bluuebunny/crossref_metadata_2025_split huggingface dataset:
Expanding the Scope and Orthogonality of PNA Synthesis
Authors: Pothukanuri Srinivasu , Pianowski Zbigniew , Winssinger Nicolas 
Published: May 2008

AbstractPeptide nucleic acids (PNAs) hybridize to natural oligonucleotides according to Watson and Crick base‐pairing rules. The robustness of PNA oligomers and ease of synthesis have made them an attractive platform to encode small or macromolecules for microarraying purposes and other applications based on programmable self assembly. A cornerstone of these endeavors is the orthogonality of PNA synthesis with other chemistries. Herein, we present a thorough investigation of six types of protecting groups for the terminal nitrogen atom (Alloc, Teoc, 4‐N3Cbz, Fmoc, 4‐OTBSCbz, and Azoc) and five protecting groups on the nucleobases (Cl‐Bhoc, F‐Bhoc, Teoc, 4‐OMeCbz, and Boc). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
1‐Aryl‐3,3‐diisopropyltriazenes: An Easily Accessible and Particularly Stable Class of Triazenes Towards Strong Basic and Lewis Acid Conditions
Authors: Reingruber Rüdiger , Vanderheiden Sylvia , Wagner Alfred , Nieger Martin , Muller Thierry , Es‐Sayed Mazen , Bräse Stefan 
Published: May 2008

AbstractThe stability of various substituted aryl‐3,3‐dialkyltriazenes, valuable synthetic intermediates, under several reaction conditions has been evaluated. To do so, anthranilonitrile and 2‐amino‐6‐(trifluoromethyl)benzonitrile have been reacted in the presence of different secondary amines to the corresponding 1‐(2‐R‐phenyl)‐3,3‐dialkyltriazenes. These compounds have been submitted to a series of different reaction conditions with special emphasis on strong basic and metal/acid reductive conditions in order to test the stability of the triazene moiety under these circumstances. Generally, triazenes are unstable in metal/acid reducing conditions. A lot of 1‐aryl‐3,3‐dialkyltriazenes are known to undergo deprotonation in α‐position of N‐3 in the presence of strong bases, thus limiting the scope of action of this class of compounds. Among the tested substances, most triazenes were stable in the presence of titanium isopropoxide and/or strong nucleophiles. 1‐(2‐R‐phenyl)‐3,3‐diisopropyltriazenes turned out to be particularly stable under strong basic conditions. 1,2‐addition reactions in the presence of Grignard reagents or lithiated compounds, showed in most cases no side products resulting from a degradation of the triazene function. The same was true for the titanium‐catalyzed Kulinkovich–de Meijere cyclopropanation or for reductive amination. In both cases, no triazene degradation products could be detected. 1‐(2‐R‐phenyl)‐3,3‐diisopropyltriazenes were even stable in the presence of strong Lewis acids like trimethylaluminium. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Reactions of Nitrosoarenes with Nitrogen Monoxide (Nitric Oxide) and Nitrogen Dioxide: Formation of Diarylnitroxides
Authors: Astolfi Paola , Carloni Patricia , Damiani Elisabetta , Greci Lucedio , Marini Milvia , Rizzoli Corrado , Stipa Pierluigi 
Published: May 2008

AbstractNitrosoarenes react with nitrogen monoxide (nitric oxide) at room temperature and in aprotic media to afford the corresponding diarylnitroxides by the intermediate formation of N‐nitrosoarylnitroxides. However, these latter spin adducts, in contrast with literature reports, have never been detected by us. N‐nitrosophenylnitroxide is obtained only in the oxidation of the ammonium salt of N‐nitrosophenylhydroxylamine (cupferron) with trace amounts of lead tetraacetate. However, it evolves with time to diphenylnitroxide, as demonstrated by following the reaction course in the ESR cavity. On a macroscale level, the reaction between nitrosobenzene and nitric oxide leads to the formation of N‐nitrosodiphenylamine, 4‐nitro‐N‐nitrosodiphenylamine, 4‐nitrodiphenylamine and 4,4′‐dinitrodiphenylamine, in addition to diphenylnitroxide. Diarylnitroxides are also obtained when nitrosoarenes react with small amounts of nitrogen dioxide; the mechanism of this reaction is proposed and discussed. The structure of 4‐nitro‐N‐nitrosodiphenylamine was determined by X‐ray analysis.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Reactions of Carbenes with Ethers: The Role of Noncovalent Interactions
Authors: Mieusset Jean‐Luc , Brinker Udo H. 
Published: May 2008

AbstractThe influence of ethers upon carbenes has been investigated computationally by the B3LYP, MP2, and MPWB1K methods. Ylide formation is only obtained with reactive‐electrophilic carbenes like cyclopentadienylidene, whereas more nucleophilic carbenes like cyclopent‐2‐enylidene associate by interactions of lone pairs of carbon and oxygen atoms with C–H bonds. Between the stabilized‐electrophilic dichlorocarbene and the oxygen lone pairs, only weak complexes are formed. Furthermore, the mechanism of the C–H insertion of dichlorocarbene into bicyclic ethers containing a three‐membered ring has been explored. The experimental data confirm the computational results. The insertion occurs easily into the α‐position of the oxygen atom in secondary ethers but not into the methyl group of methyl ethers. In all cases, insertion into the α‐position of a cyclopropane ring is not competitive.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Microwave‐Assisted Rhodium‐Complex‐Catalyzed Cascade Decarbonylation and Asymmetric Pauson–Khand‐Type Cycli­zations
Authors: Lee Hang Wai , Lee Lai Na , Chan Albert S. C. , Kwong Fuk Yee 
Published: May 2008

AbstractMicrowave‐assisted Rh–diphosphane‐complex‐catalyzed dual catalysis is reported. This cooperative process provides [2+2+1] cycloadducts by sequential decarbonylation of aldehyde or formate and carbonylation of enynes within a short period of time. Various O‐, N‐, and C‐tethered enynes were transformed into the corresponding products in good yields. The first enantioselective version of this microwave‐accelerated cascade cyclization was realized. In the presence of chiral Rh‐(S)‐bisbenzodioxanPhos complex, the cyclopentenone products were achieved with ee values up to 90 %. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Evaluation of the measured seismic response of the Mexico City Cathedral
Authors: Rivera Darío , Meli Roberto , Sánchez Roberto , Orozco Bernardo 
Published: May 2008

AbstractThe seismic response of the Mexico City Cathedral built of very soft soil deposits is evaluated by using motions recorded in various parts of the structure during several moderate earthquakes. This unique set of records provides significant insight into the seismic response of this and other similar historic stone masonry structures.Free‐field ground motions are carefully compared in time and frequency domains with motions recorded at building basement. The dynamic characteristics of the structure are inferred from the earthquake records by using system identification techniques. Variation of seismic response for different seismic intensities is discussed. It is shown that, due to the soil–structure interaction, due to large differences between dominant frequencies of earthquake ground motions at the site and modal frequencies of vibration of the structure, and due to a particularly high viscous damping, seismic amplifications of ground motion in this and similar historic buildings erected on soft soil deposits are much smaller than that induced in most modern constructions. Nevertheless, earthquake records and analytical results show that several components of the structure such as its central dome and the bell towers may be subjected to local vibrations that significantly amplify ground motions. Overall, results indicate that in its present state the structure has an acceptable level of seismic safety. Copyright © 2008 John Wiley & Sons, Ltd.
A new family of generalized‐α time integration algorithms without overshoot for structural dynamics
Authors: KaiPing Yu 
Published: May 2008

AbstractA new family of generalized‐α (G‐α) algorithm without overshoot is presented by introducing seven free parameters into the single‐step three‐stage formulation for solution of structural dynamic problems. It is proved through finite difference analysis that these algorithms are unconditionally stable, second‐order accurate and numerical dissipation controllable. The comparison of the new G‐α algorithms with the commonly used G‐α algorithms shows that the newly developed algorithms have the advantage of eliminating the overshooting characteristics exhibited by the commonly used algorithms while their excellent property of dissipation is preserved. The numerical simulation results obtained using a single‐degree‐of‐freedom system and a two‐degree‐of‐freedom system to represent the character of typical large systems coincide well with the results of theoretical analyses. Copyright © 2008 John Wiley & Sons, Ltd.
Investigation of a combustible material in the fire of Hengyang merchant's building
Authors: Zong Ruowen , Zhang Xiaoqin , Li Songyang , Zeng Wenru , Liao Guangxuan 
Published: May 2008

AbstractAgaric, a kind of important combustible material in the fire of Hengyang merchant's building, was investigated using different experiment equipments. Its degradation and pyrolysis behavior were studied by means of thermogravimetric and kinetic analysis and pyrolysis gas chromatography–mass spectroscopy analysis. External radiation heat and internal heat were used to ignite the agaric. For external radiation ignition, a series of bench‐scale fire tests were done in cone calorimeter in accordance with ISO 5660. As for the internal heat ignition, a fire test was carried out in a full‐scale room in accordance with ISO 9705. Multi‐parameter measurement, including heat release rate (HRR), mass loss rate (MLR), temperature field and species concentration, has been accomplished. Meanwhile, the process of a full‐scale fire test was numerically simulated. The computational results were consistent with experiment data, which will lay down a good foundation for further study in fire reconstruction of the whole fire. Copyright © 2008 John Wiley & Sons, Ltd.
Monocyte chemoattractant protein-1 secreted by adipose tissue induces direct lipid accumulation in hepatocytes
Authors: Clément Sophie , Juge-Aubry Cristiana , Sgroi Antonino , Conzelmann Stéphanie , Pazienza Valerio , Pittet-Cuenod Brigitte , Meier Christoph A. , Negro Francesco 
Published: May 2008

Abstract

For many years, adipose tissue has been mainly considered as an inert reservoir for storing triglycerides. Since the discovery that adipocytes may secrete a variety of bioactive molecules (hormones, chemokines, and cytokines), an endocrine and paracrine role for white adipose tissue (WAT) in the regulation of energy balance and other physiological processes has been established, particularly with regard to brain and muscle. In contrast, little is known about the interactions of WAT with liver. Hence, we examined the effect of the secretory products of WAT on hepatocytes. Conditioned medium of human WAT explants induced significant steatosis in hepatocyte cell lines. Factor(s) responsible for the conditioned medium-induced steatosis were screened by a battery of blocking antibodies against different cytokines/chemokines shown to be secreted by WAT. In contrast to interleukin-8 and interleukin-6, the monocyte chemoattractant protein-1 was capable of inducing steatosis in hepatocytes in a time-dependent manner at concentrations similar to those found in conditioned medium. Incubation of conditioned medium with antimonocyte chemoattractant protein-1 antibodies prevented triglyceride accumulation. Investigation of the mechanism leading to the triglyceride accumulation showed that both a diminution of apolipoprotein B secretion and an increase in phosphoenolpyruvate carboxykinase messenger RNA may be involved.

Conclusion:

The monocyte chemoattractant protein-1 secreted by adipose tissue may induce steatosis not only recruiting macrophages but also acting directly on hepatocytes. (Hepatology 2008.)
Significant gene expression differences in histologically “Normal” liver biopsies: Implications for control tissue
Authors: Asselah Tarik , Bièche Ivan , Laurendeau Ingrid , Martinot-Peignoux Michelle , Paradis Valerie , Vidaud Dominique , Valla Dominique-Charles , Bedossa Pierre , Marcellin Patrick , Vidaud Michel 
Published: May 2008

Abstract

Gene expression technologies allow the analysis of gene networks whose expression is associated with specific pathological conditions compared with normal tissue. We hypothesized that histologically normal tissue obtained in different ways (percutaneous or surgical liver biopsies), usually used as normal controls in gene expression studies, could have different gene expression patterns. Group A comprised percutaneous liver biopsies in 14 patients with mildly elevated alanine aminotransferase in whom all causes of liver disease had been ruled out. Group B comprised 14 surgical liver biopsies of nontumoral livers. All 28 specimens were histologically normal. Real-time quantitative reverse-transcription polymerase chain reaction were used to compare the messenger RNA expression of 240 selected genes in these two groups. Expression of 26 of the 240 genes was significantly different between groups A and B; 23 genes were up-regulated in group A, while three were down-regulated in group B. The most notable changes occurred in the inflammatory response family genes. Eight genes discriminated perfectly between groups A and B: seven up-regulated genes (

PAI1, THBS1, IL8, PTGS2, CXCR4, JUN

, and

FOS

), and one down-regulated gene (

IHH

). In chronic hepatitis C liver samples, a lower or higher expression of a

IL8

was found depending on whether the controls were obtained percutaneously or surgically.

Conclusion:

Our study demonstrates that histologically normal liver tissue obtained in two different ways (percutaneous or surgical) has different gene expression patterns emphasizing the importance of an adequate selection of histologically normal controls to prevent discordant results in gene expression studies. (Hepatology 2008.)
Mortality at 120 days after prostatic biopsy: A population‐based study of 22,175 men
Authors: Gallina Andrea , Suardi Nazareno , Montorsi Francesco , Capitanio Umberto , Jeldres Claudio , Saad Fred , Graefen Markus , Shariat Shahrokh F. , Widmer Hugues , Arjane Philippe , Péloquin François , Perrotte Paul , Karakiewicz Pierre I. 
Published: May 2008

AbstractTrans‐rectal ultrasound guided biopsy of the prostate represents the diagnostic standard for prostate cancer, but its mortality rate has never been examined. We performed a population‐based study of 120‐day mortality after prostate biopsy in 22,175 patients, who underwent prostate biopsy between 1989 and 2000. The control group consisted of 1,778 men aged 65–85 years (median 69.5), who did not undergo a biopsy. Univariable and multivariable logistic regression analyses were performed in 11,087 of 22,175 (50%) men subjected to prostate biopsy, to identify predictors of 120‐day mortality. Variables were age at biopsy, baseline Charlson comorbidity index and cumulative number of biopsy procedures. We externally validated the model's predictors in the remaining 50% of men. Overall 120‐day mortality after biopsy was 1.3% versus 0.3% (p < 0.001) in the control group. Of men aged ≤60 years, 0.2% died within 120 days versus 2.5% aged 76–80. Zero Charlson comorbidity score yielded 0.7% mortality versus 2.2%, if 3–4. First ever biopsy procedures carried a higher mortality risk than subsequent procedures (1.4 vs. 0.8 vs. 0.6%). In the multivariable model, first ever biopsy, increasing age and comorbidity predicted higher mortality. Overall, the model's variables were 79% accurate in predicting the probability of 120‐day mortality after biopsy. In conclusion, our data suggest that prostate biopsy might predispose to higher mortality rate. The certainty of this association remains to be proven. © 2008 Wiley‐Liss, Inc.
Uncertain pathogenicity of MSH2 variants N127S and G322D challenges their classification
Authors: Ollila Saara , Bebek Denis Dermadi , Greenblatt Marc , Nyström Minna 
Published: May 2008

AbstractHereditary non‐polyposis colorectal cancer (HNPCC) is associated with germline mutations in mismatch repair (MMR) genes. Inherited missense mutations, however, complicate the diagnostics because they do not always cause unambiguous predisposition to cancer. This leads to variable and contradictory interpretations of their pathogenicity. Here, we establish evidence for the functionality of the 2 frequently reported variations, MSH2 N127S and G322D, which have been described both as pathogenic and non‐pathogenic in literature and databases. We report the results of 3 different functional analyses characterizing the biochemical properties of these protein variants in vitro. We applied an immunoprecipitation assay to assess the MSH2–MSH6 interaction, a bandshift assay to study mismatch recognition and binding, and a MMR assay for repair efficiency. None of the experiments provided evidence on reduced functionality of these proteins as compared to wild‐type MSH2. Our data demonstrate that MSH2 N127S and G322D per se are not sufficient to trigger MMR deficiency. This together with variable clinical phenotypes in the mutation carriers suggest no or only low cancer risk in vivo. © 2008 Wiley‐Liss, Inc.
Hirudin versus heparin for use in whole blood in vitro biocompatibility models
Authors: Bexborn Fredrik , Engberg Anna E. , Sandholm Kerstin , Mollnes Tom Eirik , Hong Jaan , Nilsson Ekdahl Kristina 
Published: May 2008

AbstractHeparin has traditionally been a widely used anticoagulant in blood research, but has been shown to be inappropriate for work with the complement system because of its complement‐interacting properties. In this work, we have compared the effects of heparin with those of the specific thrombin inhibitor hirudin on complement and blood cells in vitro. Whole blood collected in the presence of hirudin (50 μg/mL) or heparin (1 IU/mL) was incubated in the slide chamber model. The plasma was analyzed for complement activation markers C3a and sC5b‐9, and the polyvinylchloride test slides were stained for adhering cells. The integrity of the complement system was tested by incubating serum and hirudin‐treated plasma in the presence of various activating agents. In contrast to heparin, the addition of hirudin generally preserved the complement reactivity, and complement activation in hirudin plasma closely resembled that in normal serum. Importantly, immunochemical staining of surface‐bound cells demonstrated the inducible expression of tissue factor on bound monocytes from hirudin‐treated blood, an effect that was completely abolished in heparin‐treated blood. Our results indicate that hirudin as an anticoagulant produces more physiological conditions than heparin, making hirudin well‐suited for in vitro studies, especially those addressing the regulation of cellular processes. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Chitosan‐based rechargeable long‐term antimicrobial and biofilm‐controlling systems
Authors: Cao Zhengbing , Sun Yuyu 
Published: May 2008

AbstractChitosan, a natural cationic polymer, strongly binds anionic antibiotics (e.g., rifampin) through the formation of ionic complexes. The new system shows sustained rifampin release, leading to potent antimicrobial and biofilm‐controlling functions against gram‐positive bacteria including Staphylococcus epidermidis and Staphylococcus aureus, which are responsible for a wide range of medical device‐related infections, for longer than 30 days. Moreover, the released drugs can be recharged to further extend antimicrobial durations. Drug release mechanisms and potential applications of the new system are also discussed. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Micro‐Raman spectroscopy (MRS) and surface‐enhanced Raman scattering (SERS) on organic colourants in archaeological pigments
Authors: Van Elslande Elsa , Lecomte Sophie , Le Hô Anne‐Solenn 
Published: May 2008

AbstractDirect identification of organic colourants in heterogeneous matrices of cultural heritage objects with very little or no sampling remains a challenging analytical task.A Raman procedure was investigated for the direct identification of archaeological organic‐coloured pigments found in works of art, without solvent extraction. Conventional micro‐Raman spectroscopy (MRS) using different excitations and surface‐enhanced Raman scattering (SERS) were tested on microscopic samples of paints and cosmetics containing dyes from different sources (animal or vegetal). A tiny lump of purple pigment discovered during excavations in the ancient Minoan city of Akrotiri, on the Santorini Island in Greece (1650 B.C.) and Greco–Roman pink cosmetics were studied. In some cases the results were compared with a range of lake pigments made in the laboratory following historical recipes. Copyright © 2008 John Wiley & Sons, Ltd.
Accelerator mass spectrometry
Authors: Hellborg Ragnar , Skog Göran 
Published: May 2008

AbstractIn this overview the technique of accelerator mass spectrometry (AMS) and its use are described. AMS is a highly sensitive method of counting atoms. It is used to detect very low concentrations of natural isotopic abundances (typically in the range between 10−12 and 10−16) of both radionuclides and stable nuclides. The main advantages of AMS compared to conventional radiometric methods are the use of smaller samples (mg and even sub‐mg size) and shorter measuring times (less than 1 hr). The equipment used for AMS is almost exclusively based on the electrostatic tandem accelerator, although some of the newest systems are based on a slightly different principle. Dedicated accelerators as well as older “nuclear physics machines” can be found in the 80 or so AMS laboratories in existence today. The most widely used isotope studied with AMS is 14C. Besides radiocarbon dating this isotope is used in climate studies, biomedicine applications and many other fields. More than 100,000 14C samples are measured per year. Other isotopes studied include 10Be, 26Al, 36Cl, 41Ca, 59Ni, 129I, U, and Pu. Although these measurements are important, the number of samples of these other isotopes measured each year is estimated to be less than 10% of the number of 14C samples. © 2008 Wiley Periodicals, Inc., Mass Spec Rev 27: 398–427, 2008
Seasonality and diurnal pattern of very low clouds in a deeply incised valley of the eastern tropical Andes (South Ecuador) as observed by a cost‐effective WebCam system
Authors: Bendix Jörg , Rollenbeck Rütger , Göttlicher Dietrich , Nauß Thomas , Fabian Peter 
Published: May 2008

AbstractTo date, the annual and diurnal pattern of low clouds touching the ground in tropical mountains is widely unknown. This holds true for the valley of the Rio San Francisco in southern Ecuador, and is mainly due to a lack of routine cloud observations, which is symptomatic for remote areas in tropical high mountains. A method to use a simple and cost‐effective WebCam system for a quantitative analysis of cloud frequency as a proxy for the occurrence of low‐cloud bases touching the ground is introduced. An interactive classification tool is developed, which is applied to a comprehensive dataset of 32 452 images (during the years 2002–2004) archived at 5 min intervals. The results point to a rapid increase of cloud frequency at altitudes > 2600 m asl both during the day and the year, mainly caused by advective clouds veiling the crests of the Cordillera del Consuelo. Even if the formation of radiation fog directly at the valley bottom is nearly negligible with regard to the whole dataset, scatterometer measurements suggest that valley fog formation on the slopes is a regular process during the night, causing a clear drop in the cloud base around sunrise. The interaction of low‐radiative and high‐advective clouds is supposed to be the driving factor for a rainfall maximum at the valley bottom around sunrise. Higher values of cloud frequency still exist at the crest level around noon: these originate from well‐developed upslope‐breeze systems. Copyright © 2008 Royal Meteorological Society