bluuebunny/crossref_metadata_2025 huggingface dataset:
Prioritizing new over old: An fMRI study of the preview search task
Authors: Olivers Christian N.L. , Smith Stephen , Matthews Paul , Humphreys Glyn W.
Published: September 2004

In visual search, observers can successfully ignore temporally separated distractors that are presented as a preview before onset of the search display. Previous behavioral studies have demonstrated the involvement of top–down selection mechanisms in preview search, biasing attention against the old set in favor of the more relevant new set. Using functional magnetic resonance imaging, we replicate and extend findings showing the involvement of superior and inferior parietal areas in the preview task when compared to both a relatively easy single‐set search task and a more effortful full‐set search task. In contrast, the effortful full‐set search showed activation in the dorsolateral prefrontal cortex when compared to the single‐set search, suggesting that this area is involved in rejecting additional distractors that could not be separated in time. Hum. Brain Mapp 24:69–78, 2005. © 2004 Wiley‐Liss, Inc.
Antifibrotic effects of a tissue inhibitor of metalloproteinase-1 antibody on established liver fibrosis in rats
Authors: Parsons Christopher J. , Bradford Blair U. , Pan Clark Q. , Cheung Ellen , Schauer Michael , Knorr Andreas , Krebs Barbara , Kraft Sabine , Zahn Stefan , Brocks Bodo , Feirt Nikki , Mei Baisong , Cho Myung-Sam , Ramamoorthi Roopa , Roldan Greg , Ng Paul , Lum Peggy , Hirth-Dietrich Claudia , Tomkinson Adrian , Brenner David A.
Published: September 2004

Liver fibrosis is characterized by increased synthesis, and decreased degradation, of extracellular matrix (ECM) within the injured tissue. Decreased ECM degradation results, in part, from increased expression of tissue inhibitor of metalloproteinase-1 (TIMP-1), which blocks matrix metalloproteinase (MMP) activity. TIMP-1 is also involved in promoting survival of activated hepatic stellate cells (HSCs), a major source of ECM. This study examined the effects of blocking TIMP-1 activity in a clinically relevant model of established liver fibrosis. Rats were treated with carbon tetrachloride (CCl4), or olive oil control, for 6 weeks; 24 days into the treatment, the rats were administered a neutralizing anti-TIMP-1 antibody derived from a fully human combinatorial antibody library (HuCAL), PBS, or an isotype control antibody. Livers from CCl4-treated rats exhibited substantial damage, including bridging fibrosis, inflammation, and extensive expression of smooth muscle α-actin (α-SMA). Compared to controls, rats administered anti-TIMP-1 showed a reduction in collagen accumulation by histological examination and hydroxyproline content. Administration of anti-TIMP-1 resulted in a marked decrease in α-SMA staining. Zymography analysis showed antibody treatment decreased the activity of MMP-2. In conclusion, administration of a TIMP-1 antibody attenuated CCl4-induced liver fibrosis and decreased HSC activation and MMP-2 activity. (Hepatology 2004.)
A dual reporter gene transgenic mouse demonstrates heterogeneity in hepatic fibrogenic cell populations
Authors: Magness Scott T. , Bataller Ramón , Yang Liu , Brenner David A.
Published: September 2004

Activation of hepatic stellate cells (HSCs) and other resident mesenchymal cells into myofibroblasts expressing alpha smooth muscle actin (αSMA) and collagen I is a key event in liver fibrogenesis. However, the temporal expression profiles of αSMA and collagen I genes in these cells is unknown. To address this question, we studied αSMA and collagen α1(I) transcriptional patterns in primary cultures of HSCs, and additionally, in an in vivo model of secondary biliary fibrosis using transgenic mice that express the Discomsoma sp. red fluorescent protein (RFP) and the enhanced green fluorescent protein (EGFP) reporter genes under direction of the mouse αSMA and collagen α1(I) promoter/enhancers, respectively. The αSMA-RFP mice were crossed with collagen-EGFP mice to generate double transgenic mice. Reporter gene expression in cultured HSCs demonstrated that both transgenes were induced at day 3 with continued expression through day 14. Interestingly, αSMA and collagen α1(I) transgenes were not coexpressed in all cells. Flow cytometry analysis showed three different patterns of gene expression: αSMA-RFP positive cells, collagen-EGFP positive cells, and cells expressing both transgenes. αSMA-only and αSMA/collagen expressing cells showed higher expression levels of synaptophysin, reelin, MMP13, TIMP1, and ICAM-1 compared to collagen-only expressing cells, as assessed by real-time PCR. Following bile duct ligation, αSMA and collagen α1(I) transgenes were differentially expressed by peribiliary, parenchymal and vascular fibrogenic cells. Peribiliary cells preferentially expressed collagen α1(I), while parenchymal myofibroblasts expressed both αSMA and collagen α1(I). In conclusion, these data demonstrate heterogeneity of gene expression in myofibroblastic cells during active fibrogenesis. These reporter mice provide a useful tool to further characterize fibrogenic cell types and to evaluate antifibrotic drugs. (Hepatology 2004.)
Opioid receptor blockade reduces Fas-induced hepatitis in mice
Authors: Jaume Martial , Jacquet Sébastien , Cavaillès Pierre , Macé Gaëtane , Stephan Lionel , Blanpied Catherine , Demur Cécile , Brousset Pierre , Dietrich Gilles
Published: September 2004

Fas (CD95)-induced hepatocyte apoptosis and cytotoxic activity of neutrophils infiltrating the injured liver are two major events leading to hepatitis. Because it has been reported that opioids, via a direct interaction, sensitize splenocytes to Fas-mediated apoptosis by upregulating Fas messenger RNA (mRNA) and modulated neutrophil activity, we assumed that opioids may participate in the pathophysiology of hepatitis. Using the hepatitis model induced by agonistic anti-Fas antibody in mice, we showed that opioid receptor blockade reduced liver damage and consequently increased the survival rate of animals when the antagonist naltrexone was injected simultaneously or prior to antibody administration. Treatment of mice with morphine enhanced mortality. Naloxone methiodide—a selective peripheral opioid antagonist—had a protective effect, but the absence of opioid receptors in the liver, together with lack of morphine effect in Fas-induced apoptosis of primary cultured hepatocytes, ruled out a direct effect of opioids on hepatocytes. In addition, the neutralization of opioid activity by naltrexone did not modify Fas mRNA expression in the liver as assessed with real-time quantitative polymerase chain reaction. Injured livers were infiltrated by neutrophils, but granulocyte-depleted mice were not protected against the enhancing apoptotic effect of morphine. In conclusion, opioid receptor blockade improves the resistance of mice to Fas-induced hepatitis via a peripheral mechanism that does not involve a down-modulation of Fas mRNA in hepatocytes nor a decrease in proinflammatory activity of neutrophils. (Hepatology 2004.)
Synthesis of {242}‐ and {323}‐p‐Octiphenyls
Authors: Baudry Yoann , Ronan Dawn , Jeannerat Damien , Matile Stefan
Published: September 2004

The introduction of rigid‐rod molecules as privileged scaffolds has opened routes to otherwise problematic supramolecular architecture like artificial β‐barrels and functional supramolecules covering pores, hosts, sensors, and catalysts. The usefulness of p‐oligophenyls for the construction of functional barrel‐stave architecture has, however, been limited by uniform substitution along the rigid‐rod scaffold. The objective of this report is to overcome this obstacle for the synthesis of p‐octiphenyls with orthogonally protected carboxylic acid groups along the rigid‐rod scaffold. In the reported {242}‐p‐octiphenyl 1, the two peripheral arene moieties carry carboxylic acid groups protected as benzyl esters, whereas the four central carboxylic acid groups are protected orthogonally as tert‐butyl esters (Scheme 2). The complementary orthogonal protection of the three peripheral and the two central arenes is achieved in the {323}‐p‐octiphenyl 2 (Scheme 3). The realized {242}‐ and {323}‐p‐octiphenyls 1 and 2, respectively, provide a complete set for the general access to refined rigid‐rod barrel‐stave architecture with maximized functional plasticity. The need for resolution‐enhanced (aliased) HMBC 2D‐NMR spectroscopy to characterize these refined oligomers is described in the following publication in this issue of Helv. Chim. Acta.
NMR Characterization of Complex p‐Oligophenyl Scaffolds by Means of Aliasing Techniques to Obtain Resolution‐Enhanced Two‐Dimensional Spectra
Authors: Jeannerat Damien , Ronan Dawn , Baudry Yoann , Pinto André , Saulnier Jean‐Paul , Matile Stefan
Published: September 2004

The usefulness of computer‐assisted aliasing to secure maximal resolution of signal clusters in 1H‐ and 13C‐NMR spectra (which is essential for structure determination by HMBC 2D NMR spectroscopy) in minimal acquisition time is exemplified by the complete characterization of the two complementary p‐octiphenyls 1 and 2 with complex substitution patterns. The need for digital resolution near 1 Hz/pt to dissect the extensive signal clusters in the NMR spectra of these refined oligomers excluded structure determination under routine conditions. High resolution was secured by exploiting the low signal density in the 13C dimension of HMBC spectra by using computer‐assisted aliasing to maximize signal density. Based on the observed shifts in DEPT and 1H‐decoupled 13C‐NMR spectra of 1 and 2, computer‐assisted aliasing allowed to reduce the number of required time increments by a factor of 20 to 30 compared to full‐width spectra with identical resolution. Without signal‐to‐noise constraints, this computer‐assisted aliasing reduced the acquisition time for high‐resolution NMR spectra needed for complete characterization of refined oligomers 1 and 2 by the same factor (e.g., from over a day to about an hour). With resolved signal clusters in fully aliased HSQC and HMBC spectra, unproblematic structure determination of 1 and 2 is demonstrated by unambiguous assignment of all C‐ and H‐atoms. These findings demonstrate that computer‐assisted aliasing of the underexploited 13C dimension makes extensive molecular complexity accessible by conventional multidimensional heteronuclear NMR experiments without extraordinary efforts.
Computational Interpretation of Vibrational Optical Activity: The ROA Spectra of (4S)‐4‐Methylisochromane and the (4S)‐Isomers of Galaxolide®
Authors: Zuber Gérard , Hug Werner
Published: September 2004

The reliable computation of Raman‐optical‐activity (ROA) spectra of molecules of the size of the title compounds has, until now, not been possible. We show that our rarefied basis sets yield results in good agreement with the experimental data for (4S)‐4‐methylisochromane (=(4S)‐3,4‐dihydro‐4‐methyl‐1H‐2‐benzopyran; 1), provided the equilibrium between the pseudo‐equatorial and the pseudo‐axial conformers is taken into account. Comparison between the measured and the computed ROA back‐scattering spectra allows the unequivocal assignment of the absolute configuration of the molecule. Comparison with more‐approximate calculations for the larger (4S)‐isomers of Galaxolide® (2), which contain the (4S)‐4‐methylisochromane moiety, shows large‐scale group frequencies on the same chiral fragments of the two molecules. The data confirm that ROA can be generated by interactions extending over several bonds, i.e., over larger distances than can be probed by NMR spectroscopy. Thus, the absolute configuration at C(7) of Galaxolide® is assignable independently of that at C(4). The computation of ROA for forward‐scattering, which will soon be measurable for Galaxolide®, suggests that this scattering geometry provides additional stereochemical information that will be valuable in situations where absolute configurations at several stereogenic centers have to be assigned.
7‐Iodo‐5‐aza‐7‐deazaguanine: Syntheses of Anomeric D‐ and L‐Configured 2‐Deoxyribonucleosides
Authors: Lin Wenqing , Zhang Xiaomei , Seela Frank
Published: September 2004

Iodination of N2‐isobutyryl‐5‐aza‐7‐deazaguanine (7) with N‐iodosuccinimide (NIS) gave 7‐iodo‐N2‐isobutyryl‐5‐aza‐7‐deazaguanine (8) in a regioselective reaction (Scheme 1). Nucleobase‐anion glycosylation of 8 with 2‐deoxy‐3,5‐di‐O‐toluoyl‐α‐D‐ or α‐L‐erythro‐pentofuranosyl chloride furnished anomeric mixtures of D‐ and L‐nucleosides. The anomeric D‐nucleosides were separated by crystallization to give the α‐D‐anomer and β‐D‐anomer with excellent optical purity. Deprotection gave the 7‐iodo‐5‐aza‐7‐deazaguanine 2′‐deoxyribonucleosides 3 (β‐D; ≥99% de) and 4 (α‐D; ≥99% de). The reaction sequence performed with the D‐series was also applied to L‐nucleosides to furnish compounds 5 (β‐L; ≥99% de) and 6 (α‐L; ≥95% de).
Stereospecific Synthesis of Carbanucleotides Designed for Antisense Methodology
Authors: Zhu Xue‐Feng , Nydegger Freddy , Gossauer Albert
Published: September 2004

A short stereospecific synthesis of the carbocyclic 2′‐deoxynucleoside analogues 36 and 37 (Schemes 2 and 5) and 45 and 46 (Schemes 2 and 6) starting from optically active 8,9,10‐trinorborn‐5‐en‐2‐one (1) is described. As two functional groups capable to react with each other are present in the same molecule of the synthetic carbanucleosides, the latter can form polymers similar to oligonucleotides.
New C(4)‐Functionalized Colchicine Derivatives by a Versatile Multicomponent Electrophilic Aromatic Substitution
Authors: Bensel Nicolas , Lagnoux David , Niggli Verena , Wartmann Markus , Reymond Jean‐Louis
Published: September 2004

Electrophilic alkylation of colchicine at C(4) was accomplished by a multicomponent aromatic electrophilic substitution reaction with electrophilic aldehydes and carboxylic acids or amides in H2SO4. A series of new derivatives were obtained and evaluated for their antiproliferative effect towards various tumor cell lines, and their stimulatory effect on the development of polarity in human neutrophils.
Oligonucleotide Analogues with a ‘Nucleobase‐Including Backbone’. Part 10
Authors: Matthews Andrew John , Bhardwaj Punit Kumar , Vasella Andrea
Published: September 2004

The dinucleoside analogues 24, 25, 28–30, and 33 associate in CDCl3 solution. Association constants, as determined from the concentration‐dependent chemical shift for HN(3) of the uridine moiety and from thermodynamic parameters, range from 265 M−1 (33) to 3220 M−1 (30). The association of 31 in CDCl3 is too strong to be determined (concentration independent δ(HN(3)) of ca. 12.8 ppm) and the fully deprotected dimer 32 proved insufficiently soluble in CDCl3. This observation strongly evidences that structural differentiation of oligonucleotides and their analogues into backbone and nucleobases is not required for pairing. The dinucleotide analogues were prepared by O‐alkylation of C(8)‐unsubstituted or of C(8)‐oxymethylated, partially protected adenosines by the C(6)‐mesyloxy‐ or C(6)‐halomethylated uridines 20–22, followed by partial or total deprotection.
Regio‐ and Stereoselective 1,3‐Oxathiolane Formation in the Reaction of Thiolactones with Optically Active Oxiranes
Authors: Fu Changchun , Linden Anthony , Heimgartner Heinz
Published: September 2004

The reactions of 3H‐isobenzofuran‐1‐thione (1) with (S)‐2‐methyloxirane (2) and (R)‐2‐phenyloxirane (6) in the presence of SiO2 in anhydrous CH2Cl2 led to two pairs of diastereoisomeric spirocyclic 1,3‐oxathiolanes, i.e., 3 and 4 with a Me group at C(5′), and 7 and 8 with a Ph group at C(4′), respectively (Schemes 2 and 3). In both cases, 3H‐isobenzofuran‐1‐one (5) was formed as a main product. The analogous reactions of 3,4‐dihydro‐2H‐[1]benzopyran‐2‐thione (9) and 3,4,5,6‐tetrahydro‐2H‐pyran‐2‐thione (14) with 2 and 6 yielded four pairs of the corresponding diastereoisomeric spirocyclic compounds 10 and 11, 12 and 13, 15 and 16, and 18 and 19, respectively (Schemes 4–7). In the reaction of 14 with 6, the 1,3‐oxathiolane 20 with a Ph group at C(2) was also formed. The structures of 3, 7, 8, 10, 19, and 20 were established by X‐ray crystallography (Figs. 1–4). In contrast to the thiolactones 1, 9, and 14, the thioesters 21a–21d did not react with (R)‐2‐phenyloxirane (6) either in the presence of SiO2 or under more‐drastic conditions with BF3⋅Et2O or SnCl4 (Scheme 8). The results show that spirocyclic 1,3‐oxathiolanes can be prepared from thiolactones with oxiranes. The nucleophilic attack of the thiocarbonyl S‐atom at the SiO2‐activated oxirane ring proceeds with high regio‐ and stereoselectivity via an SN2‐type mechanism.
Chiral Borate Esters in Asymmetric Synthesis. Part 2
Authors: Liu Dejun , Shan Zixing , Zhou Yan , Wu Xiaojun , Qin Jingui
Published: September 2004

Asymmetric catalytic activity of the chiral spiroborate esters 1–9 with a O3BN framework (see Fig. 1) toward borane reduction of prochiral ketones was examined. In the presence of 0.1 equiv. of a chiral spiroborate ester, prochiral ketones were reduced by 0.6 equiv. of borane in THF to give (R)‐secondary alcohols in up to 92% ee and 98% isolated yields (Scheme 1). The stereoselectivity of the reductions depends on the constituents of the chiral spiroborate ester (Table 2) and the structure of the prochiral ketones (Table 1). The configuration of the products is independent of the chirality of the diol‐derived parts of the catalysts. A mechanism for the catalytic behavior of the chiral spiroborate esters (R,S)‐2 and (S,S)‐2 during the reduction is also suggested.
New Protected Protecting Groups for the 5′‐Hydroxy Group of Deoxynucleosides by Use of 2‐(Hydroxymethyl)‐ and 2‐[(Methylamino)methyl]benzoyl Skeletons and Oxidatively Cleavable Tritylthio and (4‐Methoxytrityl)thio Groups
Authors: Seio Kohji , Utagawa Eri , Sekine Mitsuo
Published: September 2004

The new protecting groups 1a,b and 2a,b were developed for the 5′‐OH group of deoxynucleosides by utilizing the unique characters of the sulfenate and sulfenamide linkage. These new protecting groups have a 2‐(hydroxymethyl)benzoyl or 2‐[(methylamino)methyl]benzoyl skeleton whose hydroxy O‐atom or amino N‐atom was blocked with a tritylthio‐type substituent. They are removable by intramolecular cyclization following the oxidative hydrolysis of the tritylthio‐type substituents under mildly oxidative conditions (Schemes 3 and 6). Among them, 2‐{{[(4‐methoxytrityl)sulfenyl]oxy}methyl}benzoyl (MOB; 2b) was found to be the most preferable for protection of the 5′‐OH function of deoxynucleosides. MOB can be introduced at the 5′‐OH groups of various deoxynucleosides without the protection of the 3′‐OH functions (Scheme 5). The applicability of the MOB group to a new oligodeoxynucleotide synthesis protocol without acid treatment was demonstrated by the solid‐phase synthesis of a tetrathymidylate (Scheme 8).
Inhibitors Designed for Presenilin 1 by Means of Aspartic Acid Activation. Preliminary Communication
Authors: Larbig Gregor , Zall Andrea , Schmidt Boris
Published: September 2004

γ‐Secretase, a multiprotein aspartic protease crucial to Alzheimer's dementia, is not available for NMR experiments and has, so far, escaped crystallization. A positional scan of the aspartic protease by reactive probes may provide the necessary structural information for drug development. We describe here the synthesis of acid‐labile compounds based on the known inhibitor DAPT (1), e.g., the N‐terminally functionalized diazo compound 4 or the C‐terminally acid‐labile (cyclopropylmethyl)ester 11, which were designed to react in the specific acidic active‐site environment of the aspartic protease presenilin 1. The acid‐labile DAPT analogues 11–13, indeed, displayed strong inhibition in a cell‐free γ‐secretase assay.
Junceellonoids A and B, Two New Briarane Diterpenoids from the Chinese Gorgonian Junceella fragilisRidley
Authors: Zhang When , Guo Yue‐Wei , Mollo Ernesto , Cimino Guido
Published: September 2004

Two new diterpenoids, junceellonoids A and B (1 and 2, resp.), together with the seven known diterpenoids 3–9, all possessing the briarane carbon skeleton, were isolated from the gorgonian Junceella fragilis Ridley, collected in the South Sea of China. The structures and relative configurations of the new metabolites were elucidated based on extensive spectral analysis and by comparison with known spectral data.
Abietanes and a Novel 20‐Norabietanoid from Plectranthus cyaneus (Lamiaceae)
Authors: Horvath Tibor , Linden Anthony , Yoshizaki Fumihiko , Eugster Conrad Hans , Rüedi Peter
Published: September 2004

Antioxidative‐activity‐guided fractionation of extracts of the aerial parts of the title plant yielded the two novel abietanoid diterpenoids 11,20‐dihydroxysugiol (=11,12,20‐trihydroxyabieta‐8,11,13‐trien‐7‐one; 3) and 1,11‐epoxy‐6,12‐dihydroxy‐20‐norabieta‐1(10),5,8,11,13‐pentaen‐7‐one (4) in addition to 11‐hydroxysugiol (=12‐O‐demethylcryptojaponol=11,12‐dihydroxyabieta‐8,11,13‐trien‐7‐one; 2) and the main constituent carnosolon (=6,20‐epoxy‐6,11,12‐trihydroxyabieta‐8,11,13‐trien‐7‐one; 1). The structures were established on the basis of spectroscopic, chiroptic, and X‐ray crystallographic evidence.
Versatile One‐Step One‐Pot Direct Aldol Condensation Promoted by MgI2
Authors: Wei Han‐Xun , Li Kunyu , Zhang Qian , Jasoni Richard L. , Hu Jiali , Paré Paul W.
Published: September 2004

A true one‐step one‐pot aldol‐reaction procedure has been developed for the synthesis of β‐hydroxy ketones and esters. The reaction can be run at room temperature by simply mixing four components in CH2Cl2, with medium‐to‐high yields of aldol products obtained after regular workup. Mechanistically, the process probably proceeds via Mg‐enolate formation of the ketone or ester component, followed by addition to the electrophilic aldehyde.
Synthesis of Substituted α‐(Hydroxymethyl)‐β‐iodoacrylates via MgI2‐Promoted Stereoselective Aldol Coupling
Authors: Wei Han‐Xun , Hu Jiali , Jasoni Richard L. , Li Guigen , Paré Paul W.
Published: September 2004

The efficient and highly stereoselective syntheses of a variety of (Z)‐configured, substituted α‐(hydroxymethyl)‐β‐iodo‐acrylates from prop‐2‐ynoate and various aldehydes was achieved. The synthetic protocol involves a simple one‐pot coupling reaction under mild conditions, promoted by MgI2, which serves both as a Lewis acid and iodine source for a BaylisHillman‐type reaction. All adducts were generated in good‐to‐excellent yields, the (Z)‐isomers being formed in high selectivity (>98%). The conversion of methyl prop‐2‐ynoate into an active ‘β‐iodo allenolate’ intermediate, which then nucleophilically attacks an aldehyde, is proposed as a plausible reaction mechanism.
Cyclotrimerization of ‘Oxabenzonorbornadiene’: Synthesis of syn‐ and anti‐5,6,11,12,17,18‐Hexahydro‐5,18:6,11:12,17‐triepoxytrinaphthylene
Authors: De Lucchi Ottorino , Daştan Arif , Altundaş Aliye , Fabris Fabrizio , Balci Metin
Published: September 2004

An efficient synthetic route to the concave‐shaped, potentially ionophoric syn‐ and anti‐isomers of 5,6,11,12,17,18‐hexahydro‐5,18:6,11:12,17‐triepoxytrinaphthylene (4) was elaborated. Starting from ‘oxabenzonorbornadiene’ (5), the stannylated precursor 9 was prepared in three steps, followed by cyclotrimerization catalyzed by copper(I) thiophene‐2‐carboxylate (CuTC) , which afforded 4 in a syn/anti ratio of 5 : 4.
Circular‐Dichroism Studies on Artemisinin and Epiartemisinin and Their β‐Cyclodextrin Complexes in Solution
Authors: Marconi Giancarlo , Monti Sandra , Manoli Francesco , Degli Esposti Alessandra , Guerrini Andrea
Published: September 2004

The circular dichroism (CD) spectra of the powerful antimalarian active principle artemisinin (ART; 1) from Artemisia annua, and of epiartemisinin (EPI, 2), its C(7) epimer, were studied in solution in the presence and absence of β‐cyclodextrin (β‐cd). A significant inversion of sign in the region of the second electronic transition was detected. The rotational strengths were successfully calculated within the time‐dependent density functional theory (DFT), which enabled us to establish a correlation between the molecular recognition and the biological acitivities of the two isomers.
Azirine/Oxindole Ring Enlargement via Amidinium Intermediates
Authors: Mekhael Maged K. G. , Bienz Stefan , Linden Anthony , Heimgartner Heinz
Published: September 2004

A novel general method for the synthesis of oxindoles, namely the ‘azirine/oxindole ring enlargement via amidinium‐intermediates’ has been established: the reaction of 2H‐azirin‐3‐amines 1 with BF3⋅OEt2 in THF solution at −78° leads to 1,3,3‐trialkyl‐2‐amino‐3H‐indolium tetrafluoroborates 14 in good yields (Scheme 5). Treatment of aqueous solutions of 14 at 0° with aqueous NaOH (30%) and extraction with CH2Cl2 gives oily substances that are either hydrates of 1,3,3‐trialkyl‐2‐dihydroindol‐2‐imines 15 or the corresponding indolium hydroxides. These products are transformed to the corresponding 1,3,3‐trialkyl‐2,3‐dihydroindol‐2‐ones 17 in modest yields upon refluxing in H2O/THF. Reaction of 14 with Ac2O in pyridine at ca. 23° for 16 h followed by aqueous workup and chromatographic separation leads to mixtures of N‐(1,3,3‐trialkyl‐2,3‐dihydro‐indol‐2‐yliden)acetamides 16 and oxindoles 17 (Scheme 6). Hydrolysis of 16 with aqueous HCl under reflux for 1–2 h gives oxindoles 17 in a good yield. Several oxindoles, spiro‐oxindoles, and 5‐substituted oxindoles were synthesized by means of the reactions mentioned above.
Synthesis and Oxidation of N‐Aminoglyconolactams: A Synthesis of Mannostatin A
Authors: Hu Guixian , Vasella Andrea
Published: September 2004

The N‐amino‐ribono‐1,5‐lactam 4 was prepared in two high‐yielding steps from the known methanesulfonate 2. Oxidation of 4 with t‐BuOCl in the presence of 2,6‐lutidine afforded the tetrazene 6 (63%). Oxidation with MnO2 gave the deaminated lactam 7 (40%), which was also obtained, together with the lactone 8, upon oxidation of 4 with PhSeO2H. Oxidation with Mn(OAc)3/Cu(OAc)2 provided the lactam 7 as the major and the dimer 9 as the minor product. Oxidation of 4 with 3 equiv. of Pb(OAc)4 in toluene at room temperature gave two cyclopentanes, viz. the acetoxy epoxide 10 and the diazo ketone 11 in a combined yield of 78%. Oxidation with Pb(OBz)4 provided 11 and the crystalline benzoyloxy epoxide 12. The crystal structure of 12 was established by X‐ray analysis. The N‐amino‐glyconolactams 41, 46, and 51 were prepared similarly to 4. Their oxidation with Pb(OAc)4 provided the diazo ketones 56, 57, and 58 as the only isolable products. Oxidation of the N‐amino‐mannono‐1,5‐lactam 55 with Pb(OAc)4 in the presence of DMSO gave the sulfoximine 59. Mannostatin A, a strong α‐mannosidase inhibitor, was synthesized from the acetoxy epoxide 10 (obtained in 48% from 4) in seven steps and in an overall yield of 45%.
Cyclopentanes from N‐Aminoglyconolactams: Reaction Mechanism and Improved Access to Diazocyclopentanones
Authors: Hu Guixian , Vasella Andrea
Published: September 2004

One of the two mechanisms to rationalize the Pb(OAc)4 oxidation of 1 to 2 and 3 postulates the intermediate generation of a carbene 25 via the acetoxy‐diazepinone 22 and the oxadiazoline 23 (Scheme 2). This mechanism was excluded on the basis of the oxidation of the diazepinone 32 that was synthesized in six steps from the ribonolactone 26. Oxidation of 32 with Pb(OAc)4 provided the unstable acetoxy‐diazepinone intermediate 22, its C(5) epimer, and the stable 5‐O‐acetyl‐1,5‐ribonolactone 33; the 1H‐NMR spectra of the products of the oxidation of 32 and the decomposition of 22 showed no evidence for the formation of the acetoxy epoxide 2 and the diazo ketone 3, excluding 22 as intermediate in the oxidation of 1. To increase the yield of the diazo‐cyclopentanones, we oxidized the acetohydrazide 34, the 4‐toluenesulfonohydrazide 44, and the N,O‐diacetate 46 with Pb(OAc)4. Oxidation of the acetohydrazide 34 with Pb(OAc)4 led to a higher yield of the diazo ketone 3 (40%) than oxidation of the N‐amino‐ribonolactam 1 without affecting the yield of 2. Oxidation of the 4‐toluenesulfonohydrazide 44 gave mostly the product 45 of C‐acetoxylation, while the analogous oxidation of 46 gave the acetoxy lactone 33; neither 2 nor 3 could be detected among the products, excluding 46 as intermediate of the oxidation of 34. Oxidation of the N‐acetamido‐lyxonolactam 47 with Pb(OAc)4 provided the diazo ketone 8 (77 vs. 37% from 5); higher yields of diazo ketones resulted also from the oxidation of the acetohydrazides 48 and 49.
Design of an Intercalating Linker Leading to the First Efficiently 5′,5′‐Linked Alternate‐Strand Hoogsteen Triplex with High Stability and Specificity
Authors: Jessen Carsten H. , Pedersen Erik B.
Published: September 2004

This is the first report describing the design, synthesis, and incorporation of an intercalating linker leading to an efficiently 5′,5′‐linked alternate strand Hoogsteen triplex. Using molecular modeling, the 5′,5′ problem was solved in a rather simple way. The two relatively distant 5′‐ends have been connected with a molecule that provides rigidity to the structure, while being flexible enough to allow stacking upon all four strands. The synthesis of the core of the designed molecule was conducted by Sonogashira coupling of an appropriately substituted iodobenzene with 1,3‐diethynylbenzene to give a conjugated system with three benzene rings interconnected with triple bonds. For the alternate‐strand triplex obtained with the intercalating linker, the stability obtained is higher than that of the corresponding homotriplex of equivalent total length and with the same nucleotides. This is deduced from a 5° higher melting temperature of the alternating triplex. The sensitivity towards mismatches in the alternate‐strand triplex is in the same range (ΔTm=−13° to −19°) as those observed for homotriplexes.
Epstein‐Barr virus latent membrane 2A (LMP2A) down‐regulates telomerase reverse transcriptase (hTERT) in epithelial cell lines
Authors: Chen Fu , Liu Cheng , Lindvall Charlotta , Xu Dawei , Ernberg Ingemar
Published: September 2004

The latent membrane protein (LMP) 2A, one of the membrane‐spanning polypeptides encoded by the Epstein‐Barr virus (EBV), has been implicated in the maintenance of viral latency and appears to function in part by inhibiting B‐cell receptor (BCR) signaling through its ITAM motifs. It has also been suggested that LMP2A is involved in tumorigenesis mediated by EBV. In our study, we determined regulatory effects of LMP2A on the telomerase reverse transcriptase (hTERT) expression. We observed a significant and constant reduction of hTERT mRNA accompanied by decreased telomerase activity in epithelial cells expressing LMP2A. It was further shown that LMP2A inhibited the hTERT promoter activity in transient transfections of both B cells and epithelial cells, and that the ITAM motif was required for this inhibition. Thus LMP2A expression leads to the transcriptional repression of the hTERT gene through specific pathways, which may thereby contribute to the control of EBV‐latency.
Regulation of the multidrug resistance transporter P‐glycoprotein in multicellular prostate tumor spheroids by hyperthermia and reactive oxygen species
Authors: Wartenberg Maria , Gronczynska Sabina , Bekhite Mohamed M. , Saric Tomo , Niedermeier Wilhelm , Hescheler Jürgen , Sauer Heinrich
Published: September 2004

Hyperthermia is an important component of many cancer treatment protocols. In our study the regulation of the multidrug resistance (MDR) transporter P‐glycoprotein by hyperthermia was studied in multicellular prostate tumor spheroids. Hyperthermia treatment of small (50–100 μm) tumor spheroids significantly increased P‐glycoprotein and mdr‐1 mRNA expression with a maximum effect at 42°C, whereas only moderate elevation of P‐glycoprotein was found in large (350–450 μm) tumor spheroids. Hyperthermia caused an elevation of intracellular reactive oxygen species (ROS). Inhibition of ROS generation with NADPH‐oxidase inhibitors diphenylen iodonium (DPI) and 4‐(2‐aminoethyl)benzenesulfonyl fluoride (AEBSF) abolished P‐glycoprotein expression but did not affect its transcript levels following heat treatment. This indicates that P‐glycoprotein levels are controlled by regulating its translation rate or stability. Hyperthermia incubation resulted in a differential activation of p38 mitogen‐activated protein kinase (MAPK), extracellular regulated kinase 1,2 (ERK1,2), and c‐jun N‐terminal kinase (JNK) immediately, 4 hr and 24 hr after treatment. Furthermore, upregulation of hypoxia‐inducible factor 1α (HIF‐1α) was observed. Elevation of HIF‐1α and P‐glycoprotein expression following hyperthermia treatment were abolished upon coadministration of the p38 inhibitor SB203580. In contrast the JNK inhibitor SP600125 and the ERK1,2 inhibitor UO126 resulted in increase of HIF‐1α and P‐glycoprotein in the control as well as the hyperthermia‐treated samples, indicating negative regulation of intrinsic HIF‐1α and P‐glycoprotein expression by ERK1,2 and JNK signaling cascades. In summary our data demonstrate that hyperthermia‐induced upregulation of P‐glycoprotein and HIF‐1α is mediated by activation of p38, whereas ERK1,2 and JNK are involved in repression of P‐glycoprotein and HIF‐1α under control conditions.
Preoperative genetic diagnosis of gastric carcinoma based on chromosomal loss and microsatellite instability
Authors: Hong Seung‐Jin , Choi Sang‐Wook , Lee Kang‐Hoon , Lee Sung , Min Ki‐Ouk , Rhyu Mun‐Gan
Published: September 2004

The degree of chromosomal losses and the presence of microsatellite instability (MSI) in gastric carcinomas have been categorized into low‐risk (low‐level loss and MSI) and high‐risk (baseline‐ and high‐level losses) genotypes. With the aim of making a preoperative diagnosis, this study confirmed the stem line genotype that is common over an entire tumor as well as in a single biopsy specimen. Biopsy specimens were obtained from 91 gastric carcinoma patients and examined for their microsatellite genotypes using a panel of 41 microsatellite markers on 8 cancer‐associated chromosomes. The genotype of the biopsy specimens was compared with that of a surgical specimen, which had been multifocally examined for its intratumoral heterogeneity. Of the 91 pairs of biopsy and surgical specimens, 87 (96%) containing either the same (60 cases) or a similar (17 cases) number of chromosomal losses were categorized into the same microsatellite genotype, and the remaining 4 pairs (4%) were classified into a different genotype. The surgical specimens showed that an extraserosal invasion and lymph node metastasis are frequently associated with either a high‐level (4 or more) of chromosomal losses irrespective of the tumor size (73% and 85%) or the large carcinomas > 5 cm in diameter irrespective of the tumor genotype (76% and 83%). The status of the extraserosal invasion and lymph node metastasis (0.691 and 0.802 receiver operating characteristic areas, respectively) predicted by the biopsy genotype and the tumor size corresponded closely to the surgical pathology results. Therefore, the extent of chromosomal losses and the presence of an MSI determined on a biopsy specimen will provide valuable information for making a preoperative genetic diagnosis of a gastric carcinoma.
Expression of prostate‐specific antigen (PSA) and human glandular kallikrein 2 (hK2) in ileum and other extraprostatic tissues
Authors: Olsson A. Yvonne , Bjartell Anders , Lilja Hans , Lundwall Åke
Published: September 2004

Prostate‐specific antigen (PSA) is a widely used marker for prostate cancer. In the literature, there are reports of nonprostatic expression of PSA that potentially can affect early diagnosis. However, the results are scattered and inconclusive, which motivated us to conduct a more comprehensive study of the tissue distribution of PSA and the closely related protein human glandular kallikrein 2 (hK2). RT‐PCR, in situ hybridization and immunohistochemistry were used to detect expression of both PSA and hK2 in secretory epithelial cells of trachea, thyroid gland, mammary gland, salivary gland, jejunum, ileum, epididymis, seminal vesicle and urethra, as well as in Leydig cells, pancreatic exocrine glands and epidermis. Immunometric measurements revealed that the concentration of PSA in nonprostatic tissues represents less than 1% of the amount in normal prostate. Pronounced expression of PSA was detected in the Paneth cells in ileum, which prompted us to compare functional parameters of PSA in ileum and prostate. We found that in homogenates from these 2 tissues, PSA manifested equivalent amidolytic activity and capacity to form complexes with protease inhibitors in blood in vitro. Thus, PSA released from sources other than the prostate may add to the plasma pool of this protein, but given the lower levels detected from those sites, it is unlikely that nonprostatic PSA normally can interfere with the diagnosis of prostate cancer. Nevertheless, this risk should not be neglected as it may be of clinical significance under certain circumstances. Supplementary material for this article can be found on the International Journal of Cancer website at http://www.interscience.wiley.com/jpages/0020‐7136/suppmat/index.html.
Electrospinning of gelatin fibers and gelatin/PCL composite fibrous scaffolds
Authors: Zhang Yanzhong , Ouyang Hongwei , Lim Chwee Teck , Ramakrishna Seeram , Huang Zheng‐Ming
Published: September 2004

In this article, ultrafine gelatin (Gt) fibers were successfully produced with the use of the electrical spinning or electrospinning technique. A fluorinated alcohol of 2,2,2‐trifluoroethanol (TFE) was used as the dissolving solvent. The morphology of the electrospun gelatin fibers was found to be dependent on the alteration of gelatin concentration ranging from 2.5% w/v to 12.5% w/v at 2.5% increment intervals. Based on the electrospun gelatin fibers obtained, 10% w/v gelatin/TFE solution was selected and mixed with 10% w/v poly(ϵ‐caprolactone) (PCL) in TFE at a ratio of 50:50 and co‐electrospun to produce gelatin/PCL composite membranes. Contact‐angle measurement and tensile tests indicated that the gelatin/PCL complex fibrous membrane exhibited improved mechanical properties as well as more favorable wettability than that obtained from either gelatin or PCL alone. The gelatin/PCL fibrous membranes were further investigated as a promising scaffold for bone‐marrow stromal cell (BMSC) culture. Scanning electron microscopy (SEM) and laser confocal microscopy observations showed that the cells could not only favorably attach and grow well on the surface of these scaffolds, but were also able to migrate inside the scaffold up to 114 μm within 1 week of culture. These results suggest the potential of using composite gelatin/PCL fibrous scaffolds for engineering three‐dimensional tissues. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 72B: 156–165, 2005
Calcium sulfate: Analysis of MG63 osteoblast‐like cell response by means of a microarray technology
Authors: Carinci Francesco , Piattelli Adriano , Stabellini Giordano , Palmieri Annalisa , Scapoli Luca , Laino Gregorio , Caputi Sergio , Pezzetti Furio
Published: September 2004

Calcium sulfate (CaS) is an highly biocompatible material that has the characteristic of being one of the simplest as well as one of the synthetic bone‐like graft with the longest clinical history, spanning more than 100 years. Solidified or crystallized CaS is very osteogenic in vivo. As the surface CaS dissolves in body fluid, the calcium ions form calcium phosphate that reprecipitates on the surface forming an osteoblast “friendly” environment. How this “friendly” environment alters osteoblast activity to promote bone formation is poorly understood. We therefore attempted to address this question by using microarray techniques to identified genes that are differently regulated in osteoblasts exposed to CaS. By using DNA microarrays containing 19,200 genes, we identified in osteoblast‐like cells line (MG‐63) cultured with CaS (Surgiplaster, Classimplant, Roma, Italy) several genes that expression was significantly upregulated. The differentially expressed genes cover a broad range of functional activities: (a) immunity, (b) lysosomal enzymes production, (c) cell cycle regulation, (d) and signaling transduction. It was also possible to detect some genes whose function is unknown. The data reported are, to our knowledge, the first genetic portrait of CaS effects. They can be relevant to better understand the molecular mechanism of bone regeneration and as a model for comparing other materials with similar clinical effects. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 71B: 260–267, 2004
Fast topological analysis of 2D and 3D grids of data: Application to the atoms in molecule (AIM) and the electron localization function (ELF)
Authors: Soler Philippe , Fuster Franck , Chevreau Hilaire
Published: September 2004

The topological analysis of grids of data is used for determination of surfaces or volumes around maxima. The volumes are then related to chemical information such as atoms or bonds, and can be used for integration of local properties such as electronic population. The problem of global connectivity is reversed into the question of local connectivity yielding a linear scaling partition algorithm. Two packages are developed for a very fast analysis and partition of 2D or 3D grids of data, applications being made to C2H2, C2H4, C6H6, H2CO, and H2CS molecules using the Atoms in Molecule (AIM) or Electron Localization Function (ELF). © 2004 Wiley Periodicals, Inc. J Comput Chem 25: 1920–1925, 2004
A polynomial version of the generator coordinate Dirac–Fock method
Authors: Haiduke Roberto L. A. , De Macedo Luiz G. M. , Barbosa Rugles C. , Da Silva Albérico B. F.
Published: September 2004

A polynomial version of the Generator Coordinate Dirac–Fock (p‐GCDF) method is introduced and applied to develop Adapted Gaussian Basis Sets (AGBS) for helium‐ and beryllium‐like atomic species (He, Ne+8, Ar+16, Sn+48, Be, Ne+6, Ar+14, and Sn+46) and for Kr and Xe atoms. The Dirac–Fock–Coulomb and Dirac–Fock–Breit energies obtained with these basis sets are in excellent agreement with numerical finite‐difference calculations. Moreover, the sizes of the AGBS generated here with the p‐GCDF method are significantly smaller than the size of previous relativistic Gaussian basis sets. © 2004 Wiley Periodicals, Inc. J Comput Chem 25: 1904–1909, 2004
Interconversion behavior of the CH bond in the CH radical cation: Ab initio molecular dynamics study
Authors: Ohta Yasuhito , Ohta Koji
Published: September 2004

Thermal motion of CH is investigated by performing an ab initio molecular dynamics method with the second‐order Møller‐Plesset (MP2)/6‐311G** force field. In the trajectories obtained at 400 K, we have observed rapid interconversion behavior of the geometrical parameters of CH with the frequency of 0.6/ps, where the CH pair forming the small angle around 55° is switched to another pair on subpicosecond time scale. The switching patterns are found to be classified into the following two types. Type 1: one CH of the small angled CH pair is switched to one CH of the other CH pair. Type 2: the small angled CH pair is switched to the other CH pair, which has been newly observed in the present ab initio MD calculation. The four CH bonds of CH are characterized by the long and short CH bonds in a time region of the trajectories, and also for the time‐evolution of CH bonds such interconversion behavior is observed. The switching patterns of the geometrical parameters are compared with those in the interconversion scheme between six equivalent C2v symmetry structures of CH [Paddon‐Row, M. N. et al., J Am Chem Soc 1985, 107, 7696]. We have also investigated the electronic energy fluctuation due to thermal motion of CH. The standard deviation of total electronic energy at 400 K is evaluated to be 1.2 kcal/mol. © 2004 Wiley Periodicals, Inc. J Comput Chem 15: 1910–1919, 2004
OCTN3: A Na+‐independent L‐carnitine transporter in enterocytes basolateral membrane
Authors: Durán J.M. , Peral M.J. , Calonge M.L. , Ilundáin A.A.
Published: September 2004

L‐carnitine transport has been measured in enterocytes and basolateral membrane vesicles (BLMV) isolated from chicken intestinal epithelia. In the nominally Na+‐free conditions chicken enterocytes take up L‐carnitine until the cell to medium L‐carnitine ratio is 1. This uptake was inhibited by L‐carnitine, D‐carnitine, γ‐butyrobetaine, acetylcarnitine, tetraethylammonium (TEA), and betaine. L‐3H‐carnitine uptake into BLMV showed no overshoot, and it was (i) Na+‐independent, (ii) trans‐stimulated by intravesicular L‐carnitine, and (iii) cis‐inhibited by TEA and cold L‐carnitine. L‐3H‐carnitine efflux from L‐3H‐carnitine preloaded enterocytes was also Na+‐independent, and trans‐stimulated by L‐carnitine, D‐carnitine, γ‐butyrobetaine, acetylcarnitine, TEA, and betaine. Both, uptake and efflux of L‐carnitine were inhibited by verapamil and unaffected by either extracellular pH or palmitoyl‐L‐carnitine. RT‐PCR with specific primers for the mouse OCTN3 transporter revealed the existence of OCTN3 mRNA in mouse intestine, which was confirmed by in situ hybridization studies. Immunohystochemical analysis showed that OCTN3 protein was mainly associated with the basolateral membrane of rat and chicken enterocytes, whereas OCTN2 was detected at the apical membrane. In conclusion, the results demonstrate for the first time that (i) mammalian small intestine expresses OCTN3 mRNA along the villus and (ii) that OCTN3 protein is located in the basolateral membrane. They also suggest that OCTN3 could mediate the passive, Na+ and pH‐independent L‐carnitine transport activity measured in the three experimental conditions. © 2004 Wiley‐Liss, Inc.
Regulation of Indian hedgehog mRNA levels in chondrocytic cells by ERK1/2 and p38 mitogen‐activated protein kinases
Authors: Lai Lick Pui , DaSilva Kevin A. , Mitchell Jane
Published: September 2004

Indian hedgehog (Ihh) is produced by growth plate pre‐hypertrophic chondrocytes, and is an important regulator of endochondral ossification. However, little is known about the regulation of Ihh in chondrocytes. We have examined the role of integrins and mitogen‐activated protein (MAP) kinases in Ihh mRNA regulation in CFK‐2 chondrocytic cells. Cells incubated with the β1‐integrin blocking antibody had decreased Ihh mRNA levels, which was accompanied by decreases of activated extracellular signal‐regulated kinases (ERK1/2) and activated p38 MAPK. Ihh mRNA levels were also inhibited by U0126, a specific MEK1/2 inhibitor, or SB203580, a specific p38 MAPK inhibitor. Cells transfected with constitutively active MEK1 or MKK3 had increased Ihh mRNA levels, which were diminished by dominant‐negative MEK1, p38α or p38β. Stimulation of the PTH1R with 10−8 M rPTH (1–34) resulted in dephosphorylation of ERK1/2 that was evident within 15 min and sustained for 1 h, as well as transient dephosphorylation of p38 MAPK that was maximal after 25 min. PTH stimulation decreased Ihh mRNA levels, and this effect was blocked by transfecting the cells with constitutively active MEK1 but not by MKK3. These studies demonstrated that activation of ERK1/2 or p38 MAPK increased Ihh mRNA levels. Stimulation of the PTH1R or blocking of β1‐integrin resulted in inhibition of ERK1/2 and p38 MAPK and decreased levels of Ihh mRNA. Our data demonstrate the central role of MAPK in the regulation of Ihh in CFK‐2 cells. © 2004 Wiley‐Liss, Inc.
Laminopathies: Involvement of structural nuclear proteins in the pathogenesis of an increasing number of human diseases
Authors: Maraldi Nadir M. , Squarzoni Stefano , Sabatelli Patrizia , Capanni Cristina , Mattioli Elisabetta , Ognibene Andrea , Lattanzi Giovanna
Published: September 2004

Just at the beginning of the millennium the neologism laminopathies has been introduced in the scientific vocabulary. An exponential increase of interest on the subject started concomitantly, so that a formerly quite neglected group of rare human diseases is now widely investigated. This review will cover the history of the identification of the molecular basis for fourteen (since now) hereditary diseases arising from defects in genes that encode nuclear envelope and nuclear lamina‐associated proteins and will also consider the hypotheses that can account for the role of structural nuclear proteins in the pathogenesis of diseases affecting a wide spectrum of tissues. © 2004 Wiley‐Liss, Inc.