bluuebunny/crossref_metadata_2025_split huggingface dataset:
Activities of Prenylphenol Derivatives from Fruitbodies of Albatrellus spp. on the Human and Rat Vanilloid Receptor 1 (VR1) and Characterisation of the Novel Natural Product, Confluentin
Authors: Hellwig Veronika , Nopper Reilinde , Mauler Frank , Freitag Joachim , Ji‐Kai Liu , Zhi‐Hui Ding , Stadler Marc 
Published: May 2003

AbstractSeveral prenylphenols from basidiocarps of European and Chinese Albatrellus spp., namely grifolin (1), neogrifolin (2), confluentin (3), scutigeral (4), and albaconol (5) were investigated concerning their activities in test models for vanilloid receptor modulation. The isolation of these compounds from A. confluens and structure elucidation of the novel natural product confluentin (3) are described. The effects of scutigeral and neogrifolin on vanilloid receptors were studied by means of electrophysiological methodology on rat dorsal root ganglion neurons as well as on recombinant cell lines expressing the rat VR1 receptor. Concurrently, the effects of compounds 1—5 on a reporter cell line expressing the human vanilloid receptor VR1 were measured. In contrast to previous studies reported in the literature, the results of these investigations suggest that fungal prenylphenols act as weak antagonists (activity in the μM range), rather than exhibiting agonistic activities.
The Structure and Ion Channel Activity of 6‐Benzylamino‐3‐hydroxyhexa‐cyclo[6.5.0.03, 7.04, 12.05, 10.09, 13]tridecane
Authors: Malan Sarel F. , Dyason Karin , Wagenaar Bianca , van der Walt J. Jurgens , Van der Schyf Cornelis J. 
Published: May 2003

AbstractA novel compound, 6‐benzylamino‐3‐hydroxyhexacyclo [6.5.0.03, 7.04, 12.05, 10.09, 13]‐tridecane, was synthesized as part of an ongoing study to explore the ion channel activity of polycyclic cage amines. The known polycyclic calcium channel antagonist, 8‐benzylamino‐8, 11‐oxapentacyclo [5.4.0.02, 6.03, 10.05, 9]undecane (NGP 1‐01) served as the lead compound and as a positive control for channel activity. The title compound inhibited calcium currents at test concentrations of 10 μM at depolarized membrane potentials (in the potential range where the L‐type calcium channel inactivates). At the test concentrations modulating effects were also observed for sodium and the delayed rectifier potassium currents. Due to its activity at both Ca2+ and Na+ channels, this compound may offer utility as a cardiovascular and/or neuroprotecting agent.
Synthesis and Pharmacological Investigations of Some 4‐Hydroxycoumarin Derivatives
Authors: Manolov Ilia , Danchev Nicolay D. 
Published: May 2003

AbstractThe synthesis of ten coumarin derivatives of 4‐hydroxycoumarin and various unsaturated ketones and aldehydes is described. The structures of the synthesized compounds were confirmed by IR, 1H‐NMR, and mass‐spectral data. Acute toxicity studies of the compounds were performed on mice by oral and intraperitoneal administration. A comparative pharmacological study of the in vivo anticoagulant effects of the derivatives with respect to warfarin, showed that the compounds have anticoagulant activity. Compounds 4‐hydroxy‐3‐[1‐phenyl‐2‐(4′‐chlorobenzoyl)ethyl]‐2H‐1‐benzopyran‐2‐one 2b, 4‐hydroxy‐3‐[1‐(4‐fluorophenyl)‐3‐oxobutyl]‐2H‐1‐benzopyran‐2‐one 3a, and 3, 3′‐p‐bromobenzylidene‐bis‐(4‐hydroxy‐2H‐1‐benzopyran‐2‐one) 4b showed slight acute toxicity and a greater anticoagulant effect than warfarin.
Substituted Quinazolines, Part 2. Synthesis and In‐Vitro Anticancer Evaluation of New 2‐Substituted Mercapto‐3H‐quinazoline Analogs
Authors: Khalil Ashraf A. , Hamide Sami G. Abdel , Al‐Obaid Abdulrahman M. , El‐Subbagh Hussein I. 
Published: May 2003

AbstractA new series of 2‐substituted mercapto‐3H‐quinozolines bearing 6‐iodo and 2‐heteroarylthio functions was synthesized and screened for their in vitro antitumor activity. Eighteen compounds were identified as active anticancer agents. N′‐[(3‐Benzyl‐4‐oxo‐6‐iodo‐3H‐quinazoline‐2‐yl)thioacetyl]‐N3‐ethylthiosemicarbazide (10), N‐benzoyl‐N′‐[2‐(3‐benzyl‐4‐oxo‐6‐iodo‐3H‐quinozolin‐2‐yl)thioacetyl]hydrazine (12), and 2‐[(3, 6‐dioxo‐pyridazin‐4‐yl)thio]‐3‐benzyl‐4‐oxo‐6‐iodo‐3H‐quinazoline (20) proved to be the most active members in this study. They showed MG‐MID, GI50 values of 12.8, 11.3, and 13.8 μM, respectively. The detailed synthesis and biological screening data are reported.
A Test for the Number of Coupled Spins I=1/2 in Magic‐Angle‐Spinning Solids: Zero‐Quantum Recoupling of Multiple‐Quantum Coherences
Authors: Hughes Colan E. , Schmedt auf der Günne Jörn , Levitt Malcolm H. 
Published: May 2003

AbstractCurrent methodologies for estimating the number of coupled spins I=1/2 in solids are based upon the maximum multiple‐quantum order that can be observed. This strategy establishes a clear lower bound on the number of coupled spins I=1/2. However, it is difficult to ascertain the exact number of coupled spins, since the absence of a peak could be due either to the limited size of the spin system or to the experimental difficulty of exciting high‐quantum orders and recovering those coherences into detectable signals. Herein, a supplementary test is proposed that allows one to determine whether a given coherence has the highest possible order in the spin system. The sample is subjected to magic‐angle spinning and the behaviour of the coherence under a rotor‐synchronised spin‐echo sequence is compared to its behaviour under a zero‐quantum recoupling sequence. A similar decay of the coherence in these two experiments is strong evidence for the coherence order being the maximum possible. We propose applications to biomolecular solid‐state NMR spectroscopy.
Adsorption of CO2 and Coadsorption of H and CO2 on Potassium‐Promoted Cu(115)
Authors: Onsgaard Jens , Hoffmann Søren V. , Møller Palle , Godowski P. Jan , Wagner Jacob B. , Paolucci Giorgio , Baraldi Alessandro , Comelli Giovanni , Groso Amela 
Published: May 2003

AbstractThe influence of potassium, in the submonolayer regime, on the adsorption and coadsorption of CO2 and H on a stepped copper surface, Cu(115), has been studied by photoelectron spectroscopy, temperature‐programmed desorption, and work‐function measurements. Based on the fast recording of C 1s and O 1s core‐level spectra, the uptake of CO2 on K/Cu(115) surfaces at 120 K has been followed in real time, and the different reaction products have been identified. The K 2p3/2 peak exhibits a chemical shift of −0.4 eV with CO2 saturation, the C 1s peaks of the CO3 and the CO species show shifts of −0.8 and −0.5 eV, respectively, and the C 1s peak of the physisorbed CO2 exhibits no shift. The effects of gradually heating the CO2/K/Cu(115) surface include the desorption of physisorbed CO2 at 143 K; the desorption of CO at 193 K; the ordering of the CO3 species, and subsequently the dissociation of the carbonate with desorption at 520–700 K. Formate, HCOO−, was synthesized by the coadsorption of H and CO2 on the K/Cu(115) surface at 125 K. Formate formed exclusively for potassium coverages of less than 0.4 monolayer, whereas both formate and carbonate were formed at higher coverages. The desorption of formate‐derived CO2 took place in the temperature range 410–425 K and carbonate‐derived CO2 desorbed at 645–660 K, depending on the potassium coverage.
Studies on Intra‐Supramolecular and Intermolecular Electron‐Transfer Processes between Zinc Naphthalocyanine and Imidazole‐Appended Fullerene
Authors: El‐Khouly Mohamed E. , Rogers Lisa M. , Zandler Melvin E. , Suresh Gadde , Fujitsuka Mamoru , Ito Osamu , D'Souza Francis 
Published: May 2003

AbstractSpectroscopic, computational, redox, and photochemical behavior of a self‐assembled donor‐acceptor dyad formed by axial coordination of zinc naphthalocyanine, ZnNc, and fulleropyrrolidine bearing an imidazole coordinating ligand (2‐(4′‐imidazolylphenyl)fulleropyrrolidine, C60Im) was investigated in noncoordinating solvents, toluene and o‐dichlorobenzene, and the results were compared to the intermolecular electron transfer processes in a coordinating solvent, benzonitrile. The optical absorption and ab initio B3 LYP/3–21G(*) computational studies revealed self‐assembled supramolecular 1:1 dyad formation between the ZnNc and C60Im entities. In the optimized structure, the HOMO was found to be entirely located on the ZnNc entity while the LUMO was found to be entirely on the fullerene entity. Cyclic voltammetry studies of the dyad exhibited a total of seven one‐electron redox processes in o‐dichlorobenzene, with 0.1 M tetrabutylammonium perchlorate. The excited‐state electron‐transfer processes were monitored by both optical‐emission and transient‐absorption techniques. Direct evidence for the radical‐ion‐pair (C60Im.−:ZnNc.+) formation was obtained from picosecond transient‐absorption spectral studies, which indicated charge separation from the singlet‐excited ZnNc to the C60Im moiety. The calculated rates of charge separation and charge recombination were 1.4×1010 s−1 and 5.3×107 s−1 in toluene and 8.9×109 s−1 and 9.2×107 s−1 in o‐dichlorobenzene, respectively. In benzonitrile, intermolecular electron transfer from the excited triplet state of ZnNc to C60Im occurs and the second‐order rate constant (kqtriplet) for this quenching process was 5.3×108 M−1 s−1.
Femtochemistry of trans‐Azomethane: A Combined Experimental and Theoretical Study
Authors: Diau Eric W.‐G. , Zewail Ahmed H. 
Published: May 2003

AbstractThe dissociation dynamics of trans‐azomethane upon excitation to the S1(n,π*) state with a total energy of 93 kcal mol−1 is investigated using femtosecond‐resolved mass spectrometry in a molecular beam. The transient signal shows an opposite pump–probe excitation feature for the UV (307 nm) and the visible (615 nm) pulses at the perpendicular polarization in comparison with the signal obtained at the parallel polarization: The one‐photon symmetry‐forbidden process excited by the UV pulse is dominant at the perpendicular polarization, whereas the two‐photon symmetry‐allowed process initiated by the visible pulse prevails at the parallel polarization. At the perpendicular polarization, we found that the two CN bonds of the molecule break in a stepwise manner, that is, the first CN bond breaks in ≈70 fs followed by the second one in ≈100 fs, with the intermediate characterized. At the parallel polarization, the first CN bond cleavage was found to occur in 100 fs with the intensity of the symmetry‐allowed transition being one order of magnitude greater than the intensity of the symmetry‐forbidden transition at the perpendicular polarization. Theoretical calculations using time‐dependent density functional theory (TDDFT) and the complete active space self‐consistent field (CASSCF) method have been carried out to characterize the potential energy surface for the ground state, the low‐lying excited states, and the cationic ground state at various levels of theory. Combining the experimental and theoretical results, we identified the elementary steps in the mechanism: The initial driving force of the ultrafast bond‐breaking process of trans‐azomethane (at the perpendicular polarization) is due to the CNNC torsional motion initiated by the vibronic coupling through an intensity‐borrowing mechanism for the symmetry‐forbidden n–π* transition. Following this torsional motion and the associated molecular symmetry breaking, an S0/S1 conical intersection (CI) can be reached at a torsional angle of 93.1° (predicted at the CASSCF(8,7)/cc‐pVDZ level of theory). Funneling through the S0/S1 CI could activate the asymmetric CN stretching motion, which is the key motion for the consecutive CN bond breakages on the femtosecond time scale.
Quantum Control of Gas‐Phase and Liquid‐Phase Femtochemistry
Authors: Brixner Tobias , Gerber Gustav 
Published: May 2003

AbstractActive control of chemical reactions on a microscopic (molecular) level, that is, the selective breaking or making of chemical bonds, is an old dream. However, conventional control agents used in chemical synthesis are macroscopic variables such as temperature, pressure or concentration, which gives no direct access to the quantum‐mechanical reaction pathway. In quantum control, by contrast, molecular dynamics are guided with specifically designed light fields. Thus it is possible to efficiently and selectively reach user‐defined reaction channels. In the last years, experimental techniques were developed by which many breakthroughs in this field were achieved. Femtosecond laser pulses are manipulated in so‐called pulse shapers to generate electric field profiles which are specifically adapted to a given quantum system and control objective. The search for optimal fields is guided by an automated learning loop, which employs direct feedback from experimental output. Thereby quantum control over gas‐phase as well as liquid‐phase femtochemical processes has become possible. In this review, we first discuss the theoretical and experimental background for many of the recent experiments treated in the literature. Examples from our own research are then used to illustrate several fundamental and practical aspects in gas‐phase as well as liquid‐phase quantum control. Some additional technological applications and developments are also described, such as the automated optimization of the output from commercial femtosecond laser systems, or the control over the polarization state of light on an ultrashort timescale. The increasing number of successful implementations of adaptive learning techniques points at the great versatility of computer‐guided optimization methods. The general approach to active control of light–matter interaction has also applications in many other areas of modern physics and related disciplines.
Cover Picture: Electrosurface Phenomena at Polymer Films for Biosensor Applications (ChemPhysChem 5/2003)
Authors: Zimmermann Ralf , Birkert Oliver , Gauglitz Günter , Werner Carsten 
Published: May 2003

AbstractThe cover picture summarizes the principle of the Microslit Electrokinetic Set‐Up, which has been applied for the combined determination of zeta potential and surface conductivity of polymer films for biosensor applications. The method is based on streaming potential and streaming current measurements across rectangular channels formed by two planar sample carriers (20 mm×10 mm) at varied distances in the range of 1 to 60 μm. Combined determination of zeta potential and surface conductivity was advantageous for the analysis of interfacial charge distributions at swelling and reorganizing solid surfaces. The high sensitivity of the surface conductivity for structural variations of layered substrates may even allow the use of this parameter for detection in future biosensors. Find out more in the article by Zimmermann et al. on pages 509–514.
Promising effects of adenosine triphosphate infusion on nutritional status and quality of life in advanced non‐small‐cell lung cancer: a randomized clinical trial
Authors: Dagnelie Pieter C. , Agteresch Hendrik J. 
Published: May 2003

AbstractPrevious studies animal and phase I/II studies suggested that regular ATP infusions may inhibit loss of body weight in cancer. In this report, we summarize data from a recent trial (Agteresch et al. [2000a] J Natl Cancer Inst 92:321–328; Agteresch et al. [2000b] Eur J Clin Pbarmacol 56:49–55) in 58 patients with non‐small‐cell lung cancer, stage IIIB or IV. Patients were randomized to receive either 10 intravenous 30‐h ATP infusions every 2 to 4 weeks (n=28), or no ATP (n=30). Body weight, body composition (anthropometry, isotope dilution), muscle strength (elbow flexor and knee extensor), energy intake (3‐day food record), and quality of life (validated Rotterdam Symptom Checklist, RSCL) were assessed at 4‐week intervals during 28 weeks. Between‐group differences were tested for statistical significance (P < 0.05) by repeated‐measures analysis of covariance. Over the 28‐week follow‐up period, the control group showed progressive deterioration in body weight, fat mass, body cell mass, arm muscle area, and elbow flexor and knee extensor muscle strength. In contrast, in the ATP group, complete stabilization of these parameters was observed. Energy intake decreased significantly in the control group, but remained stable in the ATP group. ATP also inhibited the progressive rise in plasma values of C‐reactive protein seen in control patients. All mentioned between‐group differences were statistically significant. Significant favorable effects of ATP were also found for different domains of quality of life as assessed by the RSCL, i.e., physical, functional, and overall quality of life, whereas no significant effect of ATP on the psychological subscale of the RSCL was detected. In conclusion, ATP is the first agent that has been shown, in a randomized clinical trial, to counteract the loss of both metabolically active tissues (skeletal muscle and body cell mass) and fat mass, and improve muscle strength and quality of life (including functional status and fatigue) in patients with advanced cancer. Maintenance of energy intake and inhibition of chronic inflammation are likely to contribute to these effects of ATP. These results warrant further studies in patients with cancer and inflammatory diseases. Drug Dev. Res. 59:146–151, 2003. © 2003 Wiley‐Liss, Inc.
Modulation of the A3 adenosine receptor by low agonist concentration induces antitumor and myelostimulatory effects
Authors: Merimsky Ofer , Bar‐Yehuda Sara , Madi Lea , Fishman Pnina 
Published: May 2003

AbstractThe A3 adenosine receptor (A3AR) agonists IB‐MECA and Cl‐IB‐MECA act as anticancer agents by inhibiting the growth of melanoma and colon carcinoma cells both in vitro and in vivo. The A3AR is highly expressed in these tumor cells and upon agonist binding receptor internalization and recycling occurs. The downstream signaling pathways that follow these events include a decrease in the expression level of protein kinase A (PKA) and protein kinase B/Akt (PKB/Akt) leading to the deregulation of the Wnt and the NF‐κB signaling pathways. Interestingly, IB‐MECA and Cl‐IB‐MECA generate the opposite, beneficial effect on myeloid cells. These agonists induce the production of granulocyte colony‐stimulating factor (G‐CSF) by murine splenocytes. The molecular mechanisms underlying the events prior to G‐CSF production include the upregulation of NF‐κB and the upstream kinases phosphoinositide 3‐kinase (PI3K), PKB/Akt, and IKK. In addition, a myeloprotective effect is noted upon administration of IB‐MECA and Cl‐IB‐MECA to chemotherapy‐treated mice. This was expressed by accelerated recovery of white blood cells and neutrophil counts in cyclophosphamide‐treated mice following agonist administration. Taken together, activation of the A3AR on tumor and normal cells generates opposing responses: in tumor cells, NF‐κB expression level decreases, resulting in tumor growth inhibition, while in normal cells it is upregulated, leading to G‐CSF production and the induction of myelostimulation. It thus appears that A3AR agonists act as tumor growth inhibitors, simultaneously maintaining the myeloid system, capable of preventing the damage of chemotherapeutic agents. Drug Dev. Res. 58:386–389, 2003. © 2003 Wiley‐Liss, Inc.
Effects of adenosine on prostate adenocarcinoma PC‐3 and bladder carcinoma J82 cell lines
Authors: Nucciarelli Fabio , Mearini Ettore , Minelli Alba 
Published: May 2003

AbstractProstate adenocarcinoma PC‐3 and bladder carcinoma J82 cell lines were used to investigate the role of adenosine in the modulation of cell growth. Our results show that adenosine inhibited cell proliferation in both cell lines and markedly induced apoptosis only in J82 cells. PC‐3 and J82 cells showed typical sigmoid growth curves. Only the J82 growth curve was modified by the addition of adenosine deaminase, indicating that this cell line is sensitive to the presence of endogenous extracellular adenosine. Exogenous extracellular adenosine induced a dose‐dependent decrease of cell growth in both cell lines. 2′‐Deoxyadenosine and dipyridamole were used to investigate whether the growth inhibitory effect of adenosine was related to cellular uptake or to receptor‐mediated action. Our results show that 2′‐deoxyadenosine was a less effective inhibitor for J82 than PC‐3 cells. Dipyridamole reduced the inhibitory effect of adenosine in both cell lines. The determination of viability associated with Hoechst staining showed that adenosine clearly induced apoptosis in J82 cell lines but was less effective in PC‐3 cell lines. In conclusion, we have shown that the growth of prostate adenocarcinoma PC‐3 and bladder carcinoma J82 cell lines is inhibited by adenosine and that adenosine is capable of inducing apoptosis, although to a different extent in both cell lines. Drug Dev. Res. 58:390–395, 2003. © 2003 Wiley‐Liss, Inc.
Adenosine downregulates cytokine‐induced expression of intercellular adhesion molecule‐1 on rheumatoid synovial fibroblasts independently of adenosine receptor signaling
Authors: Nakazawa Takashi , Koshiba Masahiro , Kosaka Hidekazu , Tsuji Goh , Nakamachi Yuji , Saura Ryuichi , Kurosaka Masahiro , Tanaka Yoshiya , Kumagai Shunichi 
Published: May 2003

AbstractAdhesion of fibroblast‐like synoviocytes (FLSs) to T cells through the interaction of lymphocyte function‐associated antigen‐1 (LFA‐1) and intercellular adhesion molecule‐1 (ICAM‐1) plays a pivotal role in the pathogenesis of rheumatoid arthritis (RA). We therefore used flow cytometry and quantitative polymerase chain reaction (PCR) to examine the effect of adenosine and its derivatives on expression of ICAM‐1 induced by tumor necrosis factor‐alpha and interferon‐gamma in primary rheumatoid FLSs (RA‐FLSs) and E11 cells, an RA‐FLS line. Exposing cells to adenosine (5–500 µM) for 24 h in the presence of coformycin, an adenosine deaminase inhibitor, concentration‐dependently inhibited cytokine‐induced transcription of ICAM‐1 mRNA, as well as subsequent surface expression of the protein. Although transcription of all four adenosine receptor isoforms has been detected in FLSs, neither the A1 receptor agonist R‐PIA, the A2A receptor agonist CGS21680 nor the A3 agonist Cl‐IB‐MECA had any effect on cytokine‐induced ICAM‐1 expression. Conversely, A1/A2 receptor antagonist xanthine amine congener and A2A antagonist ZM240385 both failed to suppress the effect of adenosine. Adenosine appears to inhibit cytokine‐induced ICAM‐1 expression in FLSs independently of adenosine receptor‐mediated signaling. By contrast, the effect of adenosine was neutralized by nitrobenzylmercaptopurin, a nucleoside transporter inhibitor, or by ABT702, an adenosine kinase inhibitor. This suggests that adenosine taken up via the nucleoside transporter is phosphorylated by adenosine kinase, and the resultant phospho‐adenosine interferes with the ICAM‐1 transcription and cell surface expression. Downregulation of T cell–FLS interaction by adenosine may thus represent a novel approach to the treatment of RA. Drug Dev. Res. 58:368–376, 2003. © 2003 Wiley‐Liss, Inc.