bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantitative Structure-Activity Relationships of Noncompetitive Antagonists of the NMDA Receptor: A Study of a Series of MK801 Derivative Molecules Using Statistical Methods and Neural Network
Authors: Elhallaoui M. , Elasri M. , Ouazzani F. , Mechaqrane A. , Lakhlifi T.
Published: October 2008

From a series of 50 MK801 derivative molecules, a selected set of 44 compounds was submitted to a principal components analysis (PCA), a multiple regression analysis (MRA), and a neural network (NN). This study shows that the compounds' activity correlates reasonably well with the selected descriptors encoding the chemical structures. The correlation coefficients calculated by MRA and there after by NN, r = 0.986 and r = 0.974 respectively, are fairly good to evaluate a quantitative model, and to predict activity for MK801 derivatives. To test the performance of this model, the activities of the remained set of 6 compounds are deduced from the proposed quantitative model, by NN. This study proved that the predictive power of this model is relevant.
Electrical Conductivity along Phase Diagram of the Critical Mixture Isobutyric Acid – Water with Added (K+, Cl-) Ions
Authors: Cherif Emna , Bouanz Moncef
Published: October 2008

Three systems, isobutyric acid – water (I–W), “(I-W) + 5 10-4 M (KCl)” and “(IW) + 5 10-3 M (KCl)”, have been studied by measuring the electrical conductivity σ (Ω-1cm-1) along the coexistence curve in a single phase, as a function of the variations temperature T and composition X in acid. The coefficient σ is a temperature dependent parameter for ions, increasing as temperature is elevated. Contrary to the visconty, the electrical conductivity does not show any anomaly in the critical region.
Theoretical Calculation of Absolute Radii of Atoms and Ions. Part 2. The Ionic Radii
Authors: Ghosh Dulal  C. , Biswas Raka
Published: October 2008

The theoretical method of determination of absolute atomic size, discussed in Int. J. Mol. Sci. 2002, 3, 87-113, is exploited to calculate absolute radii of the ions whose experimental radii are published by Shanon. The computed radii are found to reproduce the expected periodic variation of size in periods and in groups and nicely reproduce the d-block and f-block contractions in the respective series. It is pointed out that experimental radii of d and f block transition metal ions make erroneous and misleading representation of the size behaviour of the respective series. A detailed comparative study of the crystal radii vis-à-vis the theoretical radii is reported. A rationale of the double hump curve of the experimental radii of 3 d-block transition metal ions is put forward in terms of the crystal field theory and Jahn-Teller distortion. The theoretical radii are exploited to calculate the diamagnetic susceptibility, polarizability and chemical hardness of the ions and compared with available experimental data. The fact of good agreement between the experimental and computed global hardness of ions and correct demonstration of d-block and f-block contraction by the computed radii are used as benchmark to test the validity of the values of the computed theoretical radii of the ions as their representative sizes. It is concluded that the theoretically computed radii of ions are visualizable size representation of ions and can be used as their absolute radii at the respective oxidation states.
Excited State Proton Transfer of Carbazole. A Convenient Way to Study Microheterogeneous Environments
Authors: Chattopadhyay Nitin
Published: October 2008

Excited state proton transfer of carbazole gives rise to dual fluorescence from the two prototropic species. Simultaneous consideration of the two emissions takes care of many of the instrumental artifacts. The relative intensity of the two emissions of carbazole is sensitive not only to the pH of the bulk medium but also the microenvironment around the probe. Hence, excited state proton transfer of carbazole has been well studied and exploited extensively to study the detail of microheterogeneous liquid environments like aqueous micelles, cyclodextrins etc. Effect of additive like urea has also been monitored via this photoreaction.
Studies on Electronic Charge of the Hydrogen Bond Proton in Model Molecular Systems
Authors: Chojnacki Henryk
Published: October 2008

The population analysis of the hydrogen bond atoms was analyzed within the different basis sets for model molecular systems for the ground and low-lying excited electronic states. The Mulliken, Lőwdin and Hirshfeld methods were used in our investigations. It has been shown that normally the proton is transferred, however, in some excited electronic states the hydrogen atom displacement might be responsible for the tautomeric interconversion.
Modelling of Octahedral Manganese II Complexes with Inorganic Ligands: A Problem with Spin-States
Authors: Trzaskowski Bartosz , Les Andrzej , Adamowicz Ludwik
Published: October 2008

Quantum mechanical ab initio UHF, MP2, MC-SCF and DFT calculations with moderate Gaussian basis sets were performed for MnX6, X = H2O, F-, CN-, manganese octahedral complexes. The correct spin-state of the complexes was obtained only when the counter ions neutralizing the entire complexes were used in the modelling at the B3LYP level of theory.
Structure of Stacked Dimers of N-Methylated Watson–Crick Adenine–Thymine Base Pairs
Authors: Shishkin Oleg V. , Elstner Marcus , Frauenheim Thomas , Suhai Sándor
Published: October 2008

The structure of two isomeric stacked dimers of Watson-Crick 9-methyladenine-1-methylthymine pairs was fully optimized using an approximate density functional theory (DFT) method augmented with an empirical dispersion interaction. The results of the calculations reveal that head-to-tail (AT-TA) and head-to-head (AT-AT) dimers possess a significantly different geometry. The structure of both complexes is stabilized by vertical CH…O and C-H…N hydrogen bonds with the participation of the hydrogen atoms of the methyl groups. The energy of hydrogen bonding and stacking interactions was additionally calculated using the MP2/6-31G*(0.25) method. Differences in the mutual arrangement of the base pairs in two isomeric dimers lead to significant changes of intra and interstrand stacking interaction energies.
Cationic Polymerization of 1,2-Epoxypropane by an Acid Exchanged Montmorillonite Clay in the Presence of Ethylene Glycol
Authors: Yahiaoui Ahmed , Belbachir Mohammed , Hachemaoui Aïcha
Published: October 2008

The polymerization of propylene oxide (PO) catalysed by maghnite-H+ (mag-H+) in the presence of ethylene glycol was investigated. Mag-H+ is a montmorillonite silicate sheet clay was prepared through a straight forward proton exchange process. It was found that the cationic polymerization of PO was initiated by mag-H+ at 20 °C both in bulk and in solution. The effect of the amount of mag-H+ and solvent was studied. These results indicated the cationic nature of the polymerization A possible initiation pathway, via the transfer of protons from mag-H+ to the monomer, is proposed.
Coupled Cluster Calculations of the Ground and Excited Electronic States Using Two- and Four-Component Relativistic Spinors
Authors: Chaudhuri Rajat  K.
Published: October 2008

The coupled cluster based linear response theory which is applicable to the direct calculation of atomic and molecular properties are presented and applied to compute the ionization potentials and excitation energies of light and moderately heavy atoms. The e®ect of electron correlation on the ground and excited states is studied using Hartree-Fock, Dirac-Fock and approximate two-component relativistic spinors.
Structure, Stability and Interaction Studies on Schiff Base Analogue Systems
Authors: Kolandaivel P. , Kanakaraju R.
Published: October 2008

Ab initio and density functional theory methods have been applied to study the molecular structure and interaction of water with N-methyl-2-propenylidenimine and Nmethyl- 2-butenylidenimine molecules. The most possible reactive sites of the above molecules have been identified for the water interactions. The strength of the hydrogen bond is discussed using the atomic charges, which were calculated using the Mulliken population analysis and Natural population analysis schemes at MP2/6-31G* level of theory. The electron density (ρ) and laplacian of electron density (∇2ρ) have been calculated for the possible existence of the hydrogen bonds with CH and CH3 groups of molecules using the “Atoms in molecules” approach. The chemical hardness and chemical potential for these complexes have been calculated at HF/6-31G* level of theory and discussed for the conformational stability of these molecules.
NMR-based Structural Studies of the Glycosylated MUC1 Tandem Repeat Peptide
Authors: Suryanarayanan G. , Keifer P. A. , Wang G. , Kinarsky L. , Hollingsworth M. A. , Sherman S.
Published: October 2008

MUC1 is a glycoprotein that plays an important role in cancer pathogenesis. In order to study the effect of glycosylation on the conformational propensities of the tandem repeat domain of MUC1, we have determined the structure of the MUC1 tandem repeat peptide AHGVTSAPDTRPAPGSTAPP, O-glycosylated with the trisaccharide (α-Glc-1,4-β-Glc-1,4-α-GalNAc-) at Thr5. This glycopeptide was synthesized to model a heavily Oglycosylated threonine residue in the tandem repeat domain. The NMR experiments used in this study included TOCSY, NOESY, ROESY, DQF-COSY, HSQC and 1D NMR. The peak volumes determined using the program SPARKY were converted into distance constraints using the program CALIBA. The programs FiSiNOE and HABAS were used to generate angle constraints. Using conformational restraints obtained from NMR, the program DYANA was used to determine the structures of the peptide. Finally, structural refinement was performed within the SYBYL software package using GLYCAM parameters and Kollman-all atom types. The presence of strong sequential αN connectivities suggested an extended conformation of the peptide backbone. Strong sequential αδ connectivities were indicative of a trans conformation of the Ala-Pro peptide bonds. In addition, presence of sequential NN connectivities in the peptide segments Gly3-Val4-Thr5-Ser6, Asp9-Thr10-Arg11 and Gly-Ser16 were indicative of twist-like conformations of the peptide backbone in these peptide segments.
The Mechanism of Phosphoryl Transfer Reaction and the Role of Active Site Residues on the Basis of Ribokinase-Like Kinases
Authors: Dyguda Edyta , Szefczyk Borys , Sokalski W. Andrzej
Published: October 2008

The role of ribokinase-like carbohydrate kinases consists in ATP dependent phosphorylation of small molecules containing hydroxymethyl group. Although they differ substantially in structural terms and exhibit a broad substrate specificity, some family-wide conserved features can be distinguished suggesting the common mode of action. 4-methyl-5-β-hydroxyethylthiazole kinase (Thz kinase) was chosen as a representative model and the mechanism proposed in X-ray crystal structure paper provided the basis for calculations. In particular, the possible role of several active site residues (Arg121 and Cys198 among others) and of the two magnesium ions was examined. Static and dynamic catalytic fields for the reaction were generated revealing the most favourable environment for the preferential transition state stabilization. An attempt to model the phosphoryl transfer reaction as well as to investigate the influence of the cysteine residue on the reaction course at the semiempirical PM3 level of theory was undertaken.
State Selective Electron Capture in the Collision of S3+ Ions in Atomic Hydrogen and Helium
Authors: Łabuda Marta , Tergiman Y. Suzanne , Bacchus-Montabonel Marie-Christine , Sienkiewicz Jozef E.
Published: October 2008

A full theoretical treatment including an ab-initio molecular calculation of the potential energy curves and couplings followed by a semi-classical collision dynamics has been performed for the one-electron capture by S3+ ions in collision with atomic hydrogen. The present paper completes a previous letter [9] and displays the full results concerning this process in order to provide a detailed understanding of the mechanism. These calculations show evidence of the predominance of the S2+(3s23p3d)3F° capture level, already pointed out by translational energy spectroscopy experiments and confirms experimental measurements. A compared study of the behaviour of the S3+ projectile colliding both hydrogen and helium targets is also presented.
Special Issue Dedicated to Professor Marvin Charton – Correlation Analyst Par Excellence
Authors: Krygowski Tadeusz
Published: October 2008

The collection of papers dedicated to Marvin Charton that we present in this special issue of IJMS covers a variety of fields of scientific research and well represents his wide range of interests – all the contributors are his friends or users of his ideas and the results of his scientific work and have often also been partners in subtle and very fruitful discussions with Marvin.[...]
Marvin Charton - Correlation Analyst Par Excellence
Authors: Shorter John
Published: October 2008

Since the late 1950s Marvin Charton, physical organic chemist, of Pratt Institute, Brooklyn, New York has studied structure-property relationships through correlation analysis, and has become one of the leading authorities in this field.
Kinetics and Mechanism of Acetoxymercuration and Acid-Catalysed Hydration of α-Alkylstyrenes
Authors: Svoboda Jan , Pelcová Monika , Nevěčná Taťjana , Pytela Oldřich
Published: October 2008

Nine α-alkylstyrenes carrying the following substituents have been synthesised: methyl, ethyl, propyl, butyl, pentyl, isobutyl, isopropyl, sec-butyl and tert-butyl. Kinetics has been measured for the reaction of these compounds with mercuric acetate in anhydrous acetic acid at 25 °C. The rate constants are very sensitive to inductive effects (ρI = –49.5 in AISE theory) and steric effects (ψ = –1.59 according to Charton). These results support the presumed existence of an intermediate with an asymmetrically bound acetylmercuric cation to carbon atoms of the vinyl group of styrene. The kinetics of an acid-catalysed hydration of the above-mentioned α-alkylstyrenes were also measured in aqueous sulphuric acid at 25 °C. The derivatives exhibited kinetically a consecutive isomerisation reaction giving the more stable substituted styrenes. The values of the slope m‡m* of the dependence upon the excess acidity function (X) were evaluated, and exceptionally low values were found for the butyl and pentyl substituents (1.02 and 0.73, respectively), while on the other hand tert-butyl showed an exceptionally high value (3.28). On the basis of the facts, a mechanism has been suggested for the acid-catalysed hydration, involving the reaction of a relatively stable and sterically hindered carbocation with water as the rate-limiting step of the reaction.
Solvent and Ligand Effects on the Tandem Addition-Lithiation-Electrophilic Substitution of Phenyllithium on α,β-Unsaturated Carbonyl Compounds
Authors: Nudelman N. Sbarbati , Vázquez Alvaro
Published: October 2008

The reaction of phenyllithium with E-cinnamaldehyde is extremely sensitive to the reaction conditions and surprising changes in the product distribution were observed upon changes in the solvent, concentrations, duration or temperature of the reaction. For these reasons the above mentioned reaction was considered an appropriate model to examine solvent and aggregation effects of PhLi. On the other hand, when two or trhee equiv of phenyllithium are used, instead of one, the reaction transforms into a surprising tandem addition-lithiation-β-alkylation sequence, that can be successfully applied to the synthesis of substituted dihydrochalcones. The observed effects upon changes in the reaction conditions, as well as the effects of additives that modify the PhLi dimer-monomer equilibrium are consistent with a reaction pathway in which dimeric phenyl lithium attacks to the E-cinnamaldehyde without previous deaggregation. Usually, monomers are found to be more reactive than dimers, but, in this reaction the opposite effect is observed, and the tandem reaction spectacularly decreases with the (PhLi)2 concentration.
Octopamine Levels in Blattella Germanica L. Tissues by Capillary Gas Chromatography with Electron Capture Detection
Authors: Pandey Canping , Li Weixi , Wang Yongshan , Jiang Shuren
Published: October 2008

Distribution and levels of octopamine (OA), one of the biogenic amines in the invertebrate nervous system, may have significant effects on insect physiological processes including growth, feeding and reproduction. In this paper capillary gas chromatography with electron capture detection (GC-ECD) and mass selective detection (GC-MS) were used to determine the content of OA in Blattella germanica L. central nervous system (CNS), and that of OA in cockroach stressed by kinds of insecticides, known octopaminergic agonists and some essential oils. A derivatization method for organic extracts via reaction with pentafluoropropionic anhydride (PFPA) was developed. The resulting OA derivatives were confirmed by GC-MS to be tris-pentafluoropropionyl-OA. The method was used to quantify the amount of OA in insect issues by capillary GC-ECD through an extraction-derivatization-liquid/liquid partition procedure. Average OA content in normal cockroaches was determined to be 68.49 ± 7.31 ng/g tissue (N=5 determinations). It was shown that insecticides including chlordimeform, methomyl, permethrin, chlorfluazuron, malathion, trichlorfon and some oxazolidine agonists, essential oils including eugenol, cinnamic alcohol, phenyl ethyl alcohol could led to significant increase of OA levels in the cockroach CNS comparing with which in insect treated by 1-butanone. Malathion, trichlorfon, chlorfluazuron and cinnamic alcohol were shown to be able to cause a 20- fold increase in OA levels.
Tetra-tert-Butyl-di-m-Hydroxo Digallium(III) and 1,12-Diaza-3,4:9,10-Dibenzo-5,8-Dioxo-cyclo-Pentadecane. Structure and Isomers of the Coordination Compound
Authors: Sun Hongsui , Thulstrup Peter W. , Larsen Sine , Larsen Erik
Published: October 2008

Tri-t-butylgallium has been reacted with the macrocycle 1,12-diaza-3,4:9,10-dibenzo-5,8-dioxocyclopentadecane which could be a potential ligand for gallium(III). A reaction product was analyzed and single crystal X-ray diffraction experiments showed that it consisted of the cyclic dimer of di-t-butylgallium-hydroxide hydrogen bonded to the macrocycle. Without a co-crystallized organic molecule di-t-butylgallium hydroxide crystallizes as a trimer. Density functional calculations have been used to predict the structures and the total energies for the monomer, dimer, trimer, and tetramer of dimethylgallium hydroxide in order to provide a basis for the understanding of oligomer population for the dimethylgallium hydroxides. Force field calculations are shown to be able to produce a similar strain energy difference for dimer, trimer, and tetramer forms of (CH3)2Ga(OH) and this method can economically be used for larger alkyl groups. The force field computations show that the trimeric di-t-butyl gallium(III) hydroxide is much more stable than the dimeric form which therefore must owe its existence to the association with the hydrogen-bonded macrocycle.
Location, formation and biosynthetic regulation of cellulases in the gliding bacteria Cytophaga hutchinsonii
Authors: Louime Clifford , Abazinge Michael , Johnson Elijah
Published: October 2008

An analysis of the recently published genome sequence of Cytophagahutchinsonii revealed an unusual collection of genes for an organism that can attackcrystalline cellulose. Consequently, questions were being raised by cellulase scientists, as towhat mechanism this organism uses to degrade its insoluble substrates. Cellulose, being ahighly polymeric compound and insoluble in water, cannot enter the cell walls ofmicroorganisms. Cellulose-degrading enzymes have therefore to be located on the surface ofthe cell wall or released extracellularly. The location of most cellulase enzymes has beenstudied. However, basic information on C. hutchinsonii cellulases is almost non-existent. Inthe present study, the location, formation and biosynthetic regulation of cellulases in C.hutchinsonii were demonstrated on different substrates. Various fractions isolated from C.hutchinsonii after cell rupture were assayed for carboxymethyl-cellulase activity (CMC).The cellulases were found to be predominantly cell-free during active growth on solka-flok,although 30% of activity was recorded on cell-bound enzymes. Relatively little CM-cellulase was formed when cells were grown on glucose and cellobiose. Apparently glucoseor labile substrates such as cellobiose seem to repress the formation of CM-cellulase. Thesefindings should provide some insight into possible hydrolysis mechanisms by C.hutchinsonii.
Predicting Aqueous Solubility of Chlorinated Hydrocarbons by the MCI Approach
Authors: Wang Ying-Long , Hu Yang-Dong , Wu Lian-Ying , An Wei-Zhong
Published: October 2008

Correlation for estimation of the aqueous solubility (logSw) of chlorinatedhydrocarbons molecules is proposed. The MCI based quantitative structure-propertyrelationship (QSPR) model proposed is predictive and requires only three connectivityindices in the calculation. The correlation equation obtained which is based on a training setof 50 chlorinated hydrocarbons has a correlation coefficient of 0.9670 and a standard errorof 0.44 log10 units. Application of the developed model to a testing set of 73 chlorinatedhydrocarbons demonstrates that the new model is reliable with good predictive accuracy andsimple formulation. Besides, the model does not require any experimental physicochemicalproperties in the calculation, so it is easy to apply, especially in cases where it isinconvenient or impossible to measure the physicochemical properties.
Ballistic Protons and Microwave-induced Water Solitons in Bioenergetic Transformations
Authors: Tirosh Reuven
Published: October 2008

Active streaming (AS) of liquid water is considered to generate and overcomepressure gradients, so as to drive cell motility and muscle contraction by hydrauliccompression. This idea had led to reconstitution of cytoplasm streaming and musclecontraction by utilizing the actin-myosin ATPase system in conditions that exclude acontinuous protein network. These reconstitution experiments had disproved a contractileprotein mechanism and inspired a theoretical investigation of the AS hypothesis, aspresented in this article. Here, a molecular quantitative model is constructed for a chemicalreaction that might generate the elementary component of such AS within the pure waterphase. Being guided by the laws of energy and momentum conservation and by the physicalchemistry of water, a vectorial electro-mechano-chemical conversion is considered, asfollows: A ballistic H+ may be released from H2O-H+ at a velocity of 10km/sec, carrying akinetic energy of 0.5 proton*volt. By coherent exchange of microwave photons during 10-10sec, the ballistic proton can induce cooperative precession of about 13300 electrically-polarized water molecule dimers, extending along 0.5 μm. The dynamic dimers rearrangealong the proton path into a pile of non-radiating rings that compose a persistent rowing-likewater soliton. During a life-time of 20 msec, this soliton can generate and overcome amaximal pressure head of 1 kgwt/cm2 at a streaming velocity of 25 μm/sec and intrinsicpower density of 5 Watt/cm3. In this view, the actin-myosin ATPase is proposed to catalyzestereo-specific cleavage of H2O-H+ , so as to generate unidirectional fluxes of ballisticprotons and water solitons along each actin filament. Critical requirements and evidentialpredictions precipitate consistent implications to the physical chemistry of water, enzymatichydrolysis and synthesis of ATP, trans-membrane signaling, intracellular transport, cellmotility, intercellular interaction, and associated electro-physiological function. Sarcomerecontraction is described as hydraulic compression, driven by the suction power of centrally-oriented AS. This hydraulic mechanism anticipates structural, biochemical, mechanical and energetic aspects of striated muscle contraction, leading to quantitative formulation of a hydrodynamic power-balance equation yielding a general force-velocity relation.
Interaction of Plant Epicuticular Waxes and Extracellular Esterases of Curvularia eragrostidis during Infection of Digitaria sanguinalis and Festuca arundinacea by the Fungus
Authors: Wang Fei , Zhang Peng , Qiang Sheng , Xu Lang-Lai
Published: October 2008

Curvularia eragrostidis, a causal agent of head blight on the weed (Digitariasanguinalis), did not cause disease on the turfgrass Festuca arundinacea. Differentextracellular esterase isoenzymes were detected in saprophytic and parasitic phases duringthe fungal germination. The epicuticular waxes of D. sanguinalis were more efficient toinduce the secretion of esterases from the fungus than that of F. arundinacea, but were morerapidly degraded by the fungal enzymes. Component analysis indicated that the epicuticularwaxes from D. sanguinalis were mostly composed of alcohols, with 54.3% being 9,12-Octadecadien-1-ol. The main component of F arundinacea waxes was alkyl compounds,with 49.8% being olefin, 9-Tricosence. More long-chained esters were found in D.sanguinalis waxes, which were easier to be digested than those in F. arundinacea waxes byextreacellular esterases of the fungus. Epicuticular waxes play a role in varyingpathogenicity of C. eragrostidis on D. sanguinalis and F arundinacea.
Isolation and Characterization of a Novel Four-Transmembrane Protein PMP22CD Specifically Expressed in the Testis
Authors: Wang Minghua , Luo Guanmei , Li Fang , Wu Shiliang , Jiang Juxiang , Huang Chaoqun
Published: October 2008

PMP22_Claudin family proteins play important roles in cell tight junction. In thisstudy, we have identified a novel member of this family, PMP22CD. Human PMP22CD wasfirst discovered by database sequence mining and analysis, and verified by cloning andsequencing. PMP22CD was isolated from the human testis cDNA library and mapped tochromosome 11q24.1 by browsing the UCSC genomic database. It contains an ORF with alength of 675bp, encoding a protein that contains a putative PMP22_Claudin domain withfour transmembrane helices. Its molecular weight and isoelectric point are predicted to be25.8kDa and 8.42, respectively. The PMP22CD protein is highly conservative in mammalanimals. Phylogenetic tree analysis indicated that PMP22CD stands for a new subgroup inthe PMP22/EMP/Claudin family. RT-PCR analysis showed that PMP22CD was specificallyexpressed in the testis. Green fluorescence protein localization analysis showed thatPMP22CD mainly surrounded the nuclear membrane, with a minority distribution in thecytoplasm. These results suggested that PMP22CD is a distant member of thePMP22/EMP/Claudin family and that it may have a novel function that does not involve celltight junction because it is not located at the cell membrane.
Additional Solvent Ionizing Power Values for Binary Water- 1,1,1,3,3,3-Hexafluoro-2-propanol Solvents
Authors: Kevill Dennis  N. , Ryu Zoon   Ha
Published: October 2008

Determinations of the specific rates of solvolysis of 1-adamantyl bromide and 1-adamantyl iodide in 1,1,1,3,3,3-hexafluoro-2-propanol-water mixtures, in conjunction withearlier reported values in 80% ethanol, have led to additional YBr and YI solvent ionizingpower values. These new values will be especially important in avoiding multicollinearitywhen the extended Grunwald-Winstein equation (extended by addition of a term involvingsolvent nucleophilicity) is used to correlate solvent-induced changes in the specific rates ofsolvolyses involving a bromide or iodide ion leaving group.
Understanding the Selectivity Mechanism of the Human Asialoglycoprotein Receptor (ASGP-R) toward Gal- and Man- type Ligands for Predicting Interactions with Exogenous Sugars
Authors: Massarelli Ilaria , Murgia Laura , Bianucci Anna Maria , Chiellini Federica , Chiellini Emo
Published: October 2008

A practical approach for addressing the computer simulation of protein-carbohydrate interactions is described here. An articulated computational protocol was setup and validated by checking its ability to predict experimental data, available in theliterature, and concerning the selectivity shown by the Carbohydrate Recognition Domain(CRD) of the human asialoglycoprotein receptor (ASGP-R) toward Gal-type ligands. Somerequired features responsible for the interactions were identified. Subsequently the sameprotocol was applied to monomer sugar molecules that constitute the building blocks foralginates and ulvans. Such sugar polymers may supply a low-cost source of rare sugars witha potential impact on several industrial applications, from pharmaceutical to fine chemicalindustry. An example of their applicative exploitation could be given by their use indeveloping biomaterial with adhesion properties toward hepatocytes, through interactionwith the ASGP-R. Such a receptor has been already proposed as a target for exogenousmolecules, specifically in the case of hepatocytes, for diagnostic and therapeutic purposes.The DOCK5.2 program was used to search optimal locations of the above ligands of interestinto CRD binding site and to roughly estimate interaction energies. Finally, the binding ∆G oftheoretical protein-ligand complexes was estimated by using the DelPhi program in which thesolvation free energy is accounted for with a continuum solvent model, by solving the Poisson-Boltzmann equation. The structure analysis of the obtained complexes and their ∆G values suggest that one of the sugar monomers of interest shows the desired characteristics.
Cell Adhesion Regulates Expression of the Androgen Receptor and Coregulators in Different Prostate Cancer Cells
Authors: Zhang Jie , Xiang Jia-Qing , Zhang Ya-Wei , Chen Yan-Yan , Zhou Xiao-Yan , Liu Yun , Li Sheng
Published: October 2008

Prostate cancer cells adhere to a tumor basement membrane, while secretoryepithelial cells reside in a suprabasal cell compartment. Since tumor cells are derived fromsuprabasal epithelial cells, they experience de-novo substratum adhesion in the context ofoncogenesis. We therefore analyzed whether cell-matrix adhesion could affect the proteinexpression and activity of the AR. In this study, AR protein expression declined uponsuspension of BPH-1-AR cells, but not in PC-3-AR cells shown by Western blot. In a timecourse study, BPH-1 cell lost AR expression within 6 hours, and the synthetic androgen,R1881 reduced the loss of AR expression. We further explored the mechanism of AR loss insuspended BPH-1 cells. BPH-1-AR cells underwent apoptosis (anoikis) when suspended for2 - 5 hours. Suspension did not induce significant apoptosis or decreasing of AR expressionin PC-3 cells. Inhibition of apoptosis in suspended BPH-1-AR cells, either by expression ofBcl-2 or Bcl-xl or by treatment with Z-VAD, a caspase inhibitor, prevented loss of ARprotein. In contrast, the calpain protease inhibitor , ALLN, accelerated the loss of AR proteinexpression. Additionally, cell-matrix adhesion changed the expression of coregulators of ARin the mRNA level of prostate cancer cells. Our results demonstrate that AR proteinexpression was reduced through activation of cell death pathways, and thus indirectly through cell suspension in BPH-AR cells. The activity of AR can also be regulated by adhesion in PC-3-AR and LNCaP cells through affecting the coregulators level.
Antiproliferative Activity of β-Hydroxy-β-Arylalkanoic Acids
Authors: Dilber Sanda P. , Žižak Željko S. , Stanojković Tatjana P. , Juranić Zorica D. , Drakulić Branko J. , Juranić Ivan O.
Published: October 2008

Article describes the synthesis of fifteen β-hydroxy-β-arylalkanoic acids byReformatsky reaction using the 1-ethoxyethyl-2-bromoalkanoates, aromatic or cycloalkylketones or aromatic aldehydes. The short survey of previously reported synthetic proceduresfor title compounds, is given. The majority of obtained compounds exert antiproliferativeactivity in vitro toward human: HeLa, Fem-X cells, K562, and LS174 cells, having IC50values from 62.20 to 205 μM. The most active compound is 3-OH-2,2-di-Me-3-(4-biphenylyl)-butanoic acid, having the IC50 value 62.20 μM toward HeLa cells. Sevenexamined compounds did not affect proliferation of healthy human blood peripheralmononuclear cells (PBMC and PBMC PHA), IC50 > 300 μM. The preliminary QSARresults show that estimated lipophilicity of compounds influences their antiproliferativeactivity in the first place. The ability of dehydration, and the spatial arrangement ofhydrophobic portion, HBD and HBA in molecules are has almost equal importance aslipophilicity.
Effects of Acetazolamide Combined with or without NaHCO3 on Suppressing Neoplasm Growth, Metastasis and Aquaporin-1 (AQP1) Protein Expression
Authors: Li Xue-Jun , Xiang Yang , Ma Bing , Qi Xiao-Qiang
Published: October 2008

This study was made to explore the effects of acetazolamide on tumor growth,metastasis and the possible mechanisms. The mice bearing with Lewis lung carcinomaswere taken as the animal model. The effects of acetazolamide were compared with thecombination treatment of NaHCO3 on tumor growth, metastasis and carbonic anhydraseactivity in lung and tumor tissues using imidazole-Tris technique. And also the possible roleof AQP1 in tumor tissues was investigated by Western blot and immuno-histochemicalanalysis. Results showed that acetazolamide alone could sharply reduce the number of lungmetastasis and primary tumor growth, and appeared in a dose-dependent manner.Acetazolamide significantly inhibited carbonic anhydrase activity in tumor tissue. After theaddition of NaHCO3, the suppression of acetazolamide on tumor growth, number ofmetastasis and carbonic anhydrase activity in primary tumor tissue could not be alteredsignificantly, but the inhibitory rate of metastasis in lung and carbonic anhydrase activity inlung tissue appeared to show a reversal trend in the dose dependency from the acetazolamidetreatment alone. The exactly mechanisms need to be clarified in future. Western blot andimmunohistochemical analysis demonstrated that AQP1 expression in the tumor tissue washigher than both tissue of normal and treated with acetazolamide treatment alone.Combination with NaHCO3 could not synergistically inhibit the expression of AQP1 withacetazolamide. The results suggested that the mechanism of acetazolamide on anti-tumor especially on its anti-metastasis actions might partly involve either inhibiting the carbonic anhydrase activity or reducing AQP1 water channel protein expression, whatever if treated with or without NaHCO3.
Imprinting Status of IGF2 in Cord Blood Cells of Han Chinese Newborns
Authors: Dai Yimin , Wang Zhiqun , Li Jie , Gu Xiangfang , Zheng Mingming , Zhou Jianjun , Ye Xiaodong , Yao Jincui , Cui Isabelle , Hu Yali , Cui Hengmi
Published: October 2008

Loss of imprinting (LOI) of insulin-like growth factor II gene (IGF2) is anepigenetic abnormality associated with human diseases. However, little is known about thecharacteristics of IGF2 imprinting in newborn cord blood cells. METHODS: A total of 923cord blood samples from term singletons and related clinical data were collected; IGF2imprinting status in 273 specimens were successfully analyzed using RT-PCR andrestriction fragment length polymorphism. RESULTS: LOI of IGF2 was detected in 20.9%of informative samples. The mean birth weights (BW) in the LOI and the normal imprintinggroups were 3462.7 ± 460.2 g and 3363.7 ± 427.7 g, respectively. The abdominal perimetersin the LOI group tended to be larger than that in the normal imprinting group. Pregnancycomplications, delivery modes, newborn diseases, occurrences of malignant tumors ingrandparents, and other maternal factors were not associated with LOI of IGF2. 22.2% ofthe infants with IGF2 LOI also showed LOI in their father’s lymphocytes while 21.4% intheir mother’s lymphocytes. CONCLUSIONS: About 20% of Han Chinese newbornsindicated LOI of IGF2 in their cord blood lymphocytes that may represent the epigeneticcharacteristics in this ethnic group. While IGF2 LOI tends to be weakly inherited between parents and offspring, abnormal imprinting seems to be statistically unrelated with phenotypes of newborns, although it might have an association with later phenotypes of infants.
Sulfonium-based Ionic Liquids Incorporating the Allyl Functionality
Authors: Zhao Dongbin , Fei Zhaofu , Ang Wee Han , Dyson Paul J.
Published: October 2008

A series of sulfonium halides bearing allyl groups have been prepared andcharacterized. Anion metathesis with Li[Tf2N] and Ag[N(CN)2] resulted in sulfonium-basedionic liquids which exhibit low viscosities at room temperature. The solid state structure ofone of the halide salts was determined by single crystal X-ray diffraction.
How Good Can the Characteristic Polynomial Be for Correlations?
Authors: Bolboaca Sorana Daniela , Jantschi Lorentz
Published: October 2008

The aim of this study was to investigate the characteristic polynomials resulting from the molecular graphs used as molecular descriptors in the characterization of the properties of chemical compounds. A formal calculus method is proposed in order to identify the value of the characteristic polynomial parameters for which the extremum values of the squared correlation coefficient are obtained in univariate regression models. The developed calculation algorithm was applied to a sample of nonane isomers. The obtained results revealed that the proposed method produced an accurate and unique solution for the best relationship between the characteristic polynomial as molecular descriptor and the property of interest.
Correlations of the Specific Rates of Solvolysis of Aromatic Carbamoyl Chlorides, Chloroformates, Chlorothionoformates, and Chlorodithioformates Revisited
Authors: Kevill Dennis N. , Koyoshi Fumie , D’Souza Malcolm J.
Published: October 2008

Additional specific rates of solvolysis are determined for phenyl chloroformate.These values are combined with literature values to give a total of 49 data points, which areused within simple and extended Grunwald-Winstein treatments. Literature values are alsobrought together to allow treatments in more solvents than previously for three N-aryl-N-methylcarbamoyl chlorides, phenyl chlorothionoformate, phenyl chlorodithioformate, andN,N-diphenylcarbamoyl chloride. For the last two listed, moderately strong evidence for ameaningful inclusion of a term governed by the aromatic ring parameter (I) was indicated.No evidence was found requiring inclusion of this parameter for ionization reactions withonly one aromatic ring on the nitrogen of carbamoyl chlorides or for the solvolyses of thechloroformate or chlorothionoformate proceeding by an addition-elimination (association-dissociation) mechanism.
Changes in the Ratio of Tc1/Tc2 and Th1/Th2 Cells but Not in Subtypes of NK-Cells in Preeclampsia
Authors: Hu Yali , Zhou Jianjun , Hao Sha , Wang Zhiqun , Dai Yiming , Ling Jingxian , Hou Yayi
Published: October 2008

It has been suggested that natural killer (NK) cell activity and Th1 immunitymay be involved in the pathogenesis of preeclampsia. This study aimed to investigate theimmunophenotypes of NK cells and type 1/type 2 immunity in both decidua and maternalperipheral blood between normal (n=11) and preeclamptic pregnant women (n=20) by flowcytometry. The results showed that no significant difference was observed between patientsand controls by detecting CD56+ CD69+ and CD56+ CD94+ NK cells in both peripheralblood and decidua. Moreover, in preeclamptic patients, decreased percentages of Tc2 andTh2 cells and the increased ratios of Tc1/Tc2 were determined in both decidua andmaternal peripheral blood. In addition, the ratio of Th1/Th2 in peripheral blood alsoincreased. There was no significant difference of immunophenotypes of uNK cells betweenpreeclampsia and normal pregnancy. Local decidua and systematic immunity did notcorrelate with each other. These results suggest that the type 1/type 2 immunity shifted totype 1 immunity including Th1 and Tc1 cells may contribute to the patho-genesis ofpreeclampsia.
Irradiation Effect on Oxidative Condition and Tocopherol Content of Vegetable Oils
Authors: Lalas Stavros , Gortzi Olga , Tsaknis John , Sflomos Konstantinos
Published: October 2008

The effect on induction period and tocopherol content after γ-irradiation onsamples of olive oil and seed oils (sunflower and soybean) was determined. In seed oilsamples 0, 100, 200 and 300 ppm of δ-tocopherol were added before irradiation with 1, 2and 3kGy. The results of induction period showed that, after irradiation, all samplespresented a significant decreased in resistance to oxidation. However, this decrease wasminimized when δ-tocopherol was added. Irradiation significantly decreased the level oftocopherols. δ-Tocopherol appeared more sensitive in irradiation process than α- andγ-tocopherol. The addition of δ-tocopherol significantly reduced, in most cases, thedepletion of the other tocopherols.
DNA-Binding Study of Tetraaqua-bis(p-nitrobenzoato)cobalt(II) Dihydrate Complex: [Co(H2O)4(p-NO2C6H4COO)2]·2H2O
Authors: Arslantas Ali , Devrim A. Kadir , Necefoglu Hacali
Published: October 2008

The interaction of [Co(H2O)4(p-NO2C6H4COO)2]. 2H2O with sheep genomicDNA has been investigated by spectroscopic studies and electrophoresis measurements.The interaction between cobalt(II) p-nitrobenzoate and DNA has been followed by gelelectrophoresis while the concentration of the complex was increased from 0 to 14 mM.The spectroscopic study and electrophoretic experiments support the fact that the complexbinds to DNA by intercalation via p-nitrobenzoate into the base pairs of DNA. Themobility of the bands decreased as the concentration of complex was increased, indicatingthat there was increase in interaction between the metal ion and DNA.
Antioxidant Activity of a Series of FluorinatedPyrano-nucleoside Analogues of N4-benzoyl Cytosine andN6-benzoyl Adenine
Authors: Spanou Chrysoula , Manta Stella , Komiotis Dimitri , Dervishi Albiona , Kouretas Demetrios
Published: October 2008

Fluorinated nucleoside analogues are known as antitumor, antiviral andchemotherapeutic agents, although the antioxidant activity of this kind of molecules is notyet investigated. In this study we have tested the antioxidant activity of a series of modifiedpyrano-nucleoside analogues using three in vitro assays. Firstly, the antioxidant capacity ofthe products was assessed using the DPPH assay and secondly, in order to examine theability of the products to protect DNA from the activity of reactive oxygen species (ROS),a peroxyl radical (ROO•) and a hydroxyl radical (OH•) induced DNA strand scission assaywere used. None of the molecules showed the ability to scavenge DPPH radical andprevent OH• induced DNA strand breakage. Although, most of the tested nucleosideanalogues, had the ability to prevent ROO• induced DNA damage.
Electrochemical Recognition of Metalloproteins by Bromide-modified Silver Electrode - A New Method
Authors: Rezaei-Zarchi Saeed , Saboury Ali Akbar , Norouzi Parviz , Hong Jun , Barzegar Abolfazl , Ganjali Mohammad Reza , Ghourchian Hedayatollah , Moosavi-Movahedi Ali Akbar , Javed Aisha , Rostami Abbas Ali
Published: October 2008

A bromide–modified silver electrode is reported, in the present study, to catalyzethe redox reactions of metalloproteins. This study describes that the bromide ions showvery good redox behavior with silver electrode. The cathodic and anodic peak potentialswere related to the concentration of bromide ions involved in making bromide-modifiedsilver electrode. The electrode reaction in the bromine solution was a diffusion-controlledprocess. Positive potential shift of the bromide ions was seen when different proteins wereadded to the solution using a silver electrode. New cathodic and anodic peaks wereobserved at different potential ranges for myoglobin, cytochrome c and catalase. A linearlyincreasing cathodic peak current of bromide ions was seen when the concentration ofsuperoxide dismutase was increased in the test solution. However, no change for albuminwas observed when its concentration was increased in the test solution. Present data provesour methodology as an easy-to-use analysis for comparing the redox potentials of differentmetalloproteins and differentiating the metallo- from non-metalloproteins. In this study, weintroduced an interesting method for bio-electrochemical analyses.
Consideration of the Factors Influencing the Specific Rates of Solvolysis of p-Methoxyphenyl Chloroformate
Authors: D’Souza Malcolm J. , Reed Darneisha , Koyoshi Fumie , Kevill Dennis N.
Published: October 2008

A recent correlations analysis of the specific rates of solvolysis of p-methoxyphenyl chloroformate (1) in 31 solvents using the three-term Grunwald-Winsteinequation led to a sensitivity (h) towards changes in the aromatic ring parameter (I) of0.85 0.15. This value, suggesting an appreciable contribution from the hI term, is incontrast to the h value of 0.35 0.19 that was reported for the parent phenyl chloroformate(2). However, for 1, only two specific rate values were available for the importantfluoroalcohol containing solvents. Values are now reported for 13 additional solvents,12 of which have appreciable fluoroalcohol content. With all 44 solvents considered, it isfound that the solvolytic behavior indicated for 1 now parallels very closely that previouslyreported for 2.
Photoresist Derived Carbon for Growth and Differentiation of Neuronal Cells
Authors: Zhou Hong , Zhou Jianhua , Gupta Anju , Zou Tie
Published: October 2008

Apoptosis or necrosis of neurons in the central nervous system (CNS) is thehallmark of many neurodegenerative diseases and Traumatic Brain Injury (TBI). Theinability to regenerate in CNS offers little hope for naturally repairing the damagedneurons. However, with the rapid development of new technologies, regenerative medicineoffers great promises to patients with these disorders. Among many events for furtheradvancement of regenerative medicine, extracellular matrix (ECM) plays a critical role forcellular migration and differentiation. To develop a biocompatible and electricallyconductive substrate that can be potentially used to promote growth and regeneration ofneurons and to record intracellular and multisite signals from brain as a probe, a polymericprecursor – SPR 220.7 was fabricated by pyrolysis at temperatures higher than 700 oC.Human Neuroblastoma cells - SK-N-MC, SY5Y, mouse teratocarcinoma cells P-19 and ratPC12 cells were found to attach and proliferate on photoresist derived carbon film.Significantly, neuronal differentiation of PC12 cells induced by NGF was demonstrated byobserving cell shape and size, and measuring the length of neurites under SEM. Our resultsindicated that fabricated carbon could potentially be explored in regenerative medicine forpromoting neuronal growth and differentiation in CNS with neurodegeneration.
Three Dimensional Pharmacophore Modelling of Monoamine oxidase-A (MAO-A) inhibitors
Authors: Sairam Kalapatapu V.V.M. , Khar Roop K. , Mukherjee Rama , Jain Swatantra K.
Published: October 2008

Flavoprotein monoamine oxidase is located on the outer membrane ofmitochondria. It catalyzes oxidative deamination of monoamine neurotransmitters such asserotonin, norepinephrine and dopamine and hence is a target enzyme for antidepressantdrugs. MAO (mono amine oxidase) has two isoforms, namely MAO-A and MAO-B.MAO-A isoform has higher affinity for serotonin and norepinephrine, while; MAO-Bpreferentially deaminates phenylethylamine and benzylamine. These important propertiesdetermine the clinical importance of MAO inhibitors. Selective MAO-A inhibitors are usedin the treatment of neurological disorders such as depression. In this article we havedeveloped a Hypogen pharmacophore for a set of 64 coumarin analogs and tried to analyzethe intermolecular H-bonds with receptor structure.