bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stromal biology of pancreatic cancer
Authors: Chu Gerald C. , Kimmelman Alec C. , Hezel Aram F. , DePinho Ronald A. 
Published: February 2007

AbstractThe genetic paradigm of cancer, focused largely on sequential molecular aberrations and associated biological impact in the neoplastic cell compartment of malignant tumors, has dominated our view of cancer pathogenesis. For the most part, this conceptualization has overlooked the dynamic and complex contributions of the surrounding microenvironment comprised of non‐tumor cells (stroma) that may resist, react to, and/or foster tumor development. Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal disease in which a prominent tumor stroma compartment is a defining characteristic. Indeed, the bulk of PDAC tumor volume consists of non‐neoplastic fibroblastic, vascular, and inflammatory cells surrounded by immense quantities of extracellular matrix, far exceeding that found in most other tumor types. Remarkably, little is known about the composition and physiology of the PDAC tumor microenvironment, in particular, the role of stroma in tumor initiation and progression. This review attempts to define key challenges, opportunities and state‐of‐knowledge relating to the PDAC microenvironment research with an emphasis on how inflammatory processes and key cancer pathways may shape the ontogeny of the tumor stroma. Such knowledge may be used to understand the evolution and biology of this lethal cancer and may convert these insights into new points of therapeutic intervention. J. Cell. Biochem. 101: 887–907, 2007. © 2007 Wiley‐Liss, Inc.
Tl(I)‐the strongest structure‐breaking metal ion in water? A quantum mechanical/molecular mechanical simulation study
Authors: Vchirawongkwin Viwat , Hofer Thomas S. , Randolf Bernhard R. , Rode Bernd M. 
Published: February 2007

AbstractStructural and dynamical properties of the Tl(I) ion in dilute aqueous solution have been investigated by ab initio quantum mechanics in combination with molecular mechanics. The first shell plus a part of the second shell were treated by quantum mechanics at Hartree‐Fock level, the rest of the system was described by an ab initio constructed potential. The radial distribution functions indicate two different bond lengths (2.79 and 3.16 Å) in the first hydration shell, in good agreement with large‐angle X‐ray scattering and extended X‐ray absorption fine structure spectroscopy results. The average first shell coordination number was found as 5.9, and several other structural parameters such as coordination number distributions, angular distribution functions, and tilt‐ and θ‐angle distributions were evaluated. The ion–ligand vibration spectrum and reorientational times were obtained via velocity auto correlation functions. The TlO stretching force constant is very weak with 5.0 N m−1. During the simulation, numerous water exchange processes took place between first and second hydration shell and between second shell and bulk. The mean ligand residence times for the first and second shell were determined as 1.3 and 1.5 ps, respectively, indicating Tl(I) to be a typical “structure‐breaker”. The calculated hydration energy of −84 ± 16 kcal mol−1 agrees well with the experimental value of −81 kcal mol−1. All data obtained for structure and dynamics of hydrated Tl(I) characterize this ion as a very special case among all monovalent metal ions, being the most potent “structure‐breaker”, but at the same time forming a distinct second hydration shell and thus having a far‐reaching influence on the solvent structure. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2007
Kinetic mechanism of the hydrogen abstraction reactions of the chlorine atoms with CH3CF2Cl and CH3CFCl2: A dual level direct dynamics study
Authors: Ji Yue‐meng , Zhao Xiao‐lei , Li Ze‐sheng , Liu Jing‐yao 
Published: February 2007

AbstractThe mechanisms of the reactions: CH3CFCl2 + Cl (R1) and CH3CF2Cl + Cl (R2) are studied over a wide temperature range (200–3000 K) using the dual‐level direct dynamics method. The minimum energy path calculation is carried out at the MP2/6‐311G(d,p) and B3LYP/6‐311G(d,p) levels, and energetic information is further refined by the G3(MP2) theory. The H‐abstraction from the out‐of‐plane for (R1) is the major reaction channel, while the in‐plane H‐abstraction is the predominant route of (R2). The canonical variational transition‐state theory (CVT) with the small‐curvature tunneling (SCT) correction method is used to calculate the rate constants. Using group‐balanced isodesmic reactions and hydrogenation reactions as working chemical reactions, the standard enthalpies of formation for CH3CFCl2, CH3CF2Cl, CH2CFCl2, and CH2CF2Cl are evaluated at the CCSD(T)/6‐311 + G(3df,2p)//MP2/6‐311G(d,p) level of theory. The results indicate that the substitution of fluorine atom for the chlorine atom leads to a decrease in the CH bond reactivity with a small increase in reaction enthalpies. Also, for all reaction pathways the variational effect is small and the SCT effect is only important in the lower temperature range on the rate constants. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2007
Computation of large systems with an economic basis set: Structures and reactivity indices of nucleic acid base pairs from density functional theory
Authors: Fan W. J. , Zhang R. Q. , Liu Shubin 
Published: February 2007

AbstractWe show here that an economic basis set can describe nucleic acid base pairs involving the hydrogen bond interactions in density functional calculations. The economic basis set in which the polarization function is added only to oxygen and nitrogen atoms of strong electronegativity can predict reliable geometric structures and dipole moment of nucleic acid base pairs, comparable to those obtained from the basis set of 6‐31G* in B3LYP calculations. Combining single point calculations with the standard basis set on the geometric structures optimized by the economic basis set, the present approach has predicted accurate natural bond orbital charge, binding energy, electronegativity, hardness, softness, and electrophilicity index. The principle for basis selection presented in this study can be regarded as a general guideline in the computation of large biological systems with considerably high accuracy and low computational expense. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2007
About paths with two blocks
Authors: Sahili Amine El , Kouider Mekkia 
Published: February 2007

AbstractThe function f(n) is defined to be the smallest integer such that any f(n)‐chromatic digraph contains all paths with two blocks P(k,j) with k + j = n − 1. El Sahili conjectured that f(n) = n. We prove in this paper that f(n) ≤ n + 1. Our argument yields a very short and direct proof of the Gallai–Roy result about directed paths. We also treat the problem under some supplementary conditions. One of them is used to give a simple proof of a result of Saks and Sós about claws. © 2007 Wiley Periodicals, Inc. J Graph Theory 55: 221–226, 2007
Effect of dietary supplementation with vitamin E on characteristics of vacuum‐packed lamb
Authors: de la Fuente Jesús , Díaz Maria Teresa , Álvarez Inmaculada , Lauzurica Sara , Cañeque Vicente , Pérez Concha 
Published: February 2007

AbstractThe effect of dietary vitamin E supplementation on lamb during vacuum‐packed storage was studied. Thirty‐six weaned male Manchego breed lambs were offered four dietary treatments (20, 270, 520 and 1020 mg vitamin E kg−1 feed). Lambs were fed the vitamin E‐supplemented diet from 13 until 26 kg live weight. Pieces of M. longissimus dorsi were stored under vacuum at 2 ± 1 °C in the dark and meat quality was assessed after 5, 14 and 28 days of storage. Dietary supplementation significantly increased the α‐tocopherol concentration in the muscle (P < 0.001). Initially, lipid oxidation, meat colour and bacterial load were similar in all groups. In meat of non‐supplemented lambs the thiobarbituric acid reactive substance value increased throughout storage, whereas in meat of supplemented lambs it did not increase. Meat pigments and discolouration proportion were significantly affected by storage time (P < 0.001). The bacterial load was low initially, but after 28 days of storage it was close to 7 log10 colony‐forming units (cfu) cm−2 and Enterobacteriaceae surpassed the limit of acceptability of 2.5 log10 cfu cm−2, making the lamb unsuitable for human consumption. Meat of supplemented lambs displayed less lipid oxidation than that of their non‐supplemented counterparts, while meat colour and bacterial load were not affected by supplementation. Copyright © 2007 Society of Chemical Industry
Iron and zinc concentration of native Andean potato cultivars from a human nutrition perspective
Authors: Burgos Gabriela , Amoros Walter , Morote Maximo , Stangoulis James , Bonierbale Merideth 
Published: February 2007

AbstractThe determination of iron (Fe) and zinc (Zn) concentrations in 49 native Andean potato varieties revealed significant genotypic variation. Comparison of mineral concentrations of 37 of these germplasm accessions grown in two highland locations further revealed significant variation due to environments and genotype × environment interaction. Concentrations in raw, peeled tubers ranged from 9 to 37 mg Fe kg−1 and 8 to 20 mg Zn kg−1 (dry weight) with accessions 703274 and 701165 showing the highest levels of Fe and Zn, respectively, in both locations. Fe and Zn concentrations were significantly and positively correlated on a fresh weight basis in each site. Assessment of Fe and Zn retention during processing revealed no losses due to cooking, and the only significant differences found in iron content of peeled versus unpeeled potatoes could be attributed to contamination with soil iron, as confirmed by elevated levels of aluminium in the samples. The ranges of micronutrient concentrations reported indicate ample genetic diversity that might be exploited in breeding programmes seeking to increase Fe and Zn levels in human diets. Copyright © 2007 Society of Chemical Industry
Enantiomeric resolution of new triazole compounds by high‐performance liquid chromatography
Authors: Lv Chunguang , Jia Guifang , Zhu Wentao , Qiu Jing , Wang Xinquan , Zhou Zhiqiang 
Published: February 2007

AbstractCellulose tris(3,5‐dimethylphenylcarbamate) (CDMPC) was synthesized and coated on aminopropylsilica to prepare a chiral stationary phase (CSP). HPLC methods were developed for the direct enantioseparation of 12 chiral triazole compounds on the CSP. The separations were made using normal phase methodology with a mobile phase consisting of n‐hexane‐alcohol (ethanol, 1‐propanol, 1‐butanol, 2‐propanol, and t‐butanol) in various portions. The column temperatures were studied for the optimization of the resolutions. The effects of structural features of the solutes on the discrimination between the enantiomers were examined. Baseline separation was easily obtained in many cases.
Determination of methylmalonic acid and glutaric acid in urine by aqueous‐phase derivatization followed by headspace solid‐phase microextraction and gas chromatography‐mass spectrometry
Authors: Li Ning , Deng Chunhui , Zhang Xiangmin 
Published: February 2007

AbstractIn this work, a novel technique of aqueous‐phase derivatization followed by headspace solid‐phase microextraction and gas chromatography‐mass spectrometry was developed for the determination of organic acids in urine. The analytical procedure involves derivatization of organic acids to their ethyl esters with diethyl sulfate, headspace sampling, and GC/MS analysis. The proposed method was applied to the determination of methylmalonic acid and glutaric acid in urine. The experimental parameters and method validation were studied. Optimal conditions were obtained: PDMS fiber, extraction temperature 55°C, extraction time 30 min, and 60 μL of diethyl sulfate as derivatization reagent with 2 mg of the ion pairing agent tetrabutylammonium hydrogensulfate. The method was linear over three orders of magnitude, and detection limits were 21 nM for methylmalonic acid and 34 nM for glutaric acid, respectively. Consequently, in‐situ derivatization/HS‐SPME/GC/MS is an alternative and powerful method for determination of organic acids as biomarkers in biological fluids.
Recent advances in capillary electrophoresis for biomarker discovery
Authors: Bakry Rania , Huck Christian W. , Najam‐ul‐Haq Muhammed , Rainer Matthias , Bonn Günther K. 
Published: February 2007

AbstractThe use of non‐invasive methods for detecting biomarkers opens a new era in patient care, since clinical investigators have long been searching for accurate and reproducible measurements of putative biomarkers. There are many factors which make this research challenging, beginning with lack of standardization of sample collection and continuing through the entire analytical procedure. Among the variety of methods so far used for biomarker screening, capillary electrophoresis represents a robust, reliable, and widely used analytical tool. This review will focus on recent applications of CE to the analysis of body fluids and tissues for identification of biomarkers.
Global boundary regularity for the $ \bar \partial $‐equation on q‐pseudoconvex domains
Authors: Ahn Heungju 
Published: February 2007

AbstractWe introduce a notion of q ‐pseudoconvex domain of new type for a bounded domain of ℂn and prove that for given a $ \bar \partial $‐closed (p, r)‐form, r ≥ q, that is smooth up to the boundary, there exists a (p, r – 1)‐form smooth up to the boundary which is a solution of $ \bar \partial $‐equation on a bounded q ‐pseudoconvex domain. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Cousin problem for systems of PDE
Authors: Shankar Shiva 
Published: February 2007

AbstractThis article formulates an additive Cousin type problem for systems of partial differential equations. The obstruction to the solution of this problem, like the obstruction in the classical Cousin problem, lies in a first cohomology module, viz. in an Ext1 module associated to the problem. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Some degenerate elliptic systems and applications to cusped plates
Authors: Jaiani G. , Schulze B.‐W. 
Published: February 2007

AbstractWe study the tension‐compression vibration of an elastic cusped plate under (all reasonable) boundary conditions at the cusped edge and given displacements at the non‐cusped edge and stresses at the upper and lower faces of the plate. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Cabergoline compared to levodopa in the treatment of patients with severe restless legs syndrome: Results from a multi‐center, randomized, active controlled trial
Authors: Trenkwalder Claudia , Benes Heike , Grote Ludger , Happe Svenja , Högl Birgit , Mathis Johannes , Saletu‐Zyhlarz Gerda M. , Kohnen Ralf ,   CALDIR study group
Published: February 2007

AbstractWe report the first large‐scale double‐blind, randomly assigned study to compare two active dopaminergic therapies for Restless Legs Syndrome (RLS), the dopamine agonist cabergoline (CAB) and levodopa/benserazide (levodopa). Patients with idiopathic RLS were treated with fixed daily doses of 2 or 3 mg CAB or 200 or 300 mg levodopa for 30 weeks. Efficacy was assessed by changes in the IRLS (International RLS Severity Scale) and by time to discontinuation of treatment due to loss of efficacy or augmentation. 361 of 418 screened patients (age 58 ± 12 years, 71% females) were randomly assigned and treated (CAB: n = 178; levodopa: n = 183) in 51 centers of four European countries. Baseline IRLS total score was 25.7 ± 6.8. The baseline‐adjusted mean change from baseline to week 6 in IRLS sum score was d = −16.1 in the CAB group and d = −9.5 in the levodopa group (d = −6.6, P < 0.0001). More patients in the levodopa group (24.0%) than in the CAB group (11.9%, P = 0.0029, log‐rank test) discontinued because of loss of efficacy (14.2% vs. 7.9%, P = 0.0290) or augmentation (9.8% vs. 4.0%, P = 0.0412). Adverse events (AEs) occurred in 83.1% of the CAB group and in 77.6% of the levodopa group. In both groups, most frequent AEs were gastrointestinal symptoms (CAB: 55.6%, levodopa: 30.6%, P < 0.0001). This first large‐scale active controlled study in RLS showed superior efficacy of cabergoline versus levodopa after a 30‐week long‐term therapy. Tolerability was found more favorable with levodopa than with cabergoline. © 2007 Movement Disorder Society
Endocrine status and markers of collagen synthesis and degradation in serum and urogenital tissue from women with and without stress urinary incontinence
Authors: Edwall Lena , Carlström Kjell , Jonasson Aino Fianu 
Published: February 2007

AbstractAimsTo investigate possible differences in androgen/estrogen status between patients with stress urinary incontinence (SUI) and healthy women's and to study possible associations between circulating estrogens and androgens on the one hand and collagen synthesis and metabolism in urogenital tissue on the other.MethodsMarkers of collagen turnover, the carboxy‐terminal propeptide of type I procollagen (PICP), the carboxy‐terminal telopeptide of type I collagen (ICTP), and the amino‐terminal propeptide of procollagen III (PIIINP), were assayed in urogenital tissue homogenates and estradiol‐17β (E2), total testosterone (T), and sex‐hormone‐binding globulin (SHBG) were assayed in peripheral serum from 58 patients with SUI and 30 urologically healthy women. Apparent concentrations of free testosterone (fT) were calculated from T, SHBG, and a fixed albumin value.ResultsSignificant positive correlations were found between E2 and PICP in controls and between E2 and ICTP in SUI patients without exogenous hormones. Significant negative and sometimes strong correlations were found between serum T and fT on the one hand and all three collagen turnover markers on the other. These correlations were strengthened when parity and/or body mass index (BMI) were reduced. No correlations between T and fT and collagen turnover markers were found in the controls. There were no significant differences between any of the groups in serum E2, T, or fT.ConclusionEstrogens may increase collagen turnover in urogenital tissue, however, the clinical significance of this is still unclear. Androgens may affect urogenital tissue negatively by slowing down collagen turnover, probably by inhibition of matrix metalloprotease (MMP) synthesis and/or activity. Urogenital tissue in SUI patients and in urologically healthy women may differ in androgen sensitivity. Neurourol. Urodynam. 26:410–415, 2007. © 2007 Wiley‐Liss, Inc.
Pre‐junctional α2‐adrenoceptors modulation of the nitrergic transmission in the pig urinary bladder neck
Authors: Hernández Medardo , Recio Paz , Victoria Barahona María , Bustamante Salvador , Peña Lidia , Cristina Martínez Ana , García‐Sacristán Albino , Prieto Dolores , Orensanz Luis M. 
Published: February 2007

AbstractAimsTo investigate the nitric oxide (NO)‐mediated nerve relaxation and its possible modulation by pre‐junctional α2‐adrenoceptors in the pig urinary bladder neck.MethodsUrothelium‐denuded bladder neck strips were dissected, and mounted in isolated organ baths containing a physiological saline solution (PSS) at 37°C and continuously gassed with 5% CO2 and 95% O2, for isometric force recording. The relaxations to transmural nerve stimulation (electrical field stimulation [EFS]) or exogenously applied NO were carried out on strips pre‐contracted with 1 µM phenylephrine (PhE) and treated with guanethidine (10 µM) and atropine (0.1 µM), to block noradrenergic neurotransmission and muscarinic receptors, respectively.ResultsEFS (0.2–1 Hz, 1 msec duration, 20 sec trains, current output adjusted to 75 mA) evoked frequency‐dependent relaxations which were abolished by the neuronal voltage‐activated Na+ channel blocker tetrodotoxin (TTX, 1 µM). These responses were potently reduced by the nitric oxide synthase (NOS) inhibitor NG‐nitro‐L‐arginine (L‐NOARG, 30 µM) and further reversed by the NO synthesis substrate L‐arginine (L‐ARG, 3 mM). The α2‐adrenoceptor agonist BHT‐920 (2 µM) reduced the electrically evoked relaxations, its effectiveness being higher on the responses induced by low frequency stimulation. BHT‐920‐elicited reductions were fully reversed by the α2‐adrenoceptor antagonist rauwolscine (RAW, 1 µM). Exogenous NO (1 µM–1 mM) induced concentration‐dependent relaxations which were not modified by BHT‐920, thus eliminating a possible post‐junctional modulation.ConclusionsThese results indicate that NO is involved in the non‐adrenergic non‐cholinergic (NANC) inhibitory neurotransmission in the pig urinary bladder neck, the release of NO from intramural nerves being modulated by pre‐junctional α2‐adrenoceptor stimulation. Neurourol. Urodynam. 26:578–583, 2007. © 2007 Wiley‐Liss, Inc.
Role of urothelial nerve growth factor in human bladder function
Authors: Birder Lori A. , Wolf‐Johnston Amanda , Griffiths Derek , Resnick Neil M. 
Published: February 2007

AbstractAimsTo test whether nerve growth factor (NGF) concentration in human bladder urothelium/suburothelium is related to detrusor overactivity (DO), bladder sensation, detrusor contractility, or other aspects of lower urinary tract function.Materials and MethodsConcentration of NGF was measured (using ELISA) in superficial bladder biopsies from 27 women (mean age 52 years, range 22–82) after comprehensive videourodynamics and bladder diary. Approximately half (12/27) showed clear DO and half did not.ResultsThere was no evidence for increased NGF concentration in subjects with DO (association negative by Mann–Whitney test, P = 0.23). NGF was not significantly associated with two measures of detrusor contractility (Spearman's r = −0.29, P = 0.17; r = −0.20, P = 0.33); nor with four measures inversely related to sensation: volume at strong desire to void and maximum capacity on cystometry (r = −0.13, P = 0.53; r = −0.23, P = 0.28), and maximum voided volume and mean daytime voided volume on bladder diary (r = −0.29, P = 0.16; r = −0.16, P = 0.44). It was significantly associated with 24‐hr urine output on bladder diary (Spearman's r = −0.55, P = 0.004).ConclusionsElevated NGF levels in human urothelium/suburothelium are not strongly associated with DO, detrusor contractility or increased bladder sensation. NGF levels are lower in subjects with higher 24‐hr urine output. This observation is consistent with a role for NGF in an active process (trafficking) involved in bladder filling. Neurourol. Urodynam. 26:405–409, 2007. © 2007 Wiley‐Liss, Inc.