bluuebunny/crossref_metadata_2025_split huggingface dataset:
Identification and quantification of two antihepatotoxic coumarinolignoids cleomiscosin A and cleomiscosin B in the seeds of Cleome viscosa using liquid chromatography–tandem mass spectrometry
Authors: Chattopadhyay Sunil K. , Kumar Satyanshu , Kaur Ranjeet , Tandon Sudeep , Rane Shailendra 
Published: September 2008

AbstractA sensitive liquid chromatography/electrospray ionization tandem mass spectrometric (LC/ESI‐MS/MS) method was developed for the identification and quantification of two antihepatotoxic coumarinolignoids cleomiscosin A and cleomiscosin B in different extracts of the seeds of Cleome viscosa. The separation of cleomiscosin A and cleomiscosin B was achieved on an RP18 column using a solvent system consisting of a mixture of acetonitrile–methanol (1:2, v/v) and acetonitrile–water–formic acid (5:95:0.3, v/v) as a mobile phase in a gradient elution mode. A multiple‐reaction monitoring (MRM) method was developed for quantification of cleomiscosin A and cleomiscosin B in the seed extracts of Cleome viscosa. On the basis of signal‐to‐noise ratio of 3, the limit of detection in MRM mode for cleomiscosin A and cleomiscosin B were 1.0 and 4.0 ng/mL respectively. The method was validated in terms of linearity, accuracy and precision for 6 days. The method developed was found to be useful for identification and quantification of cleomiscosin A and cleomiscosin B in the different extracts of the seeds of Cleome viscosa. Copyright © 2008 John Wiley & Sons, Ltd.
Liver glycogen metabolism during short‐term insulin‐induced hypoglycemia in fed rats
Authors: Obici Simoni , Lopes‐Bertolini Gisele , Curi Rui , Bazotte Roberto Barbosa 
Published: September 2008

AbstractThe activities of glycogen phosphorylase and synthase during infusions of glucagon, isoproterenol, or cyanide in isolated liver of fed rats submitted to short‐term insulin‐induced hypoglycemia (IIH) was investigated. A condition of hyperinsulinemia/hypoglycemia was obtained with an intraperitoneal injection of regular insulin (1.0 U kg−1). The control group received ip saline. The experiments were carried out 60 min after insulin (IIH group) or saline (COG group) injection. The rats were anesthetized and after laparotomy, blood was collected from the vena cava for glucose and insulin measurements. The liver was then infused with glucagon (1 nM), isoproterenol (2 µM), or cyanide (0.5 mM) during 20 min and a sample of the organ was collected for determination of the activities of glycogen phosphorylase and synthase 5 min after starting and 10 min after stopping the infusions. The infusions of cyanide, glucagons, and isoproterenol did not change the activities of glycogen synthase and glycogen phosphorylase. However, glycogen catabolism was decreased during the infusions of glucagon and isoproterenol in IIH rats, being more intense with isoproterenol (p < 0.05), than glucagon. It was concluded that short‐term IIH promoted changes in the liver responsiveness of glycogen degradation induced by glucagon and isoproterenol without a change in the activities of glycogen phosphorylase and synthase. Copyright © 2008 John Wiley & Sons, Ltd.
Theoretical Insights into Enantioselective Catalysis: The Mechanism of the Kharasch–Sosnovsky Reaction
Authors: Mayoral José Antonio , Rodríguez‐Rodríguez Sergio , Salvatella Luis 
Published: September 2008

AbstractThe mechanism of the Kharasch–Sosnovsky reaction has been investigated using B3 LYP/6‐31G* calculations on a chiral reaction model [cyclohexene + tert‐butyl perbenzoate → cyclohex‐2‐enyl benzoate + tert‐butyl alcohol, catalyzed by a chiral bisoxazoline‐copper(I) complex]. Although two previous reaction mechanisms have been considered, the results are consistent with a new mechanistic pathway. This path involves ligand exchange between the catalyst–cyclohexene complex with tert‐butyl perbenzoate to give a catalyst–perester complex, which undergoes an (either one‐ or two‐step) oxidative addition reaction to yield a copper(III) complex. The limiting step of the Kharasch–Sosnovsky reaction consists of an intramolecular step involving the abstraction of an allylic hydrogen from cyclohexene [which is π‐bound to the copper(III) complex]. The resulting allyl‐copper(III) complex (subsequent to the loss of tert‐butanol) can undergo a haptotropic rearrangement by means of an η1‐allyl/η3‐allyl equilibrium, leading to scrambling between vinylic and allylic positions when an isotopically labeled substrate is used. The allyl‐copper(III) ion undergoes a stereospecific reductive elimination involving the π‐bond migration to yield a reaction product–catalyst complex, which can regenerate the alkene‐copper(I) complex by ligand exchange. The proposed reaction mechanism is consistent with all known experimental results (including enantioselectivity data).
Aldol Reactions between L‐Erythrulose Derivatives and Chiral α‐Amino and α‐Fluoro Aldehydes: Competition between Felkin–Anh and Cornforth Transition States
Authors: Díaz‐Oltra Santiago , Carda Miguel , Murga Juan , Falomir Eva , Marco J. Alberto 
Published: September 2008

AbstractBoth matched and mismatched diastereoselection have been observed in aldol reactions of a boron enolate of a protected L‐erythrulose derivative with several chiral α‐fluoro and α‐amino aldehydes. Strict adherence to the Felkin–Anh model for the respective transition structures does not account satisfactorily for all the observed results, as previously observed in the case of α‐oxygenated aldehydes. In some cases, only the Cornforth model provides a good explanation. The factors that influence this dichotomy are discussed and a general mechanistic model is proposed for aldol reactions with α‐heteroatom‐substituted aldehydes. Additional support for the model was obtained from density functional calculations.
Interferon‐α for recurrent World Health Organization grade 1 intracranial meningiomas
Authors: Chamberlain Marc C. , Glantz Michael J. 
Published: September 2008

AbstractBACKGROUND.Intracranial meningiomas are common, they frequently recur after surgery or radiotherapy, and there are limited data regarding the treatment of intracranial meningiomas with chemotherapy. A phase 2 study was designed to estimate the 6‐month progression‐free survival of patients with recurrent, treatment‐refractory, World Health Organization grade 1 meningiomas who were treated with interferon‐α.METHODS.Thirty‐five patients with recurrent meningiomas ranging in age from 36 years to 88 years (median age, 61 years) were treated according to a prospective phase 2 study. All patients had received prior surgery, radiotherapy, (involved‐field radiotherapy in 35 patients andstereotactic radiotherapy in 22 patients), and chemotherapy (hydroxyurea in 19 patients and other in 17 patients). On radiographic documentation of progressive disease, interferon‐α (at a dose of 10 million U/m2 administered subcutaneously every other day) was initiated. A complete blood count and chemistry panel was obtained before every cycle, and cranial magnetic resonance images were obtained every 3 months.RESULTS.The most common grade 3 and 4 toxicities were fatigue (6 patients; 17%), anemia (3 patients; 8.6%), and leukopenia (3 patients; 8.6%) (toxicities were graded according to the National Cancer Institute's Common Toxicity Criteria [version 3.0]). Three patients went off study because of toxicity, and 7 patients required a dose reduction. There were no treatment‐related deaths or delays in therapy reported. All patients were assessable for response. No patient demonstrated a neuroradiographic complete or partial response. Twenty‐six patients demonstrated stable disease after the first 3 cycles of interferon‐α, and 9 patients had progressive disease. The progression‐free survival rate was 54% at 6 months and 31% at 12 months. The median time to tumor progression was 7 months (range, 2‐24 months). The median survival was 8 months (range, 3‐28 months).CONCLUSIONS.Treatment with interferon‐α for recurrent meningiomas was found to be tolerated moderately well and was modestly effective. Cancer 2008. © 2008 American Cancer Society.
Clofarabine combinations as acute myeloid leukemia salvage therapy
Authors: Faderl Stefan , Ferrajoli Alessandra , Wierda William , Huang Xuelin , Verstovsek Srdan , Ravandi Farhad , Estrov Zeev , Borthakur Gautam , Kwari Monica , Kantarjian Hagop M. 
Published: September 2008

AbstractBACKGROUND.Outcome of patients with relapsed acute myeloid leukemia (AML) remains unsatisfactory. Clofarabine is a nucleoside analog with activity in adult AML. Combinations with cytarabine in AML are feasible and effective. Idarubicin is another active AML drug, which has not yet been tested with clofarabine.METHODS.The authors therefore designed a phase I study of clofarabine ± cytarabine, plus idarubicin. Patients with primary refractory or first‐relapse AML were assigned to either clofarabine plus idarubicin (CI) if previously exposed to cytarabine with a response lasting <12 months, or clofarabine and idarubicin plus cytarabine (CIA) for responses ≥12 months, or if never exposed to cytarabine. A standard “3 + 3” phase 1 design was followed to define maximum tolerated dose (MTD). Forty‐four patients were treated (23 CI; 21 CIA).RESULTS.Dose‐limiting toxicities were hyperbilirubinemia and hepatic transaminase elevations for CI‐treated patients in addition to mucositis and diarrhea for CIA‐treated patients. MTD for CI was clofarabine 22.5 mg/m2 intravenously daily × 5 and idarubicin 10 mg/m2 intravenously daily × 3. MTD for CIA was clofarabine 22.5 mg/m2 intravenously × 5, idarubicin 6 mg/m2 intravenously × 3, and cytarabine 0.75 g/m2 intravenously × 5 days.CONCLUSIONS.A phase 2 randomized trial is in process to compare activity between treatment arms. Cancer 2008. © 2008 American Cancer Society.
A discrete geometric conservation law (DGCL) for a cell vertex finite‐volume algorithm on moving domains
Authors: Gil A. J. , Bonet J. , Silla J. , Hassan O. 
Published: September 2008

AbstractThis paper revisits the classical discrete geometric conservation law for the arbitrary Lagrangian–Eulerian conservation equations in a moving domain when the conservation laws are mapped to a fixed reference domain. The discretized form of the equations is formulated by means of a cell vertex finite‐volume algorithm with special emphasis on the implications of the discrete time–space algorithm for the preservation of free‐stream flows. Under these circumstances, two corrections are introduced in order to guarantee the preservation of a free‐stream flow evolving in time. A time correction is required to resolve the integration errors in the Jacobian of the transformation or mapping between fixed referential and current domains. A spatial correction is also needed to account for the inexact surface integration in the faces of the dual mesh. Copyright © 2008 John Wiley & Sons, Ltd.
Sulfate‐Bridged Dimeric Copper(II) Complexes with Three‐Dimensional Network: Synthesis, Structure and DFT Studies
Authors: Basu Chandrama , Biswas Saptashati , Chattopadhyay Asoke P. , Stoeckli‐Evans Helen , Mukherjee Soma 
Published: September 2008

AbstractThe 1:1 reaction of the diacetyl monoxime‐2‐pyridyl hydrazone HL1 (1) and the pyridine‐2‐carboxaldehyde‐2‐imidazoline hydrazone hydrobromide HL2 (2) with copper(II) sulfate pentahydrate in methanol affords a series of new sulfate‐bridged dimeric copper(II) complexes, [CuII2(HL1)2(μ‐SO4)2]·4H2O (1a) and [CuII2(HL2)2(μ‐SO4)Br2]·2H2O (2a), respectively. The room temperature magnetic moments of the complexes 1a and 2a are 1.82 μβ and 1.84 μβ, respectively. The bands appearing in the UV region (200–340 nm) are characteristic of the ligands HL1 (1) and HL2 (2). In complexes 1a and 2a, these ligand centred bands are accompanied by multiple bands extending into the visible region (370–480 nm). The association constant (Kass, UV/Vis) was found to be (1.120 ± 0.002) × 105 for 1a and (1.196 ± 0.002) × 104 for 2a at 298 K determined using UV/Vis spectroscopy. On excitation at 285 nm, ligand 1 emits strongly in the 364 nm region due to an intraligand 1(π–π*) transition. Upon complexation with copper(II), the emission peak is slightly blue shifted (354 nm, F/Fo 0.89) with a little quenching in the emission intensity as expected for divalent copper. Complexes 1a and 2a exhibit two consecutive oxidation couples for two copper(II) centres in deionised distilled water under a nitrogen atmosphere. DFT and TDDFT calculations were performed and the results are highly consistent with the spectroscopic behaviour of the complexes. The molecular structures of dinuclear 1a (Cu···Cu 4.555 Å) and 2a (Cu···Cu 6.106 Å) have been determined by single‐crystal X‐ray diffraction studies.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Photoreversible Zn2+ Ion Transportation Across an Interface Using Ion‐Chelating Substituted Photochromic 3,3′‐Indolospirobenzopyrans: Steric and Electronic Controlling Effects
Authors: Roxburgh Craig J. , Sammes Peter G. , Abdullah Ayse 
Published: September 2008

AbstractThe photoreversible transportation of Zn2+ ions across an interface using photochromic substituted‐spirobenzopyrans has been demonstrated. The inclusion of strategically placed sterically influencing 3′‐methyl‐3b and 3‐spirocyclohexyl‐3c groupings is investigated and compared to the unsubstituted analogue 3a. Significant control over the spiropyran ring‐opening↔closing reaction, and hence Zn2+ ion transportation has been realised. Additionally, the spiropyran ring‐opening↔closing reactions of two skeletally identical spirobenzopyrans 4 and 5, but possessing “electronically‐modifying” 5‐trifluoromethyl‐substitutents have been studied by 1H NMR spectroscopy: this has enabled us to realise the additional biasing, on the ring‐opening↔closing process, excerpted on these systems through both selectively placed, inductively controlling functional‐group substitution and/or, simultaneously, sterically influencing group substitution. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Isomeric Al2R4, Mg2R2 Species and Oligomerisation Products: Investigation of Al–Al and Mg–Mg σ Bonding
Authors: Pankewitz Tobias , Klopper Wim , Henke Patrick , Schnöckel Hansgeorg 
Published: September 2008

AbstractInitiated by ongoing experimental work in the field of subvalent aluminium compounds and by recent results on isoelectronic Mg2R2 (s1 states) species, detailed theoretical work was necessary to explain the unusual bonding situation in some Al2R4 isomers (R = PtBu2), of a dimeric Al4R′8 (R′ = OtBu) as well as of subhalides Al2F4, Al2Cl4, Mg2Cl2 and some of their oligomers. These results are presented in this contribution. Especially the different isomers of the four‐membered heterocyclic RAlR2AlR molecule needed careful theoretical investigation, since on the way from monomeric AlR2 radicals to the most stable RAlR2AlR isomer with a butterfly shape, intermediates with different Al–Al interactions – exhibiting diradical as well as diradicaloid character – have to be considered. The presented results on the unusual bonding in these AlP2Al four‐membered heterocyclic systems are an important contribution to a better understanding of the bonding situations in many inorganic molecules containing, for example, B2P2, C2P2, Ge2N2, Sn2N2 and Si4 entities, which recently have drawn considerable interest. In analogy to the AlII compounds some isoelectronic MgI species have been investigated. Regarding the obtained results, special attention is drawn to MgCl oligomers, since we found unexpectedly high oligomerisation energies in our calculations. This high stabilisation is based on direct Mg–Mg bonding as well as on Mg–Cl–Mg bridging bonds. These mixed bonding motifs may also be present in the so far unknown solid MgCl. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Grecoketides A and B: New Naphthoquinones from Streptomyces sp. Acta 1362
Authors: Paululat Thomas , Katsifas Efstathios A. , Karagouni Amalia D. , Fiedler Hans‐Peter 
Published: September 2008

AbstractTwo novel naphthoquinones were produced by the streptomycete Acta 1362. It was determined by HPLC/diode‐array screening that freshly isolated actinomycete strains from selected European ecosystems produce new compounds. Grecoketides A and B were isolated and their structures determined. Both compounds have the same aglycon grecoketidone with a sugar side‐chain that differs in one of the two attached sugar units. Moreover, the biosynthesis of grecoketidone was studied by feeding singly and fully labelled acetate. The hexaketide formed is cyclized after s‐mode folding. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Boron‐Based Diastereomerism and Enantiomerism in Imine Complexes – Determination of the Absolute Configuration at Boron by CD Spectroscopy
Authors: Braun Manfred , Schlecht Sebastian , Engelmann Marco , Frank Walter , Grimme Stefan 
Published: September 2008

AbstractBoron turns out to be a stable stereogenic center in imine complexes of aryl and alkyl boronates. Diastereomerically pure complexes 7a–c are obtained from chiral imine ligands 5a,b that are derived from the amino alcohol (R)‐4. The configuration at the boron atom is determined by crystal structure analyses. Racemic boronates 10a–c, available from a condensation of aryl boronic acids 6 with the achiral imine ligand 9, can be separated into stable enantiomers by HPLC on a chiral column. The racemization barrier ΔG≠ has been determined to amount to 105–115 kJ mol–1. The comparison of calculated and measured CD spectra permits to assign unambiguously the absolute configuration to boron in the enantiomeric boronate‐imine complex 10a.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
K‐ras cancer gene mutations in lung tumors from female Swiss (CD‐1) mice exposed transplacentally to 3′‐azido‐3′‐deoxythymidine
Authors: Koujitani Takatoshi , Ton Tai‐Vu T. , Lahousse Stephanie A. , Hong Hue‐Hua L. , Wakamatsu Nobuko , Sills Robert C. 
Published: September 2008

AbstractA transplacental carcinogenicity study was conducted by exposing pregnant Swiss (CD‐1) mice to 0, 50, 100, 200, or 300 mg 3′‐azido‐3′‐deoxythymidine (AZT)/kg body weight (BW) daily for the duration of gestation (18–19 days) [National Toxicology Program,2006]. The incidence of alveolar/bronchiolar adenomas and carcinomas in the 200 and 300 mg/kg groups was significantly higher (P = 0.027 and 0.007, respectively) in male offspring, but not in females (P = 0.338 and 0.315, respectively). The purpose of the present study was to evaluate K‐ras mutation status in lung tumors from the female offspring in AZT exposed groups and to determine whether at the molecular level there were signature K‐ras mutations in lung tumors that were different from spontaneous tumors. K‐ras mutation was detected by cycle sequencing of polymerase chain reaction (PCR)‐amplified DNA, isolated from formalin‐fixed, paraffin‐embedded lung tumors. K‐ras mutations were detected in 17 of 28 (61%) lung tumors from the female offspring in AZT exposed groups. No K‐ras mutations were detected in the 8 tumors examined from the female control group. The predominant mutations were Codon 12 G→T transversions in the 50, 100, and 300 mg/kg groups, and Codon 12 G→C transversions in the 200 and 300 mg/kg groups. K‐ras Codon 12 G→T transversions (TGT mutations) may be induced by oxidative DNA damage and 8‐oxoguanine (8‐oxoG), while K‐ras Codon 12 G→C transversions (CGT mutations) may be due to further oxidative lesions of guanine and 8‐oxoG. Environ. Mol. Mutagen., 2008. Published 2008 Wiley‐Liss, Inc.
Induction of hypothermic conditions associated with increased micronuclei formation in sigma‐1 receptor knockout mice after administration of the antipsychotic compound E‐5842
Authors: Guzmán Antonio , Marín Ana‐Paz , García Concepción , de Henestrosa Antonio R. Fernández , Ruiz María Teresa , Tortajada Araceli , Marcos Ricard 
Published: September 2008

AbstractThe antipsychotic sigma‐1 (σ1) receptor ligand E‐5842 has been shown to increase micronucleated polychromatic erythrocyte (MNPCE) frequency in mouse bone marrow secondary to compound‐induced hypothermia. Interaction with σ1receptor has been considered a plausible contributing factor for E‐5842‐induced hypothermia, raising concern for a possible class effect of sigma receptor ligands in the mouse micronucleus (MN) test. We assessed the potential of E‐5842 (200 mg/kg, oral) to produce hypothermic conditions associated with increased micronuclei formation in σ1receptor knockout (σ1R‐KO) and wild type (WT) mice. After administration, animal's rectal temperature was recorded and peripheral blood and bone marrow samples were obtained (48 hr) and assessed for induction of micronucleated reticulocytes (MNRET) and MNPCE, respectively. E‐5842 administration produced marked hypothermia both in σ1R‐KO and WT mice. Maximum decreases from preadministration temperature were 12.2 and 13.5°C in σ1R‐KO and WT mice, respectively. Temperature returned to normal approximately 32 hr after administration. Bone marrow examination revealed a statistical significant increase (P< 0.05) in MNPCE frequency both in σ1R‐KO and WT animals. Examination of peripheral blood samples showed a slight, although nonstatistical significant, increase in MNRET frequency in σ1R‐KO mice. No similar effect was observed among WT animals. The results obtained after E‐5842 administration to σ1R‐KO mice indicate that induction of hypothermic conditions associated with increased MNPCE formation is not mediated by compound interaction with σ1receptor, ruling out concern for a possible class effect of similar high affinity σ1receptor ligands in the mouse MN test. Environ. Mol. Mutagen., 2008. © 2008 Wiley‐Liss, Inc.
Kinetics of γ‐H2AX focus formation upon treatment of cells with UV light and alkylating agents
Authors: Staszewski Ori , Nikolova Teodora , Kaina Bernd 
Published: September 2008

AbstractHistone H2AX is rapidly phosphorylated in response to DNA double‐strand breaks (DSBs) induced by ionizing radiation (IR). Here we show that DNA damage induced by alkylating agents [methyl methanesulfonate (MMS) and N‐methyl‐N′‐nitro‐N‐nitrosoguanidine (MNNG)] and ultraviolet light (UV‐C) leads to a dose and time dependent accumulation of phosphorylated H2AX (γ‐H2AX). Time course experiments revealed that the number of γ‐H2AX foci reached peak levels 8 hr after MMS or MNNG treatment and declined to almost control values within 24 hr after exposure. Upon UV‐C treatment, a biphasic response was observed with a maximum 12 hr after treatment. In 43‐3B cells deficient in nucleotide excision repair (NER) the number of γ‐H2AX foci increased steadily. γ‐H2AX foci were preferentially formed in BrdU labeled cells. In proliferation compromised cells, the γ‐H2AX level was significantly reduced, indicating that most of the γ‐H2AX foci induced by UV‐C and alkylating agent treatments were replication dependent. The data are in line with the view that DNA damage induced by UV‐C light and simple alkylating agents, leads to the formation of DSBs during DNA replication giving rise to H2AX phosphorylation. In replicating NER defective cells, DSBs accumulate due to nonrepaired primary DNA lesions that produce a high level of DSBs during replication. The data support that γ‐H2AX foci are a useful marker of DSBs that are induced by S‐phase dependent genotoxins during replication. Environ. Mol. Mutagen., 2008. © 2008 Wiley‐Liss, Inc.