bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cationic nitrile‐functionalized Ag(I)‐ and Hg(II)‐N‐heterocyclic carbene complexes of CCC, CNC, and NCN pincer‐type carbene ligands: Synthesis, crystal structures, and characterization
Authors: Haque Rosenani A. , Zulikha H. Zetty , Ghdhayeb Mohammed Z. , Budagumpi Srinivasa , Salman Abbas Washeel 
Published: August 2012

AbstractThree nitrile‐functionalized (benz)imid‐ zaolium derivatives with CCC, CNC, and NCN coordination pockets have been synthesized and isolated as the bromide salts and are converted into their hexafluorophosphate counterparts (5–7) by ligand metathesis. N‐heterocyclic carbene Ag(I)‐ and Hg(II)‐complexes (8–10 and 11–13) are readily formed in good to excellent yields from ligand precursors 5–7 and Ag2O and Hg(OAc)2, respectively. All reported compounds have been characterized by various spectral and analytical techniques, such as FTIR, 1H, and 13C NMR spectroscopy and X‐ray diffraction studies. Solid‐state structures of carbene precursors 5, 7, and an Ag(I)–carbene complex 10 have been determined crystallographically. Single crystal X‐ray crystallography of complex 10 reveals the chelation of carbene carbons to metal center in almost a linear manner. © 2012 Wiley Periodicals, Inc. Heteroatom Chem 23:486–497, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/hc.21041
Receptor for activated C kinase 1 promotes hepatocellular carcinoma growth by enhancing mitogen-activated protein kinase kinase 7 activity
Authors: Guo Yuanyuan , Wang Wendie , Wang Jing , Feng Jiannan , Wang Qingyang , Jin Jianfeng , Lv Ming , Li Xinying , Li Yan , Ma Yuanfang , Shen Beifen , Zhang Jiyan 
Published: August 2012

Abstract
c-Jun N-terminal protein kinase (JNK) is a member of the mitogen-activated protein kinase (MAPK) superfamily. The activation of JNK is mediated by sequential protein phosphorylation through a MAPK module, namely, MAPK kinase kinase (MAP3K or MEKK) → MAPK kinase (MAP2K or MKK) → MAPK. Elevated levels of JNK activity have been frequently observed in hepatocellular carcinoma (HCC) and have been demonstrated to contribute to HCC growth by promoting HCC cell proliferation and resistance to tumor necrosis factor–related apoptosis-inducing ligand (TRAIL)- or Fas-mediated apoptosis. Chronic inflammation contributes to the up-regulation of JNK activity in HCC. However, it remains unknown whether aberrant JNK activity also results from some cell intrinsic defect(s). Here, we show that receptor for activated C kinase 1 (RACK1), an adaptor protein implicated in the regulation of multiple signaling pathways, could engage in a direct interaction with MKK7, the JNK-specific MAP2K, in human HCC cells. Levels of RACK1 protein show correlation with the activity of the JNK pathway in human HCC tissues and cell lines. RACK1 loss-of-function or gain-of-function analyses indicate that RACK1 enhances MKK7/JNK activity in human HCC cells. Further exploration reveals that the interaction of RACK1 with MKK7 is required for the enhancement of MKK7/JNK activity by RACK1. RACK1/MKK7 interaction facilitates the association of MKK7 with MAP3Ks, thereby enhancing MKK7 activity and promoting in vitro HCC cell proliferation and resistance to TRAIL- or Fas-mediated apoptosis as well as in vivo tumor growth. Conclusion: Overexpressed RACK1 augments JNK activity and thereby promotes HCC growth through directly binding to MKK7 and enhancing MKK7 activity. (Hepatology 2013)
Differentiated umbilical cord matrix stem cells as a new in vitro model to study early events during hepatitis B virus infection
Authors: Paganelli Massimiliano , Dallmeier Kai , Nyabi Omar , Scheers Isabelle , Kabamba Benoît , Neyts Johan , Goubau Patrick , Najimi Mustapha , Sokal Etienne M. 
Published: August 2012

Abstract
The role of cell differentiation state on hepatitis B virus (HBV) replication has been well demonstrated, whereas how it determines cell susceptibility to HBV entry is far less understood. We previously showed that umbilical cord matrix stem cells (UCMSC) can be differentiated towards hepatocyte-like cells in vitro. In this study we infected undifferentiated (UD-) and differentiated (D-) UCMSCs with HBV and studied the infection kinetics, comparing them to primary human hepatocytes (PHHs). UD-UCMSCs, although permissive to viral binding, had a very limited uptake capacity, whereas D-UCMSCs showed binding and uptake capabilities similar to PHHs. Likewise, asialoglycoprotein receptor (ASGPR) was up-regulated in UCMSCs upon differentiation. In D-UCMSCs, a dose-dependent inhibition of HBV binding and uptake was observed when ASGPR was saturated with known specific ligands. Subsequent viral replication was shown in D-UCMSCs but not in UD-UCMSCs. Susceptibility of UCMSCs to viral replication correlated with the degree of differentiation. Replication efficiency was low compared to PHHs, but was confirmed by (1) a dose-dependent inhibition by specific antiviral treatment using tenofovir; (2) the increase of viral RNAs along time; (3) de novo synthesis of viral proteins; and (4) secretion of infectious viral progeny. Conclusion: UCMSCs become supportive of the entire HBV life cycle upon in vitro hepatic differentiation. Despite low replication efficiency, D-UCMSCs proved to be fully capable of HBV uptake. Overall, UCMSCs are a unique human, easily available, nontransformed, in vitro model of HBV infection that could prove useful to study early infection events and the role of the cell differentiation state on such events. (Hepatology 2013)
MicroRNA-140 acts as a liver tumor suppressor by controlling NF-κB activity by directly targeting DNA methyltransferase 1 (Dnmt1) expression
Authors: Takata Akemi , Otsuka Motoyuki , Yoshikawa Takeshi , Kishikawa Takahiro , Hikiba Yohko , Obi Shuntaro , Goto Tadashi , Kang Young Jun , Maeda Shin , Yoshida Haruhiko , Omata Masao , Asahara Hiroshi , Koike Kazuhiko 
Published: August 2012

Abstract
MicroRNAs (miRNAs) are small RNAs that regulate the expression of specific target genes. While deregulated miRNA expression levels have been detected in many tumors, whether miRNA functional impairment is also involved in carcinogenesis remains unknown. We investigated whether deregulation of miRNA machinery components and subsequent functional impairment of miRNAs are involved in hepatocarcinogenesis. Among miRNA-containing ribonucleoprotein complex components, reduced expression of DDX20 was frequently observed in human hepatocellular carcinomas, in which enhanced nuclear factor-κB (NF-κB) activity is believed to be closely linked to carcinogenesis. Because DDX20 normally suppresses NF-κB activity by preferentially regulating the function of the NF-κB-suppressing miRNA-140, we hypothesized that impairment of miRNA-140 function may be involved in hepatocarcinogenesis. DNA methyltransferase 1 (Dnmt1) was identified as a direct target of miRNA-140, and increased Dnmt1 expression in DDX20-deficient cells hypermethylated the promoters of metallothionein genes, resulting in decreased metallothionein expression leading to enhanced NF-κB activity. MiRNA-140-knockout mice were prone to hepatocarcinogenesis and had a phenotype similar to that of DDX20 deficiency, suggesting that miRNA-140 plays a central role in DDX20 deficiency-related pathogenesis. Conclusion: These results indicate that miRNA-140 acts as a liver tumor suppressor, and that impairment of miRNA-140 function due to a deficiency of DDX20, a miRNA machinery component, could lead to hepatocarcinogenesis. (Hepatology 2013)
Further Withaphysalin Derivatives from Acnistus arborescens
Authors: Maia Ana Isabel V. , Braz‐Filho Raimundo , Silveira Edilberto R. , de Simone Carlos Alberto , Pessoa Otília Deusdênia L. 
Published: August 2012

AbstractTwo new epimeric chlorinated withaphysalins, rel‐(4β,5β,6α,18S,22R)‐ and rel‐(4β,5β,6α,18R,22R)‐6‐chloro‐18,20‐epoxy‐18‐ethoxy‐4,5‐dihydroxy‐1‐oxowitha‐2,24‐diene‐26,22‐lactone (1 and 2 resp.), together with the new rel‐(4β,5β,6α,18R,22R)‐6‐chloro‐18,20‐epoxy‐4,5‐dihydroxy‐18‐methoxy‐1‐oxowitha‐2,24‐diene‐26,22‐lactone (3) and rel‐(3β,4β,5β,6β,18R,22R)‐5,6:18,20‐diepoxy‐3,18‐diethoxy‐4‐hydroxy‐1‐oxowith‐24‐ene‐26,22‐lactone (4) were isolated from the leaves of Acnistus arborescens and named withaphysalins T–W, respectively. The final structures and the complete 1H‐ and 13C‐NMR assignments of the three chlorowithaphysalins 1–3 were performed by means of HR‐ESI‐MS and 1D‐ and 2D‐NMR experiments, including COSY, HSQC, and HMBC, beside comparison with spectral data of analogous compounds from the literature. The structure of 4 was also confirmed by means of a single‐crystal X‐ray diffraction analysis.
Diketopiperazine Alkaloids Produced by the Endophytic Fungus Aspergillus fumigatus from the Stem of Erythrophloeum fordiiOliv.
Authors: Liu Yu‐Xi , Ma Shuang‐Gang , Wang Xiao‐Jing , Zhao Nan , Qu Jing , Yu Shi‐Shan , Dai Jun‐Gui , Wang Ying‐Hong , Si Yi‐Kang 
Published: August 2012

AbstractFour new diketopiperazine alkaloids, rel‐(8R)‐9‐hydroxy‐8‐methoxy‐18‐epi‐fumitremorgin C (1), rel‐(8S)‐19,20‐dihydro‐9,20‐dihydroxy‐8‐methoxy‐9,18‐di‐epi‐fumitremorgin C (2), rel‐(8S,19S)‐19,20‐dihydro‐9,19,20‐trihydroxy‐8‐methoxy‐9‐epi‐fumitremorgin C (3), and (3S,8S,9S,18S)‐8,9‐dihydroxyspirotryprostatin A (4), together with the eight known compounds 5–12, were isolated from the endophytic fungus Aspergillus fumigatus. The structures of the new compounds were determined by extensive spectroscopic methods including HR‐ESI‐MS, NMR, and CD experiments. Compound 12 showed weak inhibitory activity in vitro against the release of β‐glucuronidase in rat polymorphonuclear leukocytes induced by the platelet‐activating factor. None of the twelve compounds exhibited detectable cytotoxic activities toward five human tumor cell lines (HCT‐8, Bel‐7402, BGC‐823, A549, and A2780) in the MTT assay.
The Reactions of α‐Ylidene (Vinylidene, Benzylidene, Styrylmethylidene) Bis[carbonyls] with Copper Mono/Bis[carbonylcarbenoids]
Authors: Merey Gökçe , Kaya Mustafa , Anaç Olcay 
Published: August 2012

AbstractThe [Cu(acac)2]‐catalyzed reactions of various α,β,γ,δ‐unsaturated bis‐ketones/bis‐esters/bis‐keto esters with dimethyl diazomalonate and ethyl diazoacetate were studied. Total steric/electronic convenience of the present reaction paths was investigated. Methoxy/nitro substituents in m‐/p‐positions on benzylidene biscarbonyls did not alter the general routes of the reactions, supporting concerted mechanism. Dihydrobenzoxepine/oxepine formation was sterically sensitive to the related pre‐ring conformation, and dihydrofurans were effected by both charge control and steric factors.
Alkaloids from the Stems of Glycosmis pentaphylla
Authors: Yang Guang‐Zhong , Wu Yi , Chen Yu 
Published: August 2012

AbstractA new simple carbazole alkaloid, 4‐(7‐hydroxy‐3‐methoxy‐6‐methyl‐9H‐carbazol‐4‐yl)but‐3‐en‐2‐one (1), and two new dimeric carbazole alkaloids, bisglybomine B (2) and biscarbalexine A (3), together with seven known alkaloids, were isolated from the stems of Glycosmis pentaphylla. Their structures were elucidated by spectroscopic methods, especially 2D‐NMR techniques.
A New Megastigmane Palmitate and a New Oleanane Triterpenoid from Aster yomenaMakino
Authors: Jin Qinglong , Jin Hong‐Guang , Kim A Ryun , Woo Eun‐Rhan 
Published: August 2012

AbstractA new megastigmane palmitate, 9‐oxomegastigm‐5(13)‐ene‐2β‐palmitate (1), and a new oleanane triterpenoid, (3β)‐3,23,28‐trihydroxyolean‐12‐en‐11‐one (2), together with three known oleanane‐type triterpenoids, β‐amyrin (3), erythrodiol (4), and (3β)‐olean‐12‐ene‐3,23,28‐triol (5), were isolated from the aerial parts of Aster yomena (Asteraceae). Their structures were identified based on 1D‐ and 2D‐NMR analysis, including 1H,1H‐COSY, HSQC, HMBC, and NOESY techniques.
Improved Synthesis of Indirubin Derivatives by Sequential Build‐Up of the Indoxyl Unit: First Preparation of Fluorescent Indirubins
Authors: Riepl Herbert M. , Urmann Corinna 
Published: August 2012

AbstractIndirubin, present in extracts of Isatis tinctoria and some other plant species, has promising cytotoxicity against a variety of cell lines by inhibition of cyclin‐dependent kinases. Chemical synthesis of its derivatives relies on the combination of isatins and 2,3‐dihydro‐1H‐indol‐3‐one (‘indoxyl’) derivatives and usually yields indigo as well as other by‐products. Inspection of the hydrolysis of the long‐known condensation products of 2‐thioxothiazolidin‐4‐one with isatins gave useful hints for an improved synthesis of indirubins: this reaction does not yield quinoline derivatives but 2‐(2,3‐dihydro‐2‐oxo‐1H‐indol‐3‐ylidene)‐2‐sulfanyl acetic acids. By substitution of the sulfanyl group in this oxindoles with anilines and straightforward cyclization under Nazarov conditions, a broad variety of indirubins substituted in the indoxyl ring system are thus available, usually in very good purity and yield. Use of naphthylamines in this reaction sequence yields various fluorescent substances with λfl at ca. 630 nm.
Modified Riemschneider Reaction of 3‐Thiocyanatoquinolinediones
Authors: Rudolf Ondřej , Mrkvička Vladimír , Lyčka Antonín , Rouchal Michal , Klásek Antonín 
Published: August 2012

AbstractThe Riemschneider reaction of 3‐thiocyanatoquinoline‐2,4(1H,3H)‐diones with conc. H2SO4 was investigated. Using different reaction conditions, 13 types of reaction products were isolated. Compounds bearing a Me, Et, or Bu group at C(3) afforded mainly [1,3]thiazolo[5,4‐c]quinoline‐2,4‐diones and 1,9b‐dihydro‐9b‐hydroxythiazolo[5,4‐c]quinoline‐2,4‐diones. In the case of the 3‐Bu derivatives of the starting compounds, C‐debutylation was also observed. If a Bn group is present at C(3), rapid C‐debenzylation of the starting thiocyanates occurred, yielding [1,3]oxathiolo[4,5‐c]quinoline‐2,4‐diones, and mixtures of mono‐, di‐, and trisulfides derived from 4‐hydroxy‐3‐sulfanylquinoline‐2‐ones. The reaction mechanism of all of the transformations is discussed. All new compounds were characterized by IR, 1H‐ and 13C‐NMR, and EI and ESI mass spectra, and in some cases, 15N‐NMR spectra were also used to characterize new compounds.
Synthesis of Aib‐Pro Oligopeptides by Repeated Azirine Coupling with the Aib‐Pro Synthon
Authors: Stoykova Svetlana A. , Linden Anthony , Heimgartner Heinz 
Published: August 2012

AbstractA new synthesis of (Aib‐Pro)n oligopeptides (n=2, 3, and 4) via azirine coupling by using the dipeptide synthon methyl N‐(2,2‐dimethyl‐2H‐azirin‐3‐yl)‐L‐prolinate (1b; Fig. 1) is presented. The most important feature of the employed protocol is that no activation of the acid component is necessary, i.e., no additional reagents are required, and the coupling reaction is performed under mild conditions at room temperature. As an attempt to provide an answer to the question of the preferred conformation of the prepared molecules, we carried out experiments by using NMR techniques and X‐ray crystallography. For example, in the case of the hexapeptide 11, it was possible to compare the conformations in the crystalline state and in solution. After the selective hydrolysis of the methyl ester p‐BrBz‐(Aib‐Pro)4‐OMe (13) under basic conditions, the corresponding octapeptide acid was obtained, which was then converted into the octapeptide amide p‐BrBz‐(Aib‐Pro)4‐NHC6H13 (15) by using standard coupling conditions and activating reagents (HOBt/TBTU/DIEA) of the peptide synthesis. The conformation of this compound, as well as those of the tetrapeptides 14 and 18, was also established by X‐ray crystallography and in solution by NMR techniques. In the crystalline state, a β‐bend ribbon structure is the preferred conformation, and similar conformations are formed in solution.
Preparation and Characterization of NewC2‐ andC1‐Symmetric Nitrogen, Oxygen, Phosphorous, and Sulfur Derivatives and Analogs of TADDOL. Part III
Authors: Seebach Dieter , Beck Albert K. , Bichsel Hans‐Ulrich , Pichota Arkadius , Sparr Christof , Wünsch Ralf , Schweizer W. Bernd 
Published: August 2012

AbstractA brief overview is presented of the field of organocatalysis using chiral H‐bond donors, chiralBrønstedacids, and chiral counter‐anions (Fig. 1). The role of TADDOLs (=α,α,α′,α′‐tetraaryl‐1,3‐dioxolane‐4,5‐dimethanols) as H‐bond donors and the importance of an intramolecular H‐bond for acidity enhancement are discussed. Crystal structures of TADDOLs and of their N‐, S‐, and P‐analogs (Figs. 2and3) point the way to proposals of mechanistic models for the action of TADDOLs as organocatalysts (Scheme 1). Simple experimental two‐step procedures for the preparation of the hitherto strongest known TADDOL‐derived acids, the bicyclic phosphoric acids (2inScheme 2) and of a phosphoric‐trifluorosulfonic imide (9inScheme 4), are disclosed. The mechanism of sulfinamide formation in reactions of TADDAMIN with trifluoro‐sulfonylating reagents is discussed (Scheme 3). pKaMeasurements of TADDOLs and analogs in DMSO (reported in the literature;Fig. 5) and in MeO(CH2)2OH/H2O (described herein;Fig. 6) provide information about further possible applications of this type of compounds as strong chiralBrønstedacids in organocatalysis.
Experimental study of free convection heat transfer and condensation of vapor of humid air over an inclined cold tube
Authors: Nabovati Behnam , Yaghoubi Mahmood , Avara Abdollah 
Published: August 2012

AbstractIn this study condensation heat transfer on a cold inclined circular cylinder due to natural convection for various conditions is investigated experimentally. The cylinder is placed in an isolated test room to permit pure natural circulation of ambient air. Ambient temperature and humidity of the test room are controlled by a refrigeration cycle and humidifying. The ambient relative air humidity changed in the range of 30 to 50% and temperature from 25 to 35 °C. The ethylene‐glycol/water solution is used as a refrigerant to control and keep the temperature of the test section at a constant value. The cold surface temperature is varied from 2 to 6 °C. The condensation rate and heat flux are found to depend mainly on time, temperature difference between ambient air and cold surface, ambient relative humidity, and tube inclination. Results are plotted for various conditions with respect to time. The experimental results are used to propose a correlation to predict the condensate mass flow rate for free convection heat transfer. © 2012 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley Online Library (wileyonlinelibrary.com/journal/htj). DOI 10.1002/htj.21015
Endogenous inhibitor proteins that connect Ser/Thr kinases and phosphatases in cell signaling
Authors: Eto Masumi , Brautigan David L. 
Published: August 2012

AbstractProtein phosphatase activity acts as a primary determinant of the extent and duration of phosphorylation of cellular proteins in response to physiological stimuli. Ser/Thr protein phosphatase‐1 (PP1) belongs to the PPP superfamily, and is associated with regulatory subunits that confer substrate specificity, allosteric regulation, and subcellular compartmentalization. In addition, all eukaryotic cells contain multiple heat‐stable proteins that originally were thought to inhibit phosphatase catalytic subunits released from the regulatory subunits, as a fail‐safe mechanism. However, discovery of C‐kinase‐activated PP1 inhibitor, Mr of 17 kDa (CPI‐17) required fresh thinking about the endogenous inhibitors as specific regulators of particular phosphatase complexes, acting in addition to, not instead of, regulatory subunits. The cellular actions of the endogenous inhibitors are controlled by phosphorylation, connecting them to kinase pathways. More recent progress has unveiled additional functions of PP1 inhibitor‐2 (I‐2), including regulation of protein kinases. Transcriptional mechanisms govern the expression levels of CPI‐17 in response to stimuli. If true for other inhibitor proteins, they have the potential of being diagnostic markers for pathological conditions. We discuss specific examples of PP1 inhibitor proteins regulating particular cellular functions and the rationale for incorporating phosphatase inhibitor proteins in development of new therapeutic strategies. © 2012 IUBMB IUBMB Life, 2012
Temporal summation of second pain: Variability in responses to a fixed protocol
Authors: Anderson R.J. , Craggs J.G. , Bialosky J.E. , Bishop M.D. , George S.Z. , Staud R. , Robinson M.E. 
Published: August 2012

AbstractBackgroundTemporal summation of second pain (TSSP) is relevant for the study of central sensitization, and refers to increased pain evoked by repetitive stimuli at a constant intensity. While the literature reports on participants whose pain ratings increase with successive stimuli, response to a TSSP protocol can be variable. The aim of this study was to characterize the full range of responses to a TSSP protocol in pain‐free adults.MethodThree hundred twelve adults received a train of brief, repetitive heat stimuli at a fixed temperature and rated the intensity of second pain after each pulse. TSSP response (Δ in pain ratings) was quantified using the most common methods in the literature, and response groups were formed: TSSP (Δ > 0), no change (Δ = 0), and temporal decrease in second pain (TDSP) (Δ < 0). A cluster analysis was performed on the Δ values to empirically derive response groups.ResultsDepending on how TSSP response was quantified, 61–72% of the sample demonstrated TSSP, 11–28% had no change in pain ratings and 0–20% demonstrated TDSP. The cluster analysis found that the majority (59%) of participants fell in the no change cluster, 29% clustered into the TSSP group and 12% in the TDSP cluster.ConclusionsUsing a fixed thermal paradigm, pain‐free adults exhibit substantial variability in response to a TSSP protocol not well characterized by group‐mean slopes. Studies are needed to determine TSSP response patterns in clinical samples, identify predictors of response and determine the clinical implications of response variability.
Coffee attenuates fibrosis by decreasing the expression of TGF‐β and CTGF in a murine model of liver damage
Authors: Arauz Jonathan , Moreno Marina Galicia‐ , Cortés‐Reynosa Pedro , Salazar Eduardo Pérez , Muriel Pablo 
Published: August 2012

ABSTRACTThis study was performed to evaluate the antifibrotic properties of coffee in a model of liver damage induced by repeated administration of thioacetamide (TAA) in male Wistar rats. In this study, cirrhosis was induced by chronic TAA administration and the effects of co‐administration of conventional caffeinated coffee or decaffeinated coffee (CC, DC, respectively) for 8 weeks were evaluated. TAA administration elevated serum alkaline phosphatase (AP), γ‐glutamyl transpeptidase (γ‐GTP) and alanine aminotransferase (ALAT), liver lipid peroxidation, collagen content, depleted liver glycogen and glutathione peroxidase (GPx) activity. Additionally increased levels of a number of proteins were detected including transforming growth factor‐beta (TGF‐β), connective tissue growth factor (CTGF) and alpha‐smooth muscle actin (α‐SMA), and matrix metalloproteinase (MMP)‐2, 9 and 13. Coffee suppressed most of the changes produced by TAA. Histopathological analysis was in agreement with biochemical and molecular findings. These results indicate that coffee attenuates experimental cirrhosis; the action mechanisms are probably associated with its antioxidant properties and mainly by its ability to block the elevation of the profibrogenic cytokine TGF‐β and its downstream effector CTGF. Various components of coffee that have been related to such a favorable effect include caffeine, coffee oils kahweol, cafestol and antioxidant substances; however, no definite evidence for the role of these components has been established. These results support earlier findings suggesting a beneficial effect of coffee on the liver. However, more basic clinical studies must be performed to confirm this hypothesis. Copyright © 2012 John Wiley & Sons, Ltd.