen peroxide formation requires two protons, investigation of the proton‐dependence of the formation of ferric‐(hydro)peroxo model complexes, as well as their subsequent reactivity with proton donors, yields important information about possible mechanisms. As new biochemical data on SORs become available, synthetic modeling, biophysical characterization, and DFT calculations continue to be important tools in the identification of viable mechanistic pathways.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Thermal Evolution of a MgAl Hydrotalcite‐Like Material Intercalated with Hexaniobate
Authors: Carriazo Daniel , Martín Cristina , Rives Vicente 
Published: September 2006

AbstractA MgAl hydrotalcite‐like material intercalated with hexaniobate has been prepared by the anion exchange method from the corresponding nitrate precursor; the sample and the oxides obtained upon its calcination were characterized by element chemical analysis, powder X‐ray diffraction, thermal analyses (thermogravimetric and differential), nitrogen adsorption‐desorption isotherms at –196 °C, transmission electron microscopy, and FT‐IR and UV/Vis spectroscopy. The results show the formation of a microporous hydrotalcite‐type solid with a gallery height of 7.2 Å where the H3Nb6O195– anions are oriented with their C3 axes perpendicular to the layers. This material preserves its layered structure upon calcination up to 400 °C; calcination above this temperature causes decomposition of the hexaniobate and the layered structure collapses, giving rise to amorphous mesoporous solids (Nb‐Mg‐Al‐O) with a large specific surface area (157 m2 g–1). At 800 °C crystallization of Mg4Nb2O9 takes place. FT‐IR studies on the acid‐basic properties carried out by pyridine and 2‐propanol adsorption, showed that all solids obtained through hydrotalcite calcination present Lewis‐type acid and Brönsted‐type basic sites. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Synthetic Approaches to α,β‐Unsaturated δ‐Lactones and Lactols
Authors: Boucard Valérie , Broustal Garance , Campagne Jean Marc 
Published: September 2006

AbstractThe synthesis of six‐membered unsaturated δ‐lactones has generated considerable interest, due to their occurrence in a large number of natural products possessing potent biological activities. This microreview attempts to illustrate the different strategies used to obtain such compounds, with a special emphasis on catalytic and asymmetric approaches. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
C–N Bond Formation by the Oxidative Alkylamination of Azines: Comparison of AgPy2MnO4 versus KMnO4 as Oxidant
Authors: Gulevskaya Anna V. , Maes Bert U. W. , Meyers Caroline , Herrebout Wouter A. , van der Veken Benjamin J. 
Published: September 2006

AbstractReports on the successful oxidative alkylamination of azines by the SNH‐reaction, with the use of alkylamines other than methylamine, are very scarce. Hitherto, the experimental limitation to extend oxidative amination of azines with NH3/KMnO4 to oxidative alkylamination is solely ascribed to the low solubility of KMnO4 in alkylamines and the increased sensitivity of alkylamines towards oxidation in comparison with ammonia. Our experimental data for the first time prove that there is also a substrate dependence in this type of reaction. 2‐Alkylamino‐5‐nitropyridines and 4‐alkylaminoquinazolines were smoothly obtained by the treatment of 3‐nitropyridine and quinazoline, respectively, with alkylamine/AgPy2MnO4. Although KMnO4 still gives moderate to good results with 3‐nitropyridine, it is completely useless for reactions with quinazoline with the same alkylamines. The use of AgPy2MnO4 was found to give equal or superior results to those of KMnO4 depending on the alkylamine and the substrate used and therefore seems to be a promising general oxidant for successful oxidative alkylaminations. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Interrill soil erosion processes and their interaction on low slopes
Authors: Asadi H. , Ghadiri H. , Rose C. W. , Rouhipour H. 
Published: September 2006

AbstractSoil erosion by water is mostly the result of rainfall‐driven and runoff‐driven processes taking place simultaneously during a storm event. However, the effect of interaction between these two erosion processes has received limited attention. Most laboratory experiments indicate that the rate of erosion in a rain‐impacted flow is greater than for un‐impacted flows of similar depth and velocity; however, negative interaction between the two processes has also been reported. There is no provision for any such interaction in any of the current erosion models. This paper reports on the results of a number of exact experiments on three soil types carried out in the flume of Griffith University's large rainfall simulator to study interaction between rain and runoff processes. The results show that interaction is generally positive under approximately steady state condition and there is very limited sign of negative interaction reported by others. Results provide strong evidence that raindrops continuously peel fine sediment from larger stable aggregates. This mechanism could be the reason for positive interaction during simultaneous rainfall and flow driven erosion in well aggregated soils as a result of increased fine particles in the eroded sediment. Strong positive interaction between rain and runoff erosion also occurs for medium to large aggregates. This strongly suggests that mechanisms that are not well understood are operational. It is quite possible that particle movement can be stimulated by rolling or creeping in a size‐selective manner. Indeed, such additional mechanisms may well be largely responsible for the positive interaction observed between rain and surface flow. Copyright © 2006 John Wiley & Sons, Ltd.
Assessment of adaptive and heuristic time stepping for variably saturated flow
Authors: D'Haese C. M. F. , Putti M. , Paniconi C. , Verhoest N. E. C. 
Published: September 2006

AbstractThe performance of improved initial estimates and ‘heuristic’ and ‘adaptive’ techniques for time step control in the iterative solution of Richards equation is evaluated. The so‐called heuristic technique uses the convergence behaviour of the iterative scheme to estimate the next time step whereas the adaptive technique regulates the time step on the basis of an approximation of the local time truncation error. The sample problems used to assess these various schemes are characterized by nonuniform (in time) boundary conditions, sharp gradients in the infiltration fronts, and discontinuous derivatives in the soil hydraulic properties. It is found that higher order initial solution estimates improve the convergence of the iterative scheme for both the heuristic and adaptive techniques, with greater overall performance gains for the heuristic scheme, as could be expected. It is also found that the heuristic technique outperforms the adaptive method under strongly nonlinear conditions. Previously reported observations suggesting that adaptive techniques perform best when accuracy requirements on the numerical solution are very stringent are confirmed. Overall both heuristic and adaptive techniques have their limitations, and a more general or mixed time stepping strategy combining truncation error and convergence criteria is recommended for complex problems. Copyright © 2006 John Wiley & Sons, Ltd.
Glutathione peroxidase 1 and a high cellular glutathione concentration are essential for effective organic hydroperoxide detoxification in astrocytes
Authors: Liddell Jeff R. , Dringen Ralf , Crack Peter J. , Robinson Stephen R. 
Published: September 2006

AbstractOrganic hydroperoxides are produced in the eicosanoid metabolism and by lipid peroxidation. To examine the contribution of glutathione peroxidase‐1 (GPx1) and glutathione (GSH) in the disposal of organic hydroperoxides in brain astrocytes, primary astrocyte cultures from wild type or GPx1‐deficient (GPx1(−/−)) mice were exposed to cumene hydroperoxide (CHP). After application of 100 μM CHP, the peroxide disappeared quickly from the incubation medium of wild type cells with a half‐life of 9 min, whereas CHP clearance was strongly retarded in GPx1(−/−) astrocytes. Depletion of GSH by pre‐incubation with buthionine sulfoximine (BSO) significantly slowed CHP clearance by wild type astrocytes, while almost completely preventing peroxide disposal by GPx1(−/−) cells. In contrast, the catalase inhibitor 3‐aminotriazole (3AT) had no effect on CHP clearance. Application of CHP to wild type astrocytes was followed by a rapid and transient accumulation of GSSG, whereas in GPx1(−/−) cells no increase in the GSSG content was detected. Astrocytes from both mouse lines remained viable for up to 24 h following CHP exposure, however depletion of cellular GSH by pre‐treatment with BSO compromised the viability of astrocytes, an effect that was stronger in GPx1(−/−) than in wild type cells. This cell death was almost completely prevented by iron chelators, whereas pre‐incubation with iron increased CHP toxicity. These novel data demonstrate that the toxicity of organic hydroperoxides in astrocytes is iron‐mediated, and that an intact GSH system is required for the effective removal of organic hydroperoxides and for protection from these peroxides. © 2006Wiley‐Liss, Inc.
Factors related to potentially harmful behaviors towards disabled older people by family caregivers in Japan
Authors: Sasaki Megumi , Arai Yumiko , Kumamoto Keigo , Abe Koji , Arai Asuna , Mizuno Yoko 
Published: September 2006

AbstractObjectiveThe purpose of the present study was to examine factors related to potentially harmful behaviors (PHB) by family caregivers towards their older family members.MethodsFour hundred and twelve pairs of disabled older adults and their family caregivers participated in the study. All of these disabled older adults were users of visiting nursing services under the public Long‐Term Care insurance system, who resided in one of the eight catchment areas of visiting nursing services in Kyoto Prefecture, Japan. The caregivers were asked to complete questionnaires in relation to their PHB towards their older family members, caregiver burden, patient‐caregiver kinship, behavioral disturbances of their older adult, age and sex. Visiting nurses obtained the following information regarding the older adults: the severity of dementia; the severity of physical impairment; age and sex.ResultsMore than 30% of the caregivers admitted PHB towards their older family members. The most frequently reported PHB included verbal aggression (16.8%) and ignoring (13.6%). A logistic regression analysis revealed that adult children (OR = 2.69, 95%CI = 1.23–5.89, p = 0.013) and caregivers of disabled older people with behavioral disturbances (OR = 3.61, 95%CI = 1.65–7.90, p < 0.01) were more likely to show PHB.ConclusionsIn the present study, PHB towards the older people by family caregivers was associated with patients' behavioral disturbances and patient‐caregiver kinship, i.e. an adult child as a caregiver. These findings should be taken into account when planning strategies to prevent PHB by family members. Copyright © 2006 John Wiley & Sons, Ltd.
Screening for amnestic mild cognitive impairment and early Alzheimer's disease with M@T (Memory Alteration Test) in the primary care population
Authors: Rami L. , Molinuevo J. L. , Sanchez‐Valle R. , Bosch B. , Villar A. 
Published: September 2006

AbstractObjectivesTo design and validate a new screening test for amnestic Mild Cognitive Impairment (A‐MCI) and early stage Alzheimer's disease (AD).MethodsWe develop a verbal episodic and semantic memory test: the Memory Alteration Test (M@T). Discriminative validity was assessed in a population sample of 400 aged individuals from primary care population centres in Barcelona, Spain, 50 patients with A‐MCI according to Petersen et al. criteria, and 66 with early AD (Global Deterioration Scale—4 stage) according to the NINCDS‐ADRDA criteria.ResultsThe M@T is quick, 5‐min, and easy to administer and to score. M@T mean scores were significantly different between all groups: 41.4 (SD = 4.9) in the primary care population, 31.5 (SD = 3.9) in the A‐MCI group and 21.8 (SD = 4.9) in early AD. A cut‐off score of 37 points had a sensitivity of 96% and a specificity of 79% for A‐MCI diagnosis (AUC = 0.932). A cut‐off score of 28 points had a sensitivity of 92% and a specificity of 98% for early AD diagnosis (AUC = 0.99) and a sensitivity of 87 % and specificity of 82% to differentiate between A‐MCI and AD patients.ConclusionThe M@T provides efficient and valid screening for A‐MCI and early stage AD, and discriminates between A‐MCI and early AD patients. Copyright © 2006 John Wiley & Sons, Ltd.
Detecting subtle hydrochemical anomalies with multivariate statistics: an example from ‘homogeneous’ groundwaters in the Great Artesian Basin, Australia
Authors: O'Shea Bethany , Jankowski Jerzy 
Published: September 2006

AbstractThe major ion composition of Great Artesian Basin groundwater in the lower Namoi River valley is relatively homogeneous in chemical composition. Traditional graphical techniques have been combined with multivariate statistical methods to determine whether subtle differences in the chemical composition of these waters can be delineated. Hierarchical cluster analysis and principal components analysis were successful in delineating minor variations within the groundwaters of the study area that were not visually identified in the graphical techniques applied. Hydrochemical interpretation allowed geochemical processes to be identified in each statistically defined water type and illustrated how these groundwaters differ from one another. Three main geochemical processes were identified in the groundwaters: ion exchange, precipitation, and mixing between waters from different sources. Both statistical methods delineated an anomalous sample suspected of being influenced by magmatic CO2 input. The use of statistical methods to complement traditional graphical techniques for waters appearing homogeneous is emphasized for all investigations of this type. Copyright © 2006 John Wiley & Sons, Ltd.
Incremental distributed modelling investigation in a small agricultural catchment: 2. Erosion and phosphorus transport
Authors: Taskinen Antti , Bruen Michael 
Published: September 2006

AbstractDistributed physically based erosion and phosphorus (P) transport models, run by the overland flow model described in Taskinen and Bruen (2006. Hydrological Processes 20: this issue), are described. In the erosion model, the additional components to the basic model were the outflow of the particles by infiltration and a new model component, i.e. deposition when rainfall stops. Two ways of calculating the shielding factor due to the flow depth were compared. The P transport model had both dissolved P (DP) and particulate P (PP) components. The processes included in the DP model were desorption from the soil surface, advection, storage in the overland flow and infiltration. The PP model accounted for advection, storage in the flow, infiltration, detachment from the soil surface by flow and rainfall and deposition both when transport capacity of suspended solids (SS) is exceeded and when rainfall ceases. When the models were developed and validated in small agricultural fields of cohesive soil types in southern Finland, comparisons were made between corresponding processes and the significance of added components were estimated in order to find out whether increased model complexity improves the model performance. The sedigraphs were found to follow the dynamics of rainfall, emphasizing the importance of the rainfall splash component. The basic model was too slow to react to changes in rainfall and flow rates, but infiltration and deposition that acts during the cessation in rainfall improved the model significantly by enabling the modelled SS to fall sharply enough. The shielding effect of flow depth from the splash detachment was found to play a significant role. Transport capacity should also be included in erosion models when they are applied to cohesive soils. In this study, the Yalin method worked well. A strong correlation was obvious between the measured SS and total P concentrations, indicating that the main form of P in runoff is PP. This emphasizes the importance of a good sediment transport model in P transport modelling. The submodel used for DP desorption from the soil surface produced plausible results without any calibration. Copyright © 2006 John Wiley & Sons, Ltd.
Basic data on the hydrology of Lakes Ohrid and Prespa
Authors: Popovska Cvetanka , Bonacci Ognjen 
Published: September 2006

AbstractThis paper deals with hydrological analyses of Lakes Ohrid and Prespa. The watersheds and the lakes themselves are shared by three countries: Albania, Greece and Macedonia. As a result of insufficient interstate scientific cooperation and inexistence of data exchange, the lakes and their watersheds are not fully investigated regarding hydrology and hydrogeology. This paper represents a first attempt at a complete hydrological analysis based on data from the Macedonian side. This is not considered to be a particular deficiency, because over 60% of the lakes' watersheds and the lakes themselves belong to Macedonia, where a great number of reliable and long‐term data series of hydrometeorological observations exist. The Prespa lakes do not have surface outflow and are connected with Lake Ohrid by underground karst conduits. Because of this, from the hydrological point of view, the lakes and their watersheds cannot be analysed separately. The changes of the regime of the air temperature and the rainfall distribution have been investigated in this report. An increase of the maximum and decrease of the minimum annual air temperatures, as well as a decrease of annual precipitation sums has been determined. Also, a statistically significant descending trend of water level in both lakes has been confirmed, with a statement that the water level decrease in Lake Prespa is extremely alarming. From 1985 to 1995 the water level in Lake Prespa has dropped by more than 5 m. The main reasons for this cannot be identified easily because there are no data on water use quantities from all three countries. As the lakes represent unique natural, ecological and economical water resources in a region suffering water shortage, we plead for a strengthening of international support in activities on salvation of both lakes. A prerequisite for this is the water balance calculation and common cooperation in sustainable water resources management of the lakes. Copyright © 2006 John Wiley & Sons, Ltd.
Enhanced expression of cholecystokinin‐2 receptor promotes the progression of colon cancer through activation of focal adhesion kinase
Authors: Yu Hong‐Gang , Tong Shi‐Lun , Ding You‐Ming , Ding Jian , Fang Xiang‐Min , Zhang Xian‐Feng , Liu Zhu‐Jun , Zhou Yan‐Hong , Liu Qi‐Sheng , Luo He‐Sheng , Yu Jie‐Ping 
Published: September 2006

AbstractFocal adhesion kinase (FAK) is suggested to be intimately involved in the progression of malignancies. Our previous research has demonstrated that activation of cholecystokinin‐2 receptor (CCK2R) by gastrin stimulates a rapid activation of FAK pathway in human colon cancer cells. The purpose of this study is to determine the role of CCK2R and FAK in the progression of colon cancer. In this study, matched tissue samples of primary colon cancer and adjacent normal colon mucosa from the same patient were collected from 45 patients with colon cancer undergoing surgical resection. The gastrin expression was detected using reverse transcription polymerase chain reaction (RT‐PCR). The CCK2R expression was examined by in situ hybridization and RT‐PCR. The expression of FAK and phosphorylated FAK at tyrosine 397 (phospho‐FAK) were detected using immunohistochemistry and immunoblotting. Colo320 and SW787, 2 colon cancer cell lines with or without CCK2R expression, were recruited in this study. Antisense oligonucleotide of FAK was used to block the expression of FAK. Invasiveness and motility of colon cancer cells were detected by Boyden chamber. In this series, enhanced expression of gastrin, CCK2R, FAK and phospho‐FAK were observed in colon cancer tissues. CCK2R expression correlated with expression of phospho‐FAK. Coexpression of CCK2R and phospho‐FAK associated with invasion and lymph node metastasis. Increased invasion and motility was induced by gastrin in Colo320 cells. Overexpression of CCK2R by stable transfection of CCK2R plasmid amplified this increase and incubation with 1 μM L‐365,260, a specific CCK2R antagonist, completely inhibited the effect of gastrin. FAK antisense largely blocked the increase of invasion and motility in Colo320 cells. Our data represent the evidence for the CCK2R regulating invasion and motility of colon cancer cells, and support a role of CCK2R in the progression of colon cancer. FAK play a critical role in this CCK2R‐mediated effect. © 2006 Wiley‐Liss, Inc.
Pretreatment serum endostatin as a prognostic indicator in metastatic gastric carcinoma
Authors: Woo In Sook , Kim Kyung‐Ae , Jeon Hae‐Myung , Hong Sook Hee , Rho Sang Young , Koh Su Jin , Lee Myung Ah , Byun Jae Ho , Kang Jin‐Hyung , Hong Young Seon , Lee Kyung Shik , Cho Chul‐Soo , Choi Myung Gyu , Chung In‐Sik 
Published: September 2006

AbstractEndostatin is the C‐terminal antiangiogenic fragment of the extracellular matrix protein collagen XVIII, and is generated by tumor‐derived proteases. The presence of serum endostatin in patients with gastric cancer has not been reported. The authors assessed the serum levels of endostatin in patients with gastric carcinoma and evaluated their association with the levels of vascular endothelial growth factor (VEGF) and the clinical outcome. A total of 107 patients with gastric cancer were included in the study. Pretherapeutic serum levels of endostatin and VEGF were measured using an ELISA, and compared with those in 23 healthy controls. The serum levels of endostatin and VEGF were higher in gastric cancer patients than in healthy controls (endostatin, 70.1 ± 16.6 vs. 52.2 ± 6.2 ng/mL [p < 0.001]; VEGF, 55.1 ± 7.6 vs. 32.1 ± 2.4 ng/mL [p < 0.001]; mean ± SD). Serum endostatin levels were significantly associated with the presence of distant metastases (r = 0.556, p < 0.001) and VEGF levels (r = 0.335, p < 0.001), but not with the depth of tumor invasion, differentiation, or regional lymph node status. A serum endostatin level above the 75th percentile of the distribution for the patients (79.2 ng/mL) was associated with a poor outcome (last follow‐up at 42 months; median survival time, 9 vs. 20 months [log‐rank, p = 0.017]; median time to progression, 5 vs. 10 months [log‐rank, p = 0.022]) in the patients with metastatic gastric cancer. The results suggest for the first time that an elevated serum level of endostatin at the diagnosis of metastatic gastric cancer could be predictive of a poor outcome. © 2006 Wiley‐Liss, Inc.