bluuebunny/crossref_metadata_2025_split huggingface dataset:
Human umbilical cord–derived mesenchymal stem cells can secrete insulin in vitro and in vivo
Authors: Niki Boroujeni Zahra , Aleyasin Ahmad 
Published: May 2013

AbstractDiabetes mellitus is characterized by autoimmune destruction of pancreatic beta cells, leading to decreased insulin production. Differentiation of mesenchymal stem cells (MSCs) into insulin‐producing cells offers novel ways of diabetes treatment. MSCs can be isolated from the human umbilical cord tissue and differentiate into insulin‐secreting cells. Human umbilical cord–derived stem cells (hUDSCs) were obtained after birth, selected by plastic adhesion, and characterized by flow cytometric analysis. hUDSCs were transduced with nonintegrated lentivirus harboring PDX1 (nonintegrated LV‐PDX1) and was cultured in differentiation medium in 21 days. Pancreatic duodenum homeobox protein‐1 (PDX1) is a transcription factor in pancreatic development. Significant expressions of PDX1, neurogenin3 (Ngn3), glucagon, glucose transporter2 (Glut2), and somatostatin were detected by quantitative RT‐PCR (P < 0.05). PDX1 and insulin proteins were shown by immunocytochemistry analysis. Insulin secretion of hUDSCsPDX1+ in the high‐glucose medium was 1.8 μU/mL. They were used for treatment of diabetic rats and could decrease the blood glucose level from 400 mg/dL to a normal level in 4 days. In conclusion, our results demonstrated that hUDSCs are able to differentiate into insulin‐producing cells by transduction with nonintegrated LV‐PDX1. These hUDSCsPDX1+ have the potential to be used as a viable resource in cell‐based gene therapy of type 1 diabetes.
Hydrogen‐producing Escherichia coli strains overexpressing lactose permease: FT‐IR analysis of the lactose‐induced stress
Authors: Grube Mara , Dimanta Ilze , Gavare Marita , Strazdina Inese , Liepins Janis , Juhna Talis , Kalnenieks Uldis 
Published: May 2013

AbstractThe lactose permease gene (lacY) was overexpressed in the septuple knockout mutant of Escherichia coli, previously engineered for hydrogen production from glucose. It was expected that raising the lactose transporter activity would elevate the intracellular lactose concentration, inactivate the lactose repressor, induce the lactose operon, and as a result stimulate overall lactose consumption and conversion. However, overexpression of the lactose transporter caused a considerable growth delay in the recombinant strain on lactose, resembling to some extent the “lactose killing” phenomenon. Therefore, the recombinant strain was subjected to selection on lactose‐containing media. Selection on plates with 3% lactose yielded a strain with a decreased content of the recombinant plasmid but with an improved ability to grow and produce hydrogen on lactose. Macromolecular analysis of its biomass by means of Fourier transform‐infrared spectroscopy demonstrated that increase of the cellular polysaccharide content might contribute to the adaptation of E. coli to lactose stress.
Hedonic Evaluation over Short and Long Retention Intervals: The Mechanism of the Peak–End Rule
Authors: Geng Xiaowei , Chen Ziguang , Lam Wing , Zheng Quanquan 
Published: May 2013

ABSTRACTThe peak–end rule is used to explain how people make retrospective hedonic evaluations. This study advances our understanding of its mechanism by identifying the different effects of the rule on such evaluations over short and long retention intervals. The results of two experiments show that (i) respondents constructed their retrospective hedonic evaluations on the basis of the peak and end affects only over a short retention interval, not over a long one; and (ii) respondents relied on episodic information to construct their evaluations over a short retention interval, whereas they relied on both semantic and episodic information to construct their evaluations over a long retention interval. Our study also suggests that the “watershed” between short and long retention intervals is likely to lie between 3 and 7 weeks. Copyright © 2012 John Wiley & Sons, Ltd.
Flow‐injection chemiluminescence determination of olanzapine using N‐chlorosuccinimide–calcein reaction sensitized by zinc (II)
Authors: Zhao Fang , Fan Qi , Cai Huan 
Published: May 2013

ABSTRACTA novel, rapid and sensitive chemiluminescence (CL) method combined with flow‐injection (FI) has been established for the estimation of olanzapine. This method is based on the CL signal generated between N‐chlorosuccinimide and olanzapine in an alkaline medium in the presence of calcein and Zn(II). Under optimum conditions, the CL signal was proportional to the olanzapine concentration ranging from 1.0 × 10‐10 to 3.0 × 10‐7 g/mL. The detection limit is 8.9 × 10‐11 g/mL olanzapine (3σ) and the relative standard deviation for 3.0 × 10‐9 g/mL of olanzapine is 1.9% (n = 11). The current CL method was applied to determine olanzapine in pharmaceutical formulations and biological fluids with satisfactory results. The possible CL reaction mechanism is discussed briefly. Copyright © 2013 John Wiley & Sons, Ltd.
Frameshifting dynamics
Authors: Tinoco Ignacio , Kim Hee‐Kyung , Yan Shannon 
Published: May 2013

ABSTRACTTranslation of messenger RNA by a ribosome occurs three nucleotides at a time from start signal to stop. However, a frameshift means that some nucleotides are read twice or some are skipped, and the following sequence of amino acids is completely different from the sequence in the original frame. In some messenger RNAs, including viral RNAs, frameshifting is programmed with RNA signals to produce specific ratios of proteins vital to the replication of the organism. The mechanisms that cause frameshifting have been studied for many years, but there are no definitive conclusions. We review ribosome structure and dynamics in relation to frameshifting dynamics provided by classical ensemble studies, and by new single‐molecule methods using optical tweezers and FRET. 2013 Wiley Periodicals, Inc. Biopolymers 99: 1147–1166, 2013.
Structural identification of the metabolites of ganoderic acid B from Ganoderma lucidum in rats based on liquid chromatography coupled with electrospray ionization hybrid ion trap and time‐of‐flight mass spectrometry
Authors: Guo Xiaoyu , Shen Xuan , Long Jie , Han Jian , Che Qingming 
Published: May 2013

ABSTRACTGanoderic acid B (GAB), a representative triterpenoid in Ganoderma lucidum, possesses various pharmaceutical effects and has been used as a chemical marker in quality control of G. lucidum and related products. The metabolites of GAB in vivo after its oral administration to rats were investigated by liquid chromatography coupled with electrospray ionization hybrid ion trap and time‐of‐flight mass spectrometry. A total of 14 metabolites of GAB in rat plasma, bile and various organs were detected and identified by direct comparison with the authentic compounds and their characteristic mass fragmentation patterns. The results showed that oxidization and hydroxylation were the common metabolic pathways for GAB in rats. Moreover, some reduction metabolites of GAB were detected in rat kidney and stomach and glucuronidation only appeared in rat bile. This is the first report on the metabolites of GAB in vivo. Copyright © 2013 John Wiley & Sons, Ltd.
LC‐MS/MS determination of bakkenolide D in rats plasma and its application in pharmacokinetic studies
Authors: Dai Dongmei , Pei Lixia , Tang Lin , Chen Feng , Chen Xiuping 
Published: May 2013

ABSTRACTA sensitive and rapid liquid chromatography–tandem mass spectrometry (LC‐MS/MS) method was developed and validated for determination of bakkenolide D (BD), which was further applied to assess the pharmacokinetics of BD. In the LC‐MS/MS method, the multiple reaction monitoring mode was used and columbianadin was chosen as internal standard. The method was validated over the range of 1–800 ng/mL with a determination coefficient >0.999. The lower limit of quantification was 1 ng/mL in plasma. The intra‐ and inter‐day accuracies for BD were 91–113 and 100–104%, respectively, and the inter‐day precision was <15%. After a single oral dose of 10 mg/kg of BD, the mean peak plasma concentration of BD was 10.1 ± 9.8 ng/mL at 2 h. The area under the plasma concentration–time curve (AUC0–24 h) was 72.1 ± 8.59 h ng/mL, and the elimination half‐life (T1/2) was 11.8 ± 1.9 h. In case of intravenous administration of BD at a dosage of 1 mg/kg, the AUC0–24 h was 281 ± 98.4 h⋅ng/mL, and the T1/2 was 8.79 ± 0.63 h. Based on these results, the oral bioavailability of BD in rats at 10 mg/kg is 2.57%. Copyright © 2013 John Wiley & Sons, Ltd.
Influence of compound danshen tablet on the pharmacokinetics of losartan and its metabolite EXP3174 by liquid chromatography coupled with mass spectrometry
Authors: Yuan Yongfang , Zhang Hai , Ma Weina , Sun Sen , Wang Benwei , Zhao Liang , Zhang Guoqing , Chai Yifeng 
Published: May 2013

ABSTRACTLosartan is an effective anti‐hypotension drug frequently used in clinic. Compound danshen tablet (CDST) is an important traditional Chinese multiherbal formula composed of Danshen, Sanqi and Bingpian, which is widely used for the treatment of cardiovascular and cerebrovascular diseases in China. More often, losartan and CDST are simultaneously used for the treatment of anti‐hypertension in the clinic. The aim of this study was to compare the pharmacokinetics of losartan and EXP3174 after oral administration of single losartan and both losartan and CDST, and to investigate the influence of CDST on the pharmacokinetics of losartan and its metabolite EXP3174. Male Sprague–Dawley rats were randomly assigned to two groups: a losartan‐only group and a losartan and CDST group. Plasma concentrations of losartan and EXP3174 were determined by LC‐MS at designated points after drug administration, and the main pharmacokinetic parameters were estimated. It was found that there were significant differences (p < 0.05) between the pharmacokinetic parameters of losartan and EXP3174, which showed that CDST influenced the metabolism and excretion of losartan in vivo. The result could be used for clinical medication guidance of losartan and CDST to avoid the occurrence of adverse reactions. Copyright © 2013 John Wiley & Sons, Ltd.
Development and validation of a sensitive method for simultaneous determination of rosuvastatin and N‐desmethyl rosuvastatin in human plasma using liquid chromatography/negative electrospray ionization/tandem mass spectrometry
Authors: Lee H. K. , Ho C. S. , Hu M. , Tomlinson B. , Wong C. K. 
Published: May 2013

ABSTRACTA sensitive and specific liquid chromatography tandem mass spectrometric method was developed and validated for the simultaneous determination of rosuvastatin (ROS) and N‐desmethyl rosuvastatin (NOR‐ROS) in human plasma using deuterium‐labeled internal standards. The plasma samples were prepared using liquid–liquid extraction with diethyl ether. Chromatographic separation was accomplished on an Xterra MS C18 column. The mobile phase consisted of a gradient mixture of 15 µmol/L ammonium acetate in water and in methanol, maintained at a flow rate of 0.4 mL/min. Mass spectrometric detection was carried out in negative electrospray ionization mode and monitored by quantification and qualification transitions for each analyte. Using 300 μL plasma samples, the lower limits of quantification of ROS and NOR‐ROS were 0.05 and 0.02 µg/L respectively. The linearity of ROS and NOR‐ROS ranged from 0.05 to 42 and 0.02 to 14 µg/L respectively. The relative standard deviations of ROS and NOR‐ROS were <13 and 9%, respectively, while the deviations from expected values were within −4.7–9.8 and −5.2–4.6%, respectively. The present method offered high sensitivity and was successfully applied to a 24 h pharmacokinetic study of ROS and NOR‐ROS in healthy subjects receiving a single dose of 10 mg ROS. Copyright © 2013 John Wiley & Sons, Ltd.
Percutaneous closure of patent ductus arteriosus in small infants with significant lung disease may offer faster recovery of respiratory function when compared to surgical ligation
Authors: Abu Hazeem Anas A. , Gillespie Matthew J. , Thun Haley , Munson David , Schwartz Matthew C. , Dori Yoav , Rome Jonathan J. , Glatz Andrew C. 
Published: May 2013

ObjectivesTo describe our experience with percutaneous closure of patent ductus arteriosus (PDA) in small infants and compare outcomes to matched surgical patients.BackgroundLigation via thoracotomy has been used to close PDAs in small infants, but has been associated with respiratory and hemodynamic compromise. We hypothesized that percutaneous closure would offer faster recovery of respiratory function.MethodsPatients <4 kg requiring positive pressure ventilation who underwent percutaneous PDA closure between January 2000 and April 2012 were reviewed and matched to contemporary surgical patients on gestational age (GA), birth weight (BW), procedure weight (WT), and ventilation mode. Patients returned to baseline respiratory status when the product of mean airway pressure and FiO2 returned to pre‐procedural levels.ResultsEight matched pairs were included. Median BW, GA, and WT were 1.43 kg (0.52–2.97), 29.8 weeks (24–39), and 2.8 kg (2.2–3.9) for catheter patients and 1.55 kg (0.48–3.04), 29 weeks (23–37), and 2.75 kg (2.3–4.2) for surgical patients. Complete PDA closure occurred in all. The median time to return to baseline respiratory status was significantly shorter in the percutaneous group (17 hr (range 0–113) vs. 53 hr (range 13–219), P < 0.05). In the percutaneous group, two patients developed mild aortic coarctation, one mild left pulmonary artery stenosis, and four femoral vascular thromboses which all resolved with medical therapy. Surgical complications included significant respiratory and cardiac compromise, rib fractures and urinary retention.ConclusionsPercutaneous closure of PDA in small infants on respiratory support is equivalent in safety and efficacy and may offer shorter recovery time than surgical ligation. © 2013 Wiley Periodicals, Inc.
Deprotonation ofC‐Alkyl Groups of Cationic Triruthenium Clusters Containing CyclometalatedC‐Alkylpyrazinium Ligands: Experimental and Computational Studies
Authors: Cabeza Javier A. , Fernández‐Colinas José M. , García‐Álvarez Pablo , Pérez‐Carreño Enrique , Pruneda Vanessa , Van der Maelen Juan F. 
Published: May 2013

AbstractTheC‐alkyl groups of cationic triruthenium cluster complexes of the type [Ru3(μ‐H)(μ‐κ2N1,C2 ‐L)(CO)10]+(HL represents a genericC‐alkyl‐N‐methylpyrazium species) have been deprotonated to give kinetic products that contain unprecedentedC‐alkylidene derivatives and maintain the original edge‐bridged decacarbonyl structure. When the starting complexes contain variousC‐alkyl groups, the selectivity of these deprotonation reactions is related to the atomic charges of the alkyl H atoms, as suggested by DFT/natural‐bond orbital (NBO) calculations. Three additional electronic properties of theC‐alkyl CH bonds have also been found to correlate with the experimental regioselectivity because, in all cases, the deprotonated CH bond has the smallest electron density at the bond critical point, the greatest Laplacian of the electron density at the bond critical point, and the greatest total energy density ratio at the bond critical point (computed by using the quantum theory of atoms in molecules, QTAIM). The kinetic decacarbonyl products evolve, under appropriate reaction conditions that depend upon the position of theC‐alkylidene group in the heterocyclic ring, toward face‐capped nonacarbonyl derivatives (thermodynamic products). The position of theC‐alkylidene group in the heterocyclic ring determines the distribution of single and double bonds within the ligand ring, which strongly affects the stability of the neutral decacarbonyl complexes and the way these ligands coordinate to the metal atoms in the nonacarbonyl products. The mechanisms of these decacarbonylation processes have been investigated by DFT methods, which have rationalized the structures observed for the final products and have shed light on the different kinetic and thermodynamic stabilities of the reaction intermediates, thus explaining the reaction conditions experimentally required by each transformation.
Adsorption Sequence of Multifunctional Groups: A Study on the Reaction Pathway and the Adsorption Structure of Homocysteine on the Ge(100) Surface
Authors: Park Youngchan , Lee Myungjin , Lee Hangil 
Published: May 2013

AbstractWe investigated the adsorption mechanism of homocysteine (HSCH2CH2CH(NH2)COOH) on the Ge(100) surface along with its electronic structures and adsorption geometries to determine the sequence of adsorption of this amino acid′s functional groups using core‐level photoemission spectroscopy (CLPES) in conjunction with density functional theory (DFT) calculations. We found that the “SH‐dissociated OH‐dissociated N‐dative‐bonded structure” and the “SH‐dissociated OH‐dissociation‐bonded structure” were preferred at a monolayer (ML) coverage of 0.30 (lower coverage) and 0.60 (higher coverage), respectively. The “SH‐dissociated OH‐dissociated N‐dative‐bonded structure” was the most stable structure. Moreover, we systematically confirmed the sequence of adsorption of the functional groups of the homocysteine molecule on the Ge(100) surface, which is thiol group (SH), carboxyl group (COOH), and amine group (NH2).
First Evidence of a Phase Transition in a High‐Pressure Metal Iodate: Structural and Thermal Studies of AgIO3 Polymorphs
Authors: Suffren Yan , Gautier‐Luneau Isabelle , Darie Céline , Goujon Céline , Legendre Murielle , Leynaud Olivier 
Published: May 2013

AbstractA new phase of silver iodate, β‐AgIO3, was obtained at 2.7 GPa by heating the α‐AgIO3 precursor above 240 °C. β‐AgIO3 is the first iodate obtained at high pressure that stabilizes under normal conditions. The crystal structure was determined by X‐ray powder diffraction and Rietveld refinement. In comparison to α‐AgIO3, which crystallizes in the Pbc21 acentric orthorhombic space group with the lattice parameters a = 7.265(2) Å, b = 15.17(4) Å, c = 5.786(2) Å, and V = 638(2) Å3, β‐AgIO3 crystallizes in the Pbca centric orthorhombic space group, with the following parameters: a = 6.137(2) Å, b = 16.980(4) Å, c = 5.827(1) Å, and V = 607.3(3) Å3. Differential thermal analysis under high pressure (2.7 GPa) and structural studies showed an endothermic transformation at 260 °C corresponding to a first‐order reconstructive phase transition from α‐AgIO3 to β‐AgIO3. The thermal behaviors of α‐AgIO3 and β‐AgIO3 were studied by differential scanning calorimetry at ambient pressure and in situ temperature‐dependent X‐ray powder diffraction.
Can Diels–Alder Reactions Lead to trans‐Fused Products? A Computational Study of the Competitive [4+2] and [2+4] Cycloaddition of Dienes to α‐Aryl‐Substituted Cyclohexenones
Authors: Bakalova Snezhana M. , Santos A. Gil 
Published: May 2013

AbstractThe Diels–Alder reaction is one of the most interesting processes known in organic chemistry. Its one‐step nature, which allows exceptional control of the stereoselectivity of the reaction, is one of its most important characteristics. However, it is also a limitation of the process, as it prevents the formation of trans products. In spite of this, it is believed that trans products can be formed in two‐step Diels–Alder reactions, and there is a classic example that illustrates this possibility. In this paper we study this system by theoretical methods and have concluded that not only the reported Diels–Alder reaction follows a one‐step mechanism, but also that the trans product observed by the authors can only originate by a [3,3] sigmatropic rearrangement of a previously formed Diels–Alder intermediate. The study of a model system also suggests that trans fusion in two‐step Diels–Alder reactions will not happen under conventional reaction conditions as the transition states involved in such processes would have prohibitive activation energies. The large calculated values result from very poor stabilization of the zwitterionic intermediate when it adopts the conformation that allows the trans approach of the diene moiety to the activated dienophile. The analysis of the potential energy surfaces obtained by two‐dimensional scans indicates that the one‐step DA reaction that would lead to trans‐fused products also will not occur under conventional reaction conditions.
BBr3‐Assisted Cleavage of Most Ethers Does Not Follow the Commonly Assumed Mechanism
Authors: Sousa Carla , Silva Pedro J. 
Published: May 2013

AbstractDensity‐functional computations were used to probe the reaction mechanism of BBr3‐assisted ether cleavage. After the initial formation of an ether–BBr3 adduct, secondary and tertiary alkyl ethers are cleaved through Br– transfer from the activated BBr3 to the alkyl moiety, as postulated in the literature. In contrast, all other ethers studied react through a novel pathway involving two ether–BBr3 adducts, one of which acts as Br– donor, and the second as the reaction substrate. The identification of the novel bimolecular mechanism for this classical reaction has further applications, because it implies that BBr3‐assisted ether cleavage may become impossible if the ether is surrounded by bulky portions of the molecule that prevent the approach of the attacking BBr3 adduct. Our data also allow the construction of an order of reactivity of alkyl ether deprotection: isopropyl, benzyl, tertiary alkyl, allyl, isobutyl and ethyl can be removed sequentially as their bromo derivatives; phenyl, cyanomethyl and chloromethyl groups can be sequentially removed as their corresponding alcohols.
Perceived system longevity increases system justification and the legitimacy of inequality
Authors: Blanchar John C. , Eidelman Scott 
Published: May 2013

AbstractIn two studies, we test the prediction that perceived longevity increases system justification and the legitimacy of inequality. In Study 1, the foundations of the capitalist system were portrayed as younger or older on a timeline. Participants scored higher on economic system justification and perceived capitalism as more legitimate when they were led to believe that this economic system was older. In Study 2, we manipulated the longevity of the Indian caste system and recruited both Indians and Americans. Both groups judged the caste system as more justifiable and legitimate when it was described as more longstanding. In addition, Indians reported more system dependence and judged the caste system as more justifiable and legitimate than Americans. Feelings of system dependence explained the effects of nationality, but not the effects of longevity, on the justification and legitimacy of the caste system. Perceived longevity is a novel contributor to system justification. Copyright © 2013 John Wiley & Sons, Ltd.