bluuebunny/crossref_metadata_2025_split huggingface dataset:
Phytochemical and Biological Studies of Abies Species
Authors: Yang Xian‐Wen , Li Su‐Mei , Shen Yun‐Heng , Zhang Wei‐Dong 
Published: January 2008

AbstractIn the present review, the literature data on the phytochemical and biological investigations on the genus of Abies are summarized with 110 references. Up to now, 277 compounds were isolated from 19 plants of Abies species. The chemical constituents are mostly terpenoids, flavonoids, and lignans, together with minor constituents of phenols, steroids, and others. The crude extracts and metabolites have been found to possess various bioactivities including insect juvenile hormone, antitumor, antimicrobial, anti‐ulcerogenic, anti‐inflammatory, antihypertensive, antitussive, and CNS (central nervous system) activities.
Synthesis, Spectroscopy, and Biological Properties of Vanadium(IV)–Hydrazide Complexes
Authors: Ashiq Uzma , Ara Rifat , Mahroof‐Tahir Mohammad , Maqsood Zahida T. , Khan Khalid M. , Khan Shamsun N. , Siddiqui Hina , Choudhary Muhammad I. 
Published: January 2008

AbstractThe synthesis, spectroscopic, enzyme‐inhibition, and free‐radical‐scavenging properties of a series of vanadium(IV) complexes, compounds 1–10, were investigated. These complexes exhibit a dimeric structure with hydrazide ligands coordinated in a bidentate fashion. All complexes are stable in the solid state, but exhibit varying degrees of stability in solution. In coordinating solvent such as DMSO, stepwise binding of two solvent molecules at the 6th positions trans to the VO bond of the dimeric unit is observed. The dimeric compounds are converted to monomeric species in which both solvent molecules and the hydrazide ligands are coordinated to the VIV center. The free hydrazide ligands 11–20 were inactive against α‐glucosidase, but the VIV complexes showed varying degrees of inhibition, depending on the type of ligand. The DPPH‐radical‐scavenging activities of 1–20 were determined, which indicated that steric and/or electronic effects responsible for changes in geometry play important roles in terms of antioxidant potential.
Isolation, Structure Elucidation, and Antimycobacterial Properties of Dimeric Naphtho‐γ‐pyrones from the Marine‐Derived Fungus Aspergillus carbonarius
Authors: Zhang Yapeng , Ling Sun , Fang Yuchun , Zhu Tianjiao , Gu Qianqun , Zhu Wei‐Ming 
Published: January 2008

AbstractTwo new dimeric naphtho‐γ‐pyrones, compounds 1 and 2, were isolated from the AcOEt extract of the fungal strain WZ‐4‐11 of Aspergillus carbonarius, together with eight known analogues, including 10,10′‐bifonsecin B (3), 6′‐O‐demethylnigerone (4), nigerone (5), isonigerone (6), fonsecin (7), rubrofusarin B (8), TMC 256A1 (9), and flavasperone (10). Their structures were elucidated by means of UV, CD, IR, and 1D‐ and 2D‐NMR spectroscopy, in combination with HR‐MS analysis. The fully assigned 1H‐ and 13C‐NMR data of 3, and the 13C‐NMR data of 6 are reported for the first time. Compounds 1 and 2 showed weak antimycobacterial activities against Mycobacterium tuberculosis H37Rv, with MIC values of 43.0 and 21.5 μM, resp.
Highly Effective Acyclic Carbohydrate Receptors Consisting of Aminopyridine, Imidazole, and Indole Recognition Units
Authors: Mazik Monika , Kuschel Matthias 
Published: January 2008

AbstractNeutral imidazole/aminopyridine‐ and indole/aminopyridine‐based receptors, 1 and 2, have been established as highly effective and selective carbohydrate receptors. These receptors effectively recognise neutral carbohydrates through multiple interactions, including neutral hydrogen bonds and CH⋅⋅⋅π interactions between the sugar CH groups and the aromatic rings of the receptors. The design of these receptors was inspired by the binding motifs observed in the crystal structures of protein–carbohydrate complexes. The formation of very strong complexes with β‐glucopyranoside 5, β‐maltoside 8, and α‐maltoside 9 in organic media has been characterised by 1H NMR spectroscopy and confirmed by a second, independent technique, namely fluorescence spectroscopy. The syntheses, molecular‐modelling studies, binding properties of the receptors 1 and 2 toward selected mono‐ and disaccharides as well as comparative binding studies with receptors 3 and 4 are described.
Electron Exchange in Conformationally Restricted Donor–Spacer–Acceptor Dyads: Angle Dependence and Involvement of Upper‐Lying Excited States
Authors: Benniston Andrew C. , Harriman Anthony , Li Peiyi , Patel Pritesh V. , Sams Craig A. 
Published: January 2008

AbstractThe rate constant for triplet energy transfer (kTET) has been measured in fluid solution for a series of mixed‐metal Ru–Os bis(2,2′:6′,2′′‐terpyridine) complexes built around a tethered biphenyl‐based spacer group. The length of the tether controls the central torsion angle for the spacer, which can be varied systematically from 37 to 130°. At low temperature, but still in fluid solution, the spacer adopts the lowest‐energy conformation and kTET shows a clear correlation with the torsion angle. A similar relationship holds for the inverse quantum yield for emission from the Ru–terpy donor. Triplet energy transfer is more strongly activated at higher temperature and the kinetic data require analysis in terms of two separate processes. The more weakly activated step involves electron exchange from the first‐excited triplet state on the Ru–terpy donor and the size of the activation barrier matches well with that calculated from spectroscopic properties. The pre‐exponential factor derived for this process correlates remarkably well with the torsion angle and there is a large disparity in electronic coupling through π and σ orbitals on the spacer. The more strongly activated step is attributed to electron exchange from an upper‐lying triplet state localized on the Ru–terpy donor. Here, the pre‐exponential factor is larger but shows the same dependence on the geometry of the spacer. Strangely, the difference in coupling through π and σ orbitals is much less pronounced. Despite internal flexibility around the spacer, kTET shows a marked dependence on the torsion angle computed for the lowest‐energy conformation.
Covalent Tethering of Organic Functionality to the Surface of Glassy Carbon Electrodes by Using Electrochemical and Solid‐Phase Synthesis Methodologies
Authors: Chrétien Jean‐Mathieu , Ghanem Mohamed A. , Bartlett Philip N. , Kilburn Jeremy D. 
Published: January 2008

AbstractOrganic linkers such as (N‐Boc‐aminomethyl)phenyl (BocNHCH2C6H4) and N‐Boc‐ethylenediamine (Boc‐EDA) have been covalently tethered onto a glassy carbon surface by employing electrochemical reduction of BocNHCH2C6H4 diazonium salt or oxidation of Boc‐EDA. After removal of the Boc group, anthraquinone as a redox model was attached to the linker by a solid‐phase coupling reaction. Grafting of anthraquinone to electrodes bearing a second spacer such as 4‐(N‐Boc‐aminomethyl)benzoic acid or N‐Boc‐β‐alanine was also performed by following this methodology. The surface coverage, stability and electron transfer to/from the tethered anthraquinone redox group through the linkers were investigated by cyclic voltammetry. The effects of pH and scan rate were studied, and the electron‐transfer coefficient and rate constant were determined by using Laviron's equation for the different types of linker. The combination of electrochemical attachment of protected linkers and subsequent modifications under the conditions of solid‐phase synthesis provides a very versatile methodology for tailoring a wide range of organic functional arrangements on a glassy carbon surface.
Switchable Antenna: A Star‐Shaped Ruthenium/Osmium Tetranuclear Complex with Azobis(bipyridine) Bridging Ligands
Authors: Otsuki Joe , Imai Arata , Sato Katsuhiko , Li Dong‐Mei , Hosoda Mayumi , Owa Masao , Akasaka Tetsuo , Yoshikawa Isao , Araki Koji , Suenobu Tomoyoshi , Fukuzumi Shunichi 
Published: January 2008

AbstractA star‐shaped Ru/Os tetranuclear complex, in which a central Os unit is linked to three peripheral Ru units by 4,4′′‐azobis(2,2′‐bipyridine) (azobpy) bridging ligands, was prepared to examine the unique photodynamics regulated by its redox state. The Ru/Os tetranuclear complex exhibits Ru‐based luminescence at 77 K, whereas the three‐electron reduction (one for each azobpy) of the Ru/Os complex results in luminescence from the Os unit. The photoexcited state of the Ru/Os complex rapidly decays into low energy metal‐to‐ligand charge‐transfer states, in which the excited electron is localized in the azobpy ligand in the form of azobpy.−. Upon the one‐electron reduction of the azobpy ligands, the above‐mentioned low‐energy states become unavailable to the photoexcited complex. As a result, an energy transfer from the Ru‐based excited state to the Os‐based excited state becomes possible. Ultrafast transient absorption measurements revealed that the energy transfer process consists of two steps; intramolecular electron transfer from the terminal bipyridine ligand (bpy.−) to form azobpy2− followed by a metal‐to‐metal electron transfer. Thus, the Ru/Os tetranuclear complex collects light energy into the central Os unit depending on the redox state of the bridging ligands, qualifying as a switchable antenna.
Axoneme‐dependent tubulin modifications in singlet microtubules of the Drosophila sperm tail
Authors: Hoyle Henry D. , Turner F. Rudolf , Raff Elizabeth C. 
Published: January 2008

AbstractDrosophila melanogaster sperm tubulins are posttranslationally glutamylated and glycylated. We show here that axonemes are the substrate for these tubulin C‐terminal modifications. Axoneme architecture is required, but full length, motile axonemes are not necessary. Tubulin glutamylation occurs during or shortly after assembly into the axoneme; only glutamylated tubulins are glycylated. Tubulins in other testis microtubules are not modified. Only a small subset of total Drosophila sperm axoneme tubulins have these modifications. Biochemical fractionation of Drosophila sperm showed that central pair and accessory microtubules have the majority of poly‐modified tubulins, whereas doublet microtubules have only small amounts of mono‐ and oligo‐modified tubulins. Glutamylation patterns for different β‐tubulins experimentally assembled into axonemes were consistent with utilization of modification sites corresponding to those identified in other organisms, but surrounding sequence context was also important. We compared tubulin modifications in the 9 + 9 + 2 insect sperm tail axonemes of Drosophila with the canonical 9 + 2 axonemes of sperm of the sea urchin Lytichinus pictus and the 9 + 0 motile sperm axonemes of the eel Anguilla japonica. In contrast to Drosophila sperm, L. pictus sperm have equivalent levels of modified tubulins in both doublet and central pair microtubule fractions, whereas the doublets of A. japonica sperm exhibit little glutamylation but extensive glycylation. Tubulin C‐terminal modifications are a prevalent feature of motile axonemes, but there is no conserved pattern for placement or amount of these modifications. We conclude their functions are likely species‐specific. Cell Motil. Cytoskeleton 2008. © 2008 Wiley‐Liss, Inc.
Changes in the magnitude and distribution of forces at different dictyostelium developmental stages
Authors: Delanoë‐Ayari H. , Iwaya S. , Maeda Y. T. , Inose J. , Rivière C. , Sano M. , Rieu J.‐P. 
Published: January 2008

AbstractThe distribution of forces exerted by migrating Dictyostelium amebae at different developmental stages was measured using traction force microscopy. By using very soft polyacrylamide substrates with a high fluorescent bead density, we could measure stresses as small as 30 Pa. Remarkable differences exist both in term of the magnitude and distribution of forces in the course of development. In the vegetative state, cells present cyclic changes in term of speed and shape between an elongated form and a more rounded one. The forces are larger in this first state, especially when they are symmetrically distributed at the front and rear edge of the cell. Elongated vegetative cells can also present a front‐rear asymmetric force distribution with the largest forces in the crescent‐shaped rear of the cell (uropod). Pre‐aggregating cells, once polarized, only present this last kind of asymmetric distribution with the largest forces in the uropod. Except for speed, no cycle is observed. Neither the force distribution of pre‐aggregating cells nor their overall magnitude are modified during chemotaxis, the later being similar to the one of vegetative cells (F0 ∼ 6 nN). On the contrary, both the force distribution and overall magnitude is modified for the fast moving aggregating cells. In particular, these highly elongated cells exert lower forces (F0 ∼ 3 nN). The location of the largest forces in the various stages of the development is consistent with the myosin II localization described in the literature for Dictyostelium (Yumura et al.,1984. J Cell Biol 99:894–899) and is confirmed by preliminary experiments using a GFP‐myosin Dictyostelium strain. Cell Motil. Cytoskeleton, 2008. © 2008 Wiley‐Liss, Inc.
Inhibition of HIV‐1 by a Peptide Ligand of the Genomic RNA Packaging Signal Ψ
Authors: Dietz Julia , Koch Joachim , Kaur Ajit , Raja Chinnappan , Stein Stefan , Grez Manuel , Pustowka Anette , Mensch Sarah , Ferner Jan , Möller Lars , Bannert Norbert , Tampé Robert , Divita Gilles , Mély Yves , Schwalbe Harald , Dietrich Ursula 
Published: January 2008

AbstractThe interaction of the nucleocapsid NCp7 of the human immunodeficiency virus type 1 (HIV‐1) Gag polyprotein with the RNA packaging signal Ψ ensures specific encapsidation of the dimeric full length viral genome into nascent virus particles. Being an essential step in the HIV‐1 replication cycle, specific genome encapsidation represents a promising target for therapeutic intervention. We previously selected peptides binding to HIV‐1 Ψ‐RNA or stem loops (SL) thereof by phage display. Herein, we describe synthesis of peptide variants of the consensus HWWPWW motif on membrane supports to optimize Ψ‐RNA binding. The optimized peptide, psi‐pepB, was characterized in detail with respect to its conformation and binding properties for the SL3 of the Ψ packaging signal by NMR and tryptophan fluorescence quenching. Functional analysis revealed that psi‐pepB caused a strong reduction of virus release by infected cells as monitored by reduced transduction efficiencies, capsid p24 antigen levels, and electron microscopy. Thus, this peptide shows antiviral activity and could serve as a lead compound to develop new drugs targeting HIV‐1.
High‐precision measurement of internuclear distances using solid‐state NMR
Authors: Lee Jae‐Seung , Khitrin Anatoly K. 
Published: January 2008

AbstractToday, nuclear magnetic resonance (NMR) is among the most efficient tools in structural studies. Measurement of interatomic distances is the most common way of determining high‐resolution structures of molecules using NMR techniques. In this article, we describe NMR techniques for static powder samples, based on a two‐dimensional single‐echo scheme, enhanced with adiabatic cross‐polarization. They can significantly increase the accuracy of measuring internuclear distances and turn NMR into a high‐precision crystallographic technique, complementing the X‐ray, and neutron‐scattering methods. Experimental examples are presented for intramolecular CN and CC distances in α‐crystalline form of glycine. © 2008 Wiley Periodicals, Inc. Concepts Magn Reson Part A 32A: 56–67, 2008.
NMR and the uncertainty principle: How to and how not to interpret homogeneous line broadening and pulse nonselectivity. II. The Fourier connection
Authors: Szántay Csaba 
Published: January 2008

AbstractBy building on the nomenclature introduced and the fundamental ideas discussed in Part I, I now continue my preliminary review of the basic concepts we need for exploring the issues surrounding the uncertainty principles in the context of our “Two NMR Problems” (namely: both the essense of homogeneous NMR line broadening, as well as the fact that a short monochromatic RF pulse exhibits a polychromatic spectral bandwidth, and consequently gives a broad off‐resonance NMR excitation band, are often rationalized in terms of a superficial and/or misguided use of the “uncertainty principle”). To that end, in Part II, I discuss Fourier theory in a way that is hoped to offer a number of delicate, important, and interesting insights that are usually not readily available from more conventional texts. © 2008 Wiley Periodicals, Inc. Concepts Magn Reson Part A 32A: 1–33, 2008.
Natural killer cells infiltrating human nonsmall‐cell lung cancer are enriched in CD56brightCD16− cells and display an impaired capability to kill tumor cells
Authors: Carrega Paolo , Morandi Barbara , Costa Roberta , Frumento Guido , Forte Giuseppe , Altavilla Giuseppe , Ratto Giovanni Battista , Mingari Maria Cristina , Moretta Lorenzo , Ferlazzo Guido 
Published: January 2008

AbstractBACKGROUND.Despite natural killer (NK) cells being originally identified and named because of their ability to kill tumor cells in vitro, only limited information is available on NK cells infiltrating malignant tumors, especially in humans.METHODS.NK cells infiltrating human nonsmall cell lung cancers (NSCLC) were analyzed with the aim of identifying their potential protective role in an antitumor immune response. Both relevant molecule expression and functions of NK cells infiltrating NSCLC were analyzed in comparison with autologous NK cells isolated from either peritumoral normal lung tissues or peripheral blood.RESULTS.The CD56brightCD16− NK cell subset was consistently observed as being highly enriched in tumor infiltrate and displayed activation markers, including NKp44, CD69, and HLA‐DR. Remarkably, the cytolytic potential of NK cells isolated from cancer tissues was lower than that of NK cells from peripheral blood or normal lung tissue, whereas no difference was observed regarding their capability of producing cytokines. With regard to their localization within tumor, NK cells were found in tumor stroma, whereas they were not in direct contact with cancer cells.CONCLUSIONS.For the first time NK cells infiltrating NSCLC have been characterized and it is shown that they are mainly capable of producing relevant cytokines rather than exerting direct cancer cell killing. Cancer 2008. © 2008 American Cancer Society.
Lymphovascular invasion as a tool to further subclassify T1b esophageal adenocarcinoma
Authors: Cen Putao , Hofstetter Wayne L. , Correa Arlene M. , Wu Tsung‐Teh , Lee Jeffery H. , Ross William A. , Davilla Marta , Swisher Stephen G. , Fukami Norio , Rashid Asif , Maru Dipen , Ajani Jaffer A. 
Published: January 2008

AbstractBACKGROUND.Lymphovascular invasion (LVI) and/or lymph node metastases (LNM) adversely influence the overall survival (OS) of patients with T1 esophageal adenocarcinoma. Although endoscopic therapy may be adequate for patients with T1a cancer, patients with T1b cancer require esophagectomy/lymphadenectomy. The authors hypothesized that LVI status would subclassify T1b cancers and facilitate new therapeutic strategies.METHODS.Ninety‐nine consecutive patients with T1 adenocarcinoma were analyzed after they underwent esophagectomy/lymphadenectomy. LNM was assessed in all patients, and LVI was assessed in 89 patients. OS was correlated with pathologic cancer stage in association with LVI and LNM.RESULTS.The 5‐year OS rate for patients with T1a tumors (88%) was superior to that for patients with T1b tumors (62%; P = .001). The 5‐year OS rate for patients who had cancers without LVI (85%) was superior to the rate for patients who had cancers with LVI (36%; P = .0001). It is noteworthy that, for cancers without LVI, the 5‐year OS rate for patients with T1b tumors (77%) was similar to the rate for patients with T1a tumors (90%; P = .08), but it was superior to the rate for patients with T1b tumors that had LVI (27%; P = .006). The presence of LVI and/or LNM resulted in worse 5‐year OS (≤37%) compared with the lack of LVI and/or LNM (88%; P < .001). The rate of LNM for patients who had T1b tumors without LVI still was 19%, and the relapse rate was 16%.CONCLUSIONS.The current results demonstrated that LVI distinguishes the biologic behavior of early esophageal cancer, and patients who have T1b cancer without LVI have a clinical biology similar to that of patients with T1a cancer. If LNM before surgery can be diagnosed with high sensitivity by better endoscopic techniques and/or molecular biomarkers, then a new therapeutic paradigm for T1b cancers could emerge. Further research is needed on patients with T1b esophageal adenocarcinoma. Cancer 2008. © 2008 American Cancer Society.
JC virus T‐antigen expression in sporadic adenomatous polyps of the colon
Authors: Jung Woon‐Tae , Li Mei‐Shu , Goel Ajay , Boland C. Richard 
Published: January 2008

AbstractBACKGROUND.JC virus (JCV) has been implicated in the pathogenesis of colorectal cancer; however, its role in premalignant lesions is unknown. The hypothesis that JCV DNA sequences and T‐antigen (T‐Ag) expression may be present in adenomatous polyps of the colon was tested. Furthermore, an association between JCV and microsatellite instability (MSI) was also sought in these lesions.METHODS.DNA was extracted from 74 paraffin‐embedded adenomatous polyps. JCV gene sequences were amplified by polymerase chain reaction (PCR), and the specificity confirmed by DNA sequencing. Immunohistochemical staining was performed to localize T‐Ag expression in the adenomas using a monoclonal antibody. For microsatellite instability analysis, 5 mononucleotide repeat markers (BAT‐25, BAT‐26, NR‐21, NR‐24, and NR‐27) were coamplified in a pentaplex PCR and analyzed for deletion mutations.RESULTS.JCV T‐Ag sequences were found in 82% (61 of 74) of adenomas, and T‐Ag protein was expressed in 16% (12 of 74) of these polyps. The T‐Ag staining was localized exclusively in the nuclei of adenoma cells, but never in the cytoplasm or the adjacent nonneoplastic cells. The prevalence of MSI‐H and non‐MSI‐H (MSI‐L/MSS) in adenomatous polyps was 9.5% (7 of 74) and 90.5% (67 of 74), respectively. Among the 61 adenomas that harbored JCV sequences, 8% (5 of 61) were MSI‐H, and similarly among 12 adenomatous polyps expressing T‐Ag protein 8% (1 of 12) of the adenomatous polyps were MSI‐H.CONCLUSIONS.JCV T‐Ag DNA sequences are frequently present in adenomatous polyps of the colon, and T‐Ag is expressed specifically in the nuclei of these premalignant lesions. This study indicates that JCV T‐Ag is present in the early stage of colonic carcinogenesis. Future studies will be required to determine the molecular mechanism of carcinogenesis in these JCV‐infected lesions. Cancer 2008. © 2008 American Cancer Society.
Fixation of CO2 by Electrocatalytic Reduction and Electropolymerization in Ionic Liquid–H2O Solution
Authors: Chu Daobao , Qin Guoxu , Yuan Ximei , Xu Mai , Zheng Peng , Lu Jia 
Published: January 2008

AbstractThe electrocatalytic synthesis of low‐density polyethylene (LDPE) from carbon dioxide on a nanostructured (ns)TiO2 film electrode was investigated by controlled potential electrolysis in a solvent mixture of water and the ionic liquid 1‐ethyl‐3‐methylimidazolium tetrafluoroborate ([EMI]BF4) at room temperature under ambient pressure. Under these conditions, the nsTiO2 film is remarkably efficient and selective for the electroreduction of CO2. The current efficiency for the formation of the electrolytic product is about 8–14 % at −1.50 V (vs SCE). The electrocatalytic activity of the electrode in the electrochemical reduction of CO2 was investigated by cyclic voltammetry (CV), and the probable electrode reaction mechanism is discussed.