bluuebunny/crossref_metadata_2025 huggingface dataset:
Decapod crustaceans of soft-sediments on the Aegean Sea coast of Turkey (the eastern Aegean Sea)
Authors: Ateş A. , Katağan Tuncer
Published: April 2008

58 species of decapod crustacean were identified (1 Dendobranchiata, 14 Caridea, 5 Thalassinidea, 14 Anomura, 24 Brachyura) on soft substrates of the Aegean Sea coast of Turkey. Samples were collected from 60 sampling sites along the Turkish Aegean shore (eastern Aegean Sea) between July 2000 and September 2000 with dredge and a van Veen grab at bottom depths of 7 to 150 m. Different species dominated in each ecological zone with the anomuran squat lobster, Galathea intermedia Lilljeborg, 1851, being the most dominant species across the whole sampling area, comprising 11.71% of the individuals collected. This report represents the first published investigations into soft-sediment decapod communities in the coastal waters of the Turkish Aegean Sea.
Diversity and vertical distribution of planktonic ciliates in a stratified mesotrophic lake: relationship to environmental conditions
Authors: Mieczan Tomasz
Published: April 2008

The density and biomass of planktonic ciliates significantly differed between sample sites in a deep, mesotrophic lake, with the lowest numbers in the hypolimnion and the highest in the epilimnion. The community composition varied greatly with depth. Oligotrichs dominated in the epilimnion, where prostomatids and peritrichs were also important components of the community. The density of oligotrichs and peritrichs decreased in the metalimnion, and they were absent from the hypolimnion. In the deep metalimnion the most abundant groups were prostomatids, haptorids and scuticociliates. In the hypolimnion, the ciliate community was dominated by scuticociliates and heterotrichs. In the epilimnion and metalimnion a significant positive correlation was observed between ciliate numbers, chlorophyll a and heterotrophic flagellate density. In all three zones the number of ciliates was most strongly correlated with water temperature, concentrations of total organic carbon (TOC), total phosphorus (Ptot) and bacterial density, whilst in the hypolimnion there was a significant correlation between ciliate numbers and the dissolved oxygen concentration.
Degree of polarization and quantum-mechanical purity
Authors: Moya-Cessa H. , Moya-Cessa J.R. , Landgrave J. E. A. , Martínez-Niconoff G. , Pérez-Leija A. , Friberg A. T.
Published: April 2008

The purity parameter is used in quantum mechanics to discriminate pure states from mixed states. We employ this concept to define a degree of polarization for general, three-dimensional, classical random electric fields. Our approach leads to a result that is identical with a recent definition obtained by a decomposition of the polarization matrix in terms of the Gell-Mann matrices. We also give an expression for this degree of polarization based on the constituent two-dimensional subsystems.
How Large Are Teacher Effects?
Authors: Nye Barbara , Konstantopoulos Spyros , Hedges Larry V.
Published: April 2008

It is widely accepted that teachers differ in their effectiveness, yet the empirical evidence regarding teacher effectiveness is weak. The existing evidence is mainly drawn from econometric studies that use covariates to attempt to control for selection effects that might bias results. We use data from a four-year experiment in which teachers and students were randomly assigned to classes to estimate teacher effects on student achievement. Teacher effects are estimated as between-teacher (but within-school) variance components of achievement status and residualized achievement gains. Our estimates of teacher effects on achievement gains are similar in magnitude to those of previous econometric studies, but we find larger effects on mathematics achievement than on reading achievement. The estimated relation of teacher experience with student achievement gains is substantial, but is statistically significant only for 2nd-grade reading and 3rd-grade mathematics achievement. We also find much larger teacher effect variance in low socioeconomic status (SES) schools than in high SES schools.
Quorum sensing signal disrupts viral infection dynamics in the coccolithophore Emiliania huxleyi
Authors: Harvey EL , Yang H , Castiblanco E , Coolahan M , Dallmeyer-Drennen G , Fukuda N , Greene E , Gonsalves M , Smith S , Whalen KE
Published: April 2008

Viruses that infect phytoplankton are abundant in all regions of the global ocean. Despite their ubiquity, little is understood regarding how biotic interactions can alter virus infection success as well as the fate of phytoplankton hosts. In previous work, the bacterially derived compound 2-heptyl-4-quinolone (HHQ) has been shown to protect the cosmopolitan coccolithophore Emiliania huxleyi from virus-induced mortality. The present study explores the potential mechanisms through which protection is conferred. Using a suite of transmission electron microscopy and physiological diagnostic staining techniques, we show that when E. huxleyi is exposed to HHQ, viruses can gain entry into cells but viral replication and release is inhibited. These findings are supported by a smaller burst size, as well as lower infectious and total virus production when the host is treated with nanomolar concentrations of HHQ. Additionally, diagnostic staining results indicate that programmed cell death markers commonly associated with viral infection are not activated when infected E. huxleyi are exposed to HHQ. Together, these results suggest that the ability of HHQ to inhibit infectious viral production protects the alga not from getting infected, but from cell lysis. This work identifies a new mechanistic role of bacterial quorum sensing molecules in mediating viral infections in marine microbial systems.
Nephrocalcinosis and disordered calcium metabolism in two children with SHORT syndrome
Authors: Reardon William , Temple I. Karen
Published: April 2008

Reports of SHORT syndrome have, to date, focused on the clinical features which lie at the core of the diagnosis but there has been little by way of report of long‐term outcome, either in terms of medical complications or of intellectual development. We now report two children in whom nephrocalcinosis has developed and a third, adult, with similar findings. It may be that clinicians should be looking among cases of unexplained hypercalcaemia for an alternative phenotypic presentation of this short stature syndrome. © 2008 Wiley‐Liss, Inc.
Spatiotemporal Expression of SSeCKS in Injured Rat Sciatic Nerve
Authors: Chen Li , Qin Jing , Cheng Chun , Niu Shuqiong , Liu Yonghua , Shi Shuxian , Liu Hai'ou , Shen Aiguo
Published: April 2008

SSeCKS (src suppressed C kinase substrate) functions in the control of cell signaling and cytoskeletal arrangement. It is expressed in brain and spinal cord, but little is known about its expression in peripheral nerves. In this study, in rats, real‐time polymerase chain reaction and Western blot analysis showed that expression of SSeCKS in crushed sciatic nerve reached its highest level 6 hr after crushing, whereas in a transection model, SSeCKS peaked at 2 days in the proximal stump and 12 hr in the distal stump. Immunohistochemical analysis demonstrated up‐regulation of SSeCKS protein surrounding the crush site and in the two stumps of the transected nerve. In addition, SSeCKS colocalized with growth‐associated protein 43 and with S100, which also changed with time after injury. These findings support the idea that SSeCKS participates in the adaptive response to peripheral nerve injury and may be associated with regeneration. Anat Rec, 291:527–537, 2008. © 2008 Wiley‐Liss, Inc.
A software tool: Type‐2 fuzzy logic toolbox
Authors: Ozek Muzeyyen Bulut , Akpolat Zuhtu Hakan
Published: April 2008

The concept of type‐2 fuzzy set was initially proposed as an extension of classical (type‐1) fuzzy sets. Type‐2 fuzzy sets are very useful in circumstances where it is difficult to determine an exact membership function for a fuzzy set; hence they are very effective for dealing with uncertainties. However, type‐2 fuzzy sets are more difficult to use and understand than type‐1 fuzzy sets. Even in the face of these difficulties, type‐2 fuzzy logic has found applications in many fields. In this article, a new Type‐2 Fuzzy Logic Toolbox written in MATLAB programming language is introduced. The main aim is to help the user to understand and implement type‐2 fuzzy logic systems easily. Type‐2 Fuzzy Logic Controller Block is also prepared for use in SIMULINK. Since general type‐2 fuzzy logic systems are very complicated, they are not preferred in applications. Thus, only interval type‐2 fuzzy logic systems are considered in the proposed Type‐2 Fuzzy Logic Toolbox. Since MATLAB Fuzzy Logic Toolbox users are familiar with its windows, all the menus of the developed software are prepared in the same format of the MATLAB Fuzzy Logic Toolbox. © 2008 Wiley Periodicals, Inc. Comput Appl Eng Educ 16: 137–146, 2008; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae20138
Solution of weighted finite difference techniques with the advection–diffusion equation using spreadsheets
Authors: Karahan Halil
Published: April 2008

This study proposes one‐dimensional advection–diffusion equation (ADE) with finite differences method (FDM) using spreadsheet simulation (ADESS). By changing only the values of weighted parameter with ADESS model, solutions are obtained for the FTSC, Upwind and Lax–Wendroff schemes. Two examples which, have the numerical and analytical solutions in literature, are solved in order to test the proposed model. Both examples are solved for three schemes. It has been determined that the Lax–Wendroff scheme is in good agreement with the analytical solution; however the results of FTSC is lower than the analytical solution and the Upwind scheme is higher than the analytical solution. Moreover, it has been obtained that the model accuracy is higher than that of the other models in literature, when the results of the ADESS model are compared with the numerical solutions. Results showed that by changing the input parameters in the ADESS model, the results of the model may easily be examined graphically. © 2008 Wiley Periodicals, Inc. Comput Appl Eng Educ 16: 147–156, 2008; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae20140
New methodologies in teaching e‐structural mechanics using WWW
Authors: Maiorana Carmelo , Sgarbossa Laura , Salomoni Valentina
Published: April 2008

A recently initiated phase of experimentation and research in the online Distance Learning (DL) is here described. The project has been developed by the Department of Construction and Transportation Engineering of the Faculty of Engineering at the University of Padua along with the well‐established e‐learning experience of the SSIS Veneto (Institute for the Formation of Secondary School's Teachers) of Cà Foscari—University of Venice, in collaboration with the webmaster management of TCN‐EnginSoft of Padua. The work deals with teaching methodologies supported by the net, computer communication and information technologies, finalized to give both widespread access to useful resources and to create a more flexible exchange due to net communication. The experimentation of using web‐based technologies to support traditional teaching for working students is described; in fact, Internet‐based innovations offer opportunities for a curriculum improvement to those categories of students who could be considered at a disadvantage, like worker students or students with ear or motion deafness. © 2008 Wiley Periodicals, Inc. Comput Appl Eng Educ 16: 189–210, 2008; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae20167
New Strategies for the Synthesis of Pyrimidine Derivatives
Authors: Hill Matthew D. , Movassaghi Mohammad
Published: April 2008

Recent advances in pyrimidine synthesis are described. Modification of conventional strategies involving N‐C‐N fragment condensation with 1,3‐dicarbonyl derivatives remains a common theme in current literature. Other methods, including N–C fragment condensation strategies, provide reactive intermediates capable of intramolecular cyclization and formation of pyrimidine derivatives. These recently developed methodologies offer a valuable addendum to azaheterocycle synthesis.
Investigation of Biosorption Behavior of Methylene Blue on Pleurotus ostreatus (Jacq.) P. Kumm.
Authors: İslek Cemil , Sinağ Ali , Akata Ilgaz
Published: April 2008

The effect of varying parameters such as dye concentration, adsorbent dose, pH and temperature on the adsorption capacity of Pleurotus ostreatus is investigated. The commonly available white rot fungus Pleurotus ostreatus is investigated as a viable biomaterial for the biological treatment of synthetic basic methylene blue effluents. The results obtained from the batch experiments reveal the ability of the fungus to remove methylene blue. The performance is dependent on the dye concentration, pH, and fungal biomass. The equilibrium and kinetics of adsorption are investigated and the Langmuir equation is used to fit the equilibrium isotherm. The adsorption isotherm of methylene blue follows only the Langmuir model with a correlation coefficient of ca. 0.96–0.99. The maximum adsorption capacity is ca. 70 mg of dye per g of dry fungus at pH 11, 70 mg L–1 dye, and 0.1 g L–1 fungus concentration, respectively. This study demonstrates that the fungus could be used as an effective biosorbent for the treatment of dye‐containing wastewater streams.
Nucleus paragigantocellularis afferents in male and female rats: Organization, gonadal steroid receptor expression, and activation during sexual behavior
Authors: Normandin Joseph J. , Murphy Anne Z.
Published: April 2008

The supraspinal regulation of genital reflexes is poorly understood. The brainstem nucleus paragigantocellularis (nPGi) of rats is a well‐established source of tonic inhibition of genital reflexes. However, the organization, gonadal steroid receptor expression, and activity of nPGi afferents during sex have not been fully characterized in male and female rats. To delineate the anatomical and physiological organization of nPGi afferents, the retrograde tracer Fluoro‐Gold (FG) was injected into the nPGi of sexually experienced male and female rats. Animals engaged in sexual behavior 1 hour before sacrifice. Cells containing FG, estrogen receptor‐α (ERα), androgen receptor (AR), and the immediate‐early gene product Fos were identified immunocytochemically. Retrograde labeling from the nPGi was prominent in the bed nucleus of the stria terminalis, paraventricular nucleus (PVN), posterior hypothalamus, precommissural nucleus, deep mesencephalic nucleus, and periaqueductal gray (PAG) of both sexes. Sex differences were observed in the caudal medial preoptic area (MPO), with significantly more FG+ cells observed in males, and in the PAG and inferior colliculus, where significantly more FG+ cells were observed in females. The majority of regions that contained FG+ cells also contained ERα or AR, indicating sensitivity to gonadal steroids. The proportions of FG+ cells that co‐localized with sex‐induced Fos was high in the PVN of both sexes and high in the MPO of males but low in the PAG of both sexes despite the large number of PAG‐nPGi output neurons and Fos+ cells in both sexes. The characterization of these afferents will lead to a further understanding of the neural regulation of genital reflexes. J. Comp. Neurol. 508:771–794, 2008. © 2008 Wiley‐Liss, Inc.
Domperidone interferes with conditioned disgust reactions but not taste avoidance evoked by a LiCl‐paired taste in infant rats
Authors: Pautassi Ricardo Marcos , Arias Carlos , Molina Juan Carlos , Spear Norman
Published: April 2008

Rats exhibit taste avoidance and conditioned disgust reactions when stimulated with a tastant paired with lithium chloride (LiCl). Lithium‐mediated activation of chemoreceptor nuclei at the brainstem appears to determine the acquisition of conditioned taste aversion (CTA) in adult rodents. Domperidone (DOM), an anti‐emetic drug that does not cross the blood–brain barrier, was employed to analyze mechanisms underlying LiCl‐mediated CTA in infant rats. On postnatal day 13 animals were given DOM followed by a pairing between intraoral saccharin and LiCl. Saccharin consumption at testing was lower in lithium‐treated pups than in controls. DOM did not interfere with this LiCl‐mediated taste avoidance but significantly decreased LiCl‐mediated disgust reactions (head‐shaking and wall climbing). Activation of the emetic system of the brainstem does not seem necessary for the acquisition of LiCl‐mediated conditioned taste avoidance. Yet, these centers seem to be involved in the palatability shift resulting from taste‐LiCl pairings. These results indicate an early dissociation between conditioned disgust reactions and conditioned taste avoidance. © 2008 Wiley Periodicals, Inc. Dev Psychobiol 50: 343–352, 2008.
Effects of early weaning on anxiety and prefrontal cortical and hippocampal myelination in male and female wistar rats
Authors: Kodama Yuka , Kikusui Takefumi , Takeuchi Yukari , Mori Yuji
Published: April 2008

We investigated developmental changes in myelin formation in the prefrontal cortex and the hippocampus, and behavioral effects of early weaning in Wistar rats. Early‐weaned rats showed decreased numbers of open‐arm entries in an elevated plus‐maze in both sexes at 4 weeks old; this effect persisted in males, but ceased in females after this age. Expression of myelin basic protein (MBP) showed both age‐dependent increases and sex differences; 4‐week‐old males exhibited higher MBP levels in the hippocampus, whereas 7‐week‐old males showed lower MBP levels in the prefrontal cortex compared to females of the same age. There was a tendency for group differences from weaning for the 21.5‐kDa isoform in the prefrontal cortex. Although these results suggest that male rats are more vulnerable than females to early‐weaning effects on anxiety‐related behaviors, further detailed analysis is needed to clarify the functional relationship between myelination and anxiety‐related behaviors. © 2008 Wiley Periodicals, Inc. Dev Psychobiol 50: 332–342, 2008.
Rats selectively bred for low levels of 50 kHz ultrasonic vocalizations exhibit alterations in early social motivation
Authors: Harmon K.M. , Cromwell H.C. , Burgdorf J. , Moskal J.R. , Brudzynski S.M. , Kroes R.A. , Panksepp J.
Published: April 2008

In rats, the rates of 50 kHz ultrasonic vocalizations (USVs) can be used as a selective breeding phenotype and variations in this phenotype can be an indicator of affective states. The 50 kHz USV is elicited by rewarding stimuli (e.g., food, sexual behavior) and therefore can express a positive affective state. Conversely, the 22 kHz USV is elicited by aversive stimuli (e.g., presence of a predator, social defeat) indicating a negative affective state. In the present study, we tested the effect of selectively breeding for 50 kHz USVs on a variety of maternal social/emotional behaviors in young rat pups (PND 10‐12). These measures consisted of an assessment of isolation calls and conditioned odor preference paradigm. Results indicate that animals selected for low levels of 50 kHz USVs show the greatest alterations in social behaviors compared to the control animals. The low line animals had an increase in isolation calls tested during place preference conditioning and a decrease in 50 kHz ultrasonic calls in all conditions. These same low line animals failed to show a typical preference for a maternally‐associated odor during the place preference test. The different social behaviors of the high line animals did not consistently vary from those of the control group. These results have important implications for the study of genetic and epigenetic mechanisms underlying emotional states, and possibly contribute to the research underlying the emotional changes in developmental disorders such as autistic spectrum disorder by providing a novel animal model that displays communication deficits that are interdependent with significant social behavioral impairments. © 2008 Wiley Periodicals, Inc. Dev Psychobiol 50: 322–331, 2008.
Could adults be used to improve social skills of young horses, Equus caballus?
Authors: Bourjade Marie , Moulinot Maïc , Henry Séverine , Richard‐Yris Marie‐Annick , Hausberger Martine
Published: April 2008

We investigated the effects of the introduction of foreign adults on the behavior of young horses. First, we observed the behavior of 1‐ and 2‐year‐old domestic horses housed in same‐age and same‐sex groups (a standard housing system, but different from a natural situation). Then, two same‐sex adults were introduced into each experimental group. Observations made before, during and after an introduction indicated that young horses reared in homogeneous groups of young had different behaviors compared to other domestic horses reared under more socially natural conditions. After the introduction of adults, young horses expressed new behaviors, preferential social associations emerged, positive social behavior increased and agonistic interactions decreased. These results have important implications both for understanding the influence that adults may have on the behavior of young horses, and in terms of husbandry, indicating the importance of keeping young horses with adults, although further studies are still necessary. © 2008 Wiley Periodicals, Inc. Dev Psychobiol 50: 408–417, 2008.
FGF signaling segregates biliary cell‐lineage from chick hepatoblasts cooperatively with BMP4 and ECM components in vitro
Authors: Yanai Masaaki , Tatsumi Norifumi , Hasunuma Noboru , Katsu Kenjiro , Endo Fumio , Yokouchi Yuji
Published: April 2008

Intrahepatic bile ducts (IHBDs) are indispensable for transporting bile secreted from hepatocytes to the hepatic duct. The biliary epithelial cells (BECs) of the IHBD arise from bipotent hepatoblasts around the portal vein, suggesting the portal mesenchyme is essential for their development. However, except for Notch or Activin/TGF‐β signaling molecules, it is not known which molecules regulate IHBD development. Here, we found that FGF receptors and BMP4 are specifically expressed in the developing IHBD and the hepatic mesenchyme, respectively. Using a mesenchyme‐free culture of liver bud, we showed that bFGF and FGF7 induce the hepatoblasts to differentiate into BECs, and that BMP4 enhances bFGF‐induced BEC differentiation. The extracellular matrix (ECM) components in the hepatic mesenchyme induced BEC differentiation. Forced expression of a constitutively active form of the FGF receptor partially induced BEC differentiation markers in vivo. These data strongly suggest that bFGF and FGF7 promote BEC differentiation cooperatively with BMP4 and ECMs in vivo. Developmental Dynamics 237:1268‐1283, 2008. © 2008 Wiley‐Liss, Inc.
Assembly of primary cilia
Authors: Pedersen Lotte B. , Veland Iben R. , Schrøder Jacob M. , Christensen Søren T.
Published: April 2008

Primary cilia are microtubule‐based, hair‐like sensory organelles present on the surface of most growth‐arrested cells in our body. Recent research has demonstrated a crucial role for primary cilia in regulating vertebrate developmental pathways and tissue homeostasis, and defects in genes involved in primary cilia assembly or function have been associated with a panoply of disorders and diseases, including polycystic kidney disease, left‐right asymmetry defects, hydrocephalus, and Bardet Biedl Syndrome. Here we provide an up‐to‐date review focused on the molecular mechanisms involved in the assembly of primary cilia in vertebrate cells. We present an overview of the early stages of the cilia assembly process, as well as a description of the intraflagellar transport (IFT) system. IFT is a highly conserved process required for assembly of almost all eukaryotic cilia and flagella, and much of our current knowledge about IFT is based on studies performed in Chlamydomonas and Caenorhabditis elegans. Therefore, our review of the IFT literature includes studies performed in these two model organisms. The role of several non‐IFT proteins (e.g., centrosomal proteins) in the ciliary assembly process is also discussed. Developmental Dynamics 237:1993–2006, 2008. © 2008 Wiley‐Liss, Inc.
Nodal and lefty signaling regulates the growth of pancreatic cells
Authors: Zhang You‐Qing , Sterling Lori , Stotland Aleksandr , Hua Hong , Kritzik Marcie , Sarvetnick Nora
Published: April 2008

Nodal and its antagonist, Lefty, are important mediators specifying the laterality of the organs during embryogenesis. Nodal signals through activin receptors in the presence of its co‐receptor, Cripto. In the present study, we investigated the possible roles of Nodal and Lefty signaling during islet development and regeneration. We found that both Nodal and Lefty are expressed in the pancreas during embryogenesis and islet regeneration. In vitro studies demonstrated that Nodal inhibits, whereas Lefty enhances, the proliferation of a pancreatic cell line. In addition, we showed that Lefty‐1 activates MAPK and Akt phosphorylation in these cells. In vivo blockade of endogenous Lefty using neutralizing Lefty‐1 monoclonal antibody results in a significantly decreased proliferation of duct epithelial cells during islet regeneration. This is the first study to decipher the expression and function of Nodal and Lefty in pancreatic growth. Importantly, our results highlight a novel function of Nodal‐Lefty signaling in the regulation of expansion of pancreatic cells. Developmental Dynamics 237:1255‐1267, 2008. © 2008 Wiley‐Liss, Inc.
Bis‐ and Tris(tetraazamacrocyclic) Copper Complexes with Disulfide Linkers
Authors: Galińska Monika , Korybut‐Daszkiewicz Bohdan , Wawrzyniak Urszula E. , Bilewicz Renata , Śledź Pawel , Kamiński Radosław , Dominiak Paulina , Woźniak Krzysztof
Published: April 2008

Di‐ and trinuclear title complexes, 2Cu and 3Cu, containing, respectively, two and three macrocyclic fragments bound by aliphatic linkers with the ‐S–S‐ moieties have been synthesized by using cystamine dihydrochloride in the presence of triethylamine. The structure of the 2Cu complex in the solid state was confirmed by X‐ray analysis. Two macrocyclic rings of 2Cu form a rectangular cavity of size 17.18 Å [S19···S19 (1 – x, –y, –z)] × 3.62 Å. The shorter dimension of the cavity is the shortest observed in bis(macrocycle)s studied by us. The bis(macrocyclic) molecules in the crystal lattice are surrounded by PF6– ions and water molecules. Redox properties of the new compounds were determined by applying various voltammetric techniques. The macrocyclic architectures remained stable in nonaqueous solutions. For the bis‐ and tris(macrocyclic) compounds, the exchange of one electron takes place almost independently at each of the copper centers. The complexes were self‐ assembled at the gold surface to produce stable monolayer‐modified electrodes. The immobilization of these highly charged cations on the electrode required the application of appropriate negative potentials during the self‐assembly process.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
A Study on the Coordinative Versatility of the Zwitterionic S,N,S Ligand EtNHC(S)­Ph2P=NPPh2C(S)NEt in Its Anionic, Neutral and Cationic Forms – Determination of Absolute pKa Values in CH2Cl2 of RhI Complexes
Authors: Delferro Massimiliano , Cauzzi Daniele , Pattacini Roberto , Tegoni Matteo , Graiff Claudia , Tiripicchio Antonio
Published: April 2008

The coordination properties of EtNHC(S)Ph2P=NPPh2C(S)NEt (HEtSNS) towards RhI species derived from [Rh(CO)2Cl]2 and [Rh(cod)Cl]2 (cod = 1,5‐cyclooctadiene) were studied. This ligand is an amphoteric zwitterion, which forms the H2EtSNS+ cation upon protonation and the EtSNS– dianion–cation upon deprotonation. All three forms coordinate to metal centers. Their geometrical versatility allows many coordination fashions: S‐monodentate; S,S‐bidentate (with a bite angle spanning from 90 to 180°); S,N,S‐tridentate; N,N,N‐tridentate; and S,S‐bridging, as determined by X‐ray diffraction methods. The [Rh(CO)EtSNS] complex is a biprotic base; its conjugated acids are [Rh(CO)HEtSNS]+ and [Rh(CO)H2EtSNS]2+, and their pKa values were determined in dichloromethane solutions. In this triad of compounds, which are geometrically similar, the RhI metal center features variable charge density as confirmed by the νCO infrared absorption frequency.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
A Ferromagnetically Coupled Diiron(III) Complex with a m‐Phenylenediamine‐Based Ligand
Authors: Biswas Biplab , Salunke‐Gawali Sunita , Weyhermüller Thomas , Bachler Vinzenz , Bill Eckhard , Chaudhuri Phalguni
Published: April 2008

The Schiff base ligand H2L, N,N′‐bis(3,5‐di‐tert‐butylsalicylidene)‐1,3‐diaminobenzene yields a diferric complex, [L2FeIII2(NO3)2] (1), in which the d5 high‐spin iron(III) centers are ferromagnetically coupled through the spin polarization mechanism. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Development of a new procedure for lipid extraction from Hevea brasiliensis natural rubber
Authors: Liengprayoon Siriluck , Bonfils Frederic , Sainte‐Beuve Jerome , Sriroth Klanarong , Dubreucq Eric , Vaysse Laurent
Published: April 2008

Non‐isoprene components and especially lipids have been reported to be involved in some key properties of natural rubber. Unfortunately, these results are hardly comparable due to different extraction methods. This work aimed to optimize lipid extraction from natural rubber either in the liquid state (latex) or in the dry state (unsmoked sheets). Extraction of unsmoked sheets from the RRIM 600 clone was carried out with different combinations of organic solvents (chloroform/methanol and hexane/isopropanol mixes). Chloroform/methanol (2 : 1 vol/vol) was found to be the most suitable for lipid extraction from unsmoked sheet rubber. The lipid extraction yield was improved by increasing the exchange surfaces by grinding rubber under liquid nitrogen and extracting the ground rubber for 6 h at room temperature, leading to 1.82% lipid extraction yield (versus dry rubber). Concerning latex extraction, the problem of lipid entrapment in the coagulum from immediate coagulation of latex in the solvent was solved by preliminary two times dilution of latex, giving a 3.24% extract (versus dry rubber) containing a minimum quantity of contaminating polyisoprene. Concerning the nature of lipids, dilution increased mainly neutral lipid extraction, which may suggest that neutral lipids were those entrapped by coagulation.
The Introduction of Asymmetry into Alkyl‐Decorated Fréchet‐Type Dendrons
Authors: Constable Edwin C. , Graber Stefan , Hermann B. A. , Housecroft Catherine E. , Malarek Michael S. , Scherer Lukas J.
Published: April 2008

A strategy for the introduction of asymmetry into Fréchet‐type dendrons bearing n‐alkyl chains is described. Starting from a methyl 3,5‐dihydroxybenzoate core, 3,5‐bis(octyloxyphenyl)methoxy and 3,5‐bis(alkoxyphenyl)methoxy units are introduced in a stepwise manner. The method is illustrated by the syntheses of four representative compounds having mixed n‐octyl/n‐butyl, n‐octyl/n‐hexyl, n‐octyl/n‐heptyl and n‐octyl/n‐dodecyl substituents. The new compounds have been characterized by spectroscopic and mass spectrometric techniques. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Backbone Amide Linker Strategy for the Synthesis of 1,4‐Triazole‐Containing Cyclic Tetra‐ and Pentapeptides
Authors: Springer Jasper , de Cuba Kimberly R. , Calvet‐Vitale Sandrine , Geenevasen Jan A. J. , Hermkens Pedro H. H. , Hiemstra Henk , van Maarseveen Jan H.
Published: April 2008

A backbone amide linker strategy was chosen for the solid‐phase synthesis of triazole‐containing cyclic tetra‐ and pentapeptides. An alkyne‐substituted linker derived from 4‐hydroxy‐2‐methoxybenzaldehyde was elongated by using standard “Fmoc‐based” solid phase chemistry and terminated by coupling of an azido acid. In solution, the peptides were cyclized by a CuI‐catalyzed azide‐alkyne cycloaddition reaction. The solid‐supported synthesized linear peptides had to be cleaved prior to cyclization. As an example of cyclic tetrapeptides, a triazole analog of cyclo‐[Pro‐Val‐Pro‐Tyr] (2) was prepared by the solid‐phase/solution‐phase method. For the cyclic pentapeptides, segetalin B (3) was chosen as a model compound to show the applicability of this method.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
A distributed shear and flexural flexibility model with shear–flexure interaction for R/C members subjected to seismic loading
Authors: Mergos P. E. , Kappos A. J.
Published: April 2008

A beam–column‐type finite element for seismic assessment of reinforced concrete (R/C) frame structures is presented. This finite element consists of two interacting, distributed flexibility sub‐elements representing inelastic flexural and shear response. Following this formulation, the proposed model is able to capture spread of flexural yielding, as well as spread of shear cracking, in R/C members. The model accounts for shear strength degradation with inelastic curvature demand, as well as coupling between inelastic flexural and shear deformations after flexural yielding, observed in many experimental studies. An empirical relationship is proposed for evaluating the average shear distortion of R/C columns at the onset of stirrup yielding. The proposed numerical model is validated against experimental results involving R/C columns subjected to cyclic loading. It is shown that the model can predict well the hysteretic response of R/C columns with different failure modes, i.e. flexure‐critical elements, elements failing in shear after flexural yielding, and shear‐critical R/C members. Copyright © 2008 John Wiley & Sons, Ltd.
Gold‐silver and silver‐silver nanoparticle constructs based on DNA hybridization of thiol‐ and amino‐functionalized oligonucleotides
Authors: Steinbrück A. , Csaki A. , Ritter K. , Leich M. , Köhler J. M. , Fritzsche W.
Published: April 2008

Metal nanoparticle constructs of particles of different sizes and materials were prepared, using DNA as connecting element. Therefore, gold and silver nanoparticles were functionalized with complementary DNA sequences that enabled a controlled coupling. The well‐established system based on thiolated DNA was thereby complemented with amino‐functionalized DNA. The realization of specific DNA‐DNA bonds due to hybridization was controlled by the ionic strength. The results demonstrate the potential of the combination of different particle sizes, composition as well as coupling chemistry in order to realize controlled conjugates of nanoparticles. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Where shall we meet? A role for genome organisation and nuclear sub‐compartments in mediating interchromosomal interactions
Authors: Osborne Cameron S. , Eskiw Christopher H.
Published: April 2008

A recent spate of examples of specific interactions between loci on separate chromosomes in mammalian nuclei has illuminated another layer of complexity in gene regulation. As the specifics of the cross‐talk between interacting loci are worked out, it is also important to consider exactly how, when and where loci can ever reliably find each other within such an intricate environment. Answers may lie in how the genome is organised in relation to itself and to specialised nuclear sub‐compartments. Here, we discuss how such specialised nuclear bodies may have the potential to specifically sequester loci and provide a context where interchromosomal communications can occur. J. Cell. Biochem. 104: 1553–1561, 2008. © 2008 Wiley‐Liss, Inc.
Associative versus dissociative binding of CO to 4d transition metal trimers: A density functional study
Authors: Addicoat Matthew A. , Buntine Mark A. , Yates Brian , Metha Gregory F.
Published: April 2008

Density functional calculations were performed to determine equilibrium geometrical structures, transition states and relative energies for M3 clusters (M = Nb, Mo, Tc, Ru, Rh, Pd, Ag) reacting with CO, leading to proposed reaction pathways. For the Nb3, Mo3, and Tc3 clusters, the lowest energy structure correlates to dissociated CO, with the C and O atoms bound on opposite sides of the metal triangle. For all other trimers, the lowest energy structures maintain the CO moiety. In the case of Pd3 and Ag3 the dissociated geometries lie higher in energy than the sum of the separated reactants. In most cases, several multiplicities were found to be similar in energy and for Mo3CO and Pd3CO singlet‐triplet minimum energy crossing points were identified. In the case of Rh3CO, minimum energy crossing points for the doublet, quartet, and sextet reaction pathways were determined and compared. The electron densities of pertinent M3CO species were investigated using Natural Bond Order calculations. It was found that the effect of the metal trimer on the energy of the pure p‐type π* antibonding orbital of carbon monoxide directly correlates with the occurrence of CO dissociation. © 2008 Wiley Periodicals, Inc.J Comput Chem, 2008.
Inflammatory responses of endothelial cells experiencing reduction in flow after conditioning by shear stress
Authors: Matharu Nick M. , McGettrick Helen M. , Salmon Mike , Kissane Steve , Vohra Rajiv K. , Rainger G.Ed. , Nash Gerard B.
Published: April 2008

Exposure of endothelial cells (EC) to shear stress reduces their response to tumour necrosis factor‐α (TNF). We tested how shear‐conditioned EC responded to reduction in flow, either by spontaneously binding leukocytes, or by increasing sensitivity to TNF. Human umbilical vein EC were exposed to shear stress of 2.0 Pa (20 dyn/cm2) for 24 h. Shear was then reduced to stasis (30 sec perfusion each hour to exchange medium) or 0.003 Pa (creeping flow). At chosen times, neutrophils were perfused over the EC at 0.1 Pa (effective reperfusion). EC developed an ability to capture flowing neutrophils that lasted from 1 to 3 h after flow reduction, which was reduced by antibody against P‐selectin or pre‐treatment of EC with an inhibitor of NADPH‐oxidase. Adhesion of neutrophils to TNF‐treated EC was greatly suppressed by shear‐conditioning, remained suppressed immediately after cessation of flow and then took 48 h to approach the level in static cultures. Interestingly, the response to TNF remained suppressed in cultures switched to creeping flow. Gene array analysis confirmed that differently recovered cells had separate phenotypes. Thus, an acute response of EC to reduction in shear may contribute to leukocyte recruitment, along with hypoxia, in ischaemia and reperfusion. Prolonged cessation of flow may increase the sensitivity of EC to inflammatory stimuli, but this effect may be suppressed by residual flow. J. Cell. Physiol. 216: 732–741, 2008, © 2008 Wiley‐Liss, Inc.
Solubilization at high pH results in improved recovery of proteins from inclusion bodies of E. coli
Authors: Singh Surinder M. , Upadhyay Arun K. , Panda Amulya K.
Published: April 2008

BACKGROUND: Solubilization of inclusion bodies using high concentration of chaotropes followed by suboptimal refolding results in lower recovery of bioactive proteins from E. coli. Growing evidence indicates that aggregation of expressed proteins into inclusion bodies is molecular specific in nature and proteins in inclusion bodies have native‐like secondary structure. Protecting these pre‐existing native‐like secondary structures of proteins using mild solubilization conditions is one of the key steps in improved recovery of bioactive protein from inclusion bodies of E. coli.

RESULTS: Inclusion bodies of seven proteins (hGH, oGH, Pyk, PKS, aldolase, enolase and superoxide dismutase) were solubilized at pH 12 in the presence of 2 mol L−1 urea and were subsequently refolded and purified. Enrichment of inclusion bodies after cell lysis, mild solubilization at alkaline pH and pulsatile refolding resulted in lower aggregation of protein during refolding and improved the final recovery of protein from inclusion bodies of E. coli. The efficiency of protein recovery from inclusion bodies was 30–40% for most of the proteins. This was almost two times higher than that achieved when inclusion bodies were solubilized in 8 mol L−1 urea and subsequently refolded. Purified hGH and Pyk were functionally active in respective in vitro assays.

CONCLUSION: Non‐denaturing solubilization of inclusion body proteins at alkaline pH is a viable alternative to the use of high molar concentration chaotropes for efficient recovery of inclusion body proteins. Mild solubilization and pulsatile refolding contribute synergistically to reduce the extent of aggregation during refolding and result in high throughput recovery of bioactive proteins from inclusion bodies of E. coli. Copyright © 2008 Society of Chemical Industry
Nondestructive optical determination of fiber organization in intact myocardial wall
Authors: Smith Rebecca M. , Matiukas Arvydas , Zemlin Christian W. , Pertsov Arkady M.
Published: April 2008

Mapping the myocardial fiber organization is important for assessing the electrical and mechanical properties of normal and diseased hearts. Current methods to determine the fiber organization have several limitations: histological sectioning mechanically distorts the tissue and is labor‐intensive, while diffusion tensor imaging has low spatial resolution and requires expensive MRI scanners. Here, we utilized optical clearing, a fluorescent dye, and confocal microscopy to create three‐dimensional reconstructions of the myocardial fiber organization of guinea pig and mouse hearts. We have optimized the staining and clearing procedure to allow for the nondestructive imaging of whole hearts with a thickness up to 3.5 mm. Myocardial fibers could clearly be identified at all depths in all preparations. We determined the change of fiber orientation across strips of guinea pig left ventricular wall. Our study confirms the qualitative result that there is a steady counterclockwise fiber rotation across the ventricular wall. Quantitatively, we found a total fiber rotation of 105.7 ± 14.9° (mean ± standard error of the mean); this value lies within the range reported by previous studies. These results show that optical clearing, in combination with a fluorescent dye and confocal microscopy, is a practical and accurate method for determining myocardial fiber organization. Microsc. Res. Tech., 2008. © 2008 Wiley‐Liss, Inc.
AFM characterization of rabbit spermatozoa
Authors: Ierardi Vincenzo , Niccolini Alberto , Alderighi Michele , Gazzano Angelo , Martelli Franco , Solaro Roberto
Published: April 2008

Atomic force microscopy (AFM) has been applied for determining the topological and structural features of rabbit spermatozoa. Fresh ejaculated spermatozoa were adsorbed passively onto a silicon slide or by motility from suspension onto a poly(L‐lysine)‐coated glass coverslip and then imaged in air and in buffer saline, respectively. AFM images clearly highlighted many details of spermatozoa head, neck, and tail. Distinct features were observed in the plasmatic membrane of spermatozoa. In particular, head topography easily recognized the acrosome, equatorial segment, equatorial subsegment, and postacrosome regions. Moreover, AFM images revealed the presence of double belt of invaginations around the spermatozoa head, at the boundary between equatorial subsegment and postacrosome regions. All together, the collected AFM images clearly defined a detailed map of spermatozoa morphology while giving some hints on the internal structure. Microsc. Res. Tech., 2008. © 2008 Wiley‐Liss, Inc.
Angiofil®‐mediated visualization of the vascular system by microcomputed tomography: A feasibility study
Authors: Grabherr Silke , Hess Andreas , Karolczak Marek , Thali Michael J. , Friess Sebastian D. , Kalender Willi A. , Dirnhofer Richard , Djonov Valentin
Published: April 2008

Visualization of the vascular systems of organs or of small animals is important for an assessment of basic physiological conditions, especially in studies that involve genetically manipulated mice. For a detailed morphological analysis of the vascular tree, it is necessary to demonstrate the system in its entirety. In this study, we present a new lipophilic contrast agent, Angiofil®, for performing postmortem microangiography by using microcomputed tomography. The new contrast agent was tested in 10 wild‐type mice. Imaging of the vascular system revealed vessels down to the caliber of capillaries, and the digital three‐dimensional data obtained from the scans allowed for virtual cutting, amplification, and scaling without destroying the sample. By use of computer software, parameters such as vessel length and caliber could be quantified and remapped by color coding onto the surface of the vascular system. The liquid Angiofil® is easy to handle and highly radio‐opaque. Because of its lipophilic abilities, it is retained intravascularly, hence it facilitates virtual vessel segmentation, and yields an enduring signal which is advantageous during repetitive investigations, or if samples need to be transported from the site of preparation to the place of actual analysis, respectively. These characteristics make Angiofil® a promising novel contrast agent; when combined with microcomputed tomography, it has the potential to turn into a powerful method for rapid vascular phenotyping. Microsc. Res. Tech., 2008. © 2008 Wiley‐Liss, Inc.
Spatial heterogeneity of soil properties and its mapping with apparent electrical conductivity
Authors: Michael Mertens Franz , Pätzold Stefan , Welp Gerhard
Published: April 2008

The site‐specific cultivation as part of the precision‐agriculture concept is more and more introduced into practical farming. However, soil information is often not available in a spatial resolution intrinsically needed for precision farming or other site‐specific soil use and management purposes. One approach to obtain spatially high‐resolution soil data is the non‐invasive measurement of the apparent electrical conductivity (ECa). In this study, we recorded the ECa on three fields with an EM38 (Geonics, Canada). The ECa data were compared with (1) ground truth data obtained by conventional drilling, (2) traditional soil maps (large scale, ≤1:5,000), (3) the growth and yield of corn. The temporal variability of the ECa due to varying soil moisture and temperature was taken into account by repeated measurements of the same fields and subsequent averaging of the ECa values. Significant correlations (r² = 0.76) were found between the mean weighted clay content (0–1.5 m) and the ECa. Furthermore, in soils with differently textured layers, ECa was used to estimate the thickness of the uppermost loess layer. A comparison of ECa and large‐scale soil maps reveals some pros and cons of ECa measurements. The main advantages of ECa recordings are the high spatial resolution in combination with low efforts. Yet, the ECa signal is no direct measure for a soil type or unit. Depending on the variability of substrates and layering, the ECa pattern can be a precise indicator for the spatial distribution of different soils. A strong conformity of the spatial variability of plant growth (derived from orthophotos and yield maps) and ECa patterns within a field indicates that the ECa signal per se—without conversion to traditional soil parameters—integrates the effects of various soil variables that govern soil fertility. Altogether, ECa surveys can be a powerful tool to facilitate and improve conventional soil mapping.