bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantitative Structure‐Activity Relationships of Phencyclidine Receptor Ligands. Part 2 [1]. Extension of the Scope of the DVDP Parameter
Authors: Hayakawa Naohiro , Inami Yoshiharu , Terada Yukimasa 
Published: October 2006

AbstractThe validity of a parameter, which represents the direction of the molecular dipole vector of phencyclidine (PCP) derivatives, was reviewed. This parameter, named DVDP, quantitatively predicted the receptor binding activity of various PCP analogues. DVDP also effectively explained the activity of remarkably different compounds such as the MK‐801 derivatives. For the comparison of the dipole direction, the arrangement of the molecules was investigated by superimposition. The molecules were superimposed on hypothetical receptor points that were assumed on the characteristic pharmacophores of centrally acting drugs. However, for the MK‐801 derivatives, the superimposition based on the steric overlapping volume and the electrostatic repulsion was dominant. The study confirmed the importance of the hydrocarbon portion of the PCP piperidine ring and suggested an opposite orientation of MK‐801 to the conventional 3‐point model.
Hydrophobicity of Heterocycles: Determination of the π Values of Substituents on N‐Phenylpyrazoles
Authors: Gago Federico , Pastor Manuel , Pérez‐Butragueño Javier , López Raquel , Alvarez‐Builla Julio , Elguero Joseé 
Published: October 2006

AbstractHPLC retention (log k′) and hydrophobic parameter (log Po/w) have been determined for 66 N‐phenylpyrazole derivatives with different substitution patterns, and πpyrazole constants have been calculated for several substituents in the positions 3‐, 4‐ and 5‐ of pyrazole. A linear relationship has been found between πpyrazole and the classical πbenzene constants. The data obtained can greatly improve the quality of QSAR equations involving pyrazole derivatives.
A QSAR Study of Quinolones Based on Electrotopological State Index for Atoms
Authors: Llorente B. , Rivero N. , Carrasco R. , Martinez R. S. , Estrada E. 
Published: October 2006

AbstractA series of 18 quinolone antibacterials were used in a quantitative structure‐activity relationship (QSAR) study based on electrotopological state (E‐state) index for atoms. The results were correlated with minimum inhibitory concentrations (MICs) against E. coli H560 and the DNA gyrase cleavage values. The QSAR equations indicated that the in vitro antibacterial activity was strongly dependent on the E‐state indexes for the atom at position 6 and the O(sp2) of the carbonyl and carboxyl groups. This suggests the possibility of an electrostatic interaction between the atom at position 6 and the receptor; as well as the formation of hydrogen bonds between the carbonyl groups of the quinolone and the receptor.
Computer‐Assisted Analysis of Histamine H2− and H3‐Receptor Agonists
Authors: Sippl Wolfgang , Stark Holger , Höltje Hans‐Dieter 
Published: October 2006

AbstractUsing molecular modelling methods the structural and conformational requirements for receptor affinity and activity of histamine H2‐ and H3‐receptor agonists have been investigated. Two pharmacophore models were derived which indicate the different sterical requirements for the two histamine receptor subtypes. On the basis of these results we suggest that histamine may interact in different bioactive conformations with the corresponding receptor subtypes. Subsequent investigations of the molecular interaction potentials support the described orientations and conformations of H2‐ and H3‐agonists. The derived pharmacophore models together with the molecular interaction patterns of the agonists may serve as basis for amino acid models of the binding regions of H2‐ and H3‐receptor sites.
QSAR Modelling of the Toxicity of some Technical Non‐ionic Surfactants towards Fairy Shrimps
Authors: Lindgren Åsa , Sjöström Michael , Wold Svante 
Published: October 2006

AbstractThe toxicity of a number of non‐ionic surfactants towards Thamnocephalus platyurus (sweet water fairy shrimp) has been examined. The measurements have been performed with the use of so‐called Toxkits, and the results have been expressed both as a mean LC50 value for each of the surfactants, and with a relative scale estimated using of multi dimensional scaling (MDS). An algorithm is shown in matlab code, with which it is possible to perform MDS on a difference matrix with a lot of systematically missing values. The thus obtained results have been combined with the physico‐chemical data for the surfactants, and QSAR models have been estimated for the toxicity (log(LC50)) of the surfactants. The physico‐chemical properties with the main influence on the models were the hydrophilic‐lipophilic‐balance (HLB), the hydrophobicity (log P), the critical micellar concentration (CMC) and the number of carbon atoms in the hydrophobic part (C) of the surfactant.
Three‐dimensional Quantitative Structure–Activity Relationships of Hallucinogenic Phenylalkanamine and Tryptamine Derivatives: Studies using Comparative Molecular Field Analysis (CoMFA)
Authors: Beuerle Gerald , Kovar Karl‐Artur , Schulze‐Alexandru Meike 
Published: October 2006

AbstractInvestigations of the quantitative structure–activity relationships of a data set comprising 66 phenylalkanamines have been carried out using the CoMFA method. This yielded a cross‐validated correlation coefficient (q2 value) of more than 0.8. The target parameter used was the hallucinogenic effect on humans, since this variable is of particular importance for research into addictive substances. It was possible to confirm the reliability of the CoMFA analysis by using a second, independent phenylalkanamine data set. It was found that models with good predictive properties are obtained if up to ten components are taken into account. In a further step it was possible to include hallucinogenic tryptamine derivatives in a common QSAR analysis with the phenylalkanamines and this in spite of their differing basic structures. The final model from that the CoMFA plots were extracted is based on 148 compounds and permits precise inferences to be made concerning the relationships between structural elements and hallucinogenic effects.
Enhancing the Effectiveness of Ligand‐Based Virtual Screening Using Data Fusion
Authors: Willett Peter 
Published: October 2006

AbstractData fusion is being increasingly used to combine the outputs of different types of sensors. This paper reviews the application of the approach to ligand‐based virtual screening, where the sensors to be combined are functions that score molecules in a database on their likelihood of exhibiting some required biological activity. Much of the literature to date involves the combination of multiple similarity searches, although there is also an increasing interest in the combination of multiple machine‐learning techniques. Both approaches are reviewed here, focusing on the extent to which fusion can improve the effectiveness of searching when compared with a single screening mechanism, and on the reasons that have been suggested for the observed performance enhancement.
Implementation of a framework for development of teaching material using distributed sharing virtual space
Authors: Sasaki Hitoshi , Iwasaki Shoichi , Takeya Makoto 
Published: October 2006

AbstractRecently, computer networks have been actively used at educational sites for WBT (Web‐based teaching) and the like. Teachers are trying to develop teaching materials and actively use them in the classroom. The development of teaching materials by 3D CG, actively utilizing the computer graphics functions, has also been started. However, since specialized knowledge and viewpoints are required in developing 3D teaching materials, this development is not easy compared to teaching materials development for WBT and the like. Nor is the environment for utilizing the materials unified. From this viewpoint, this paper proposes a framework for teaching materials development which facilitates the development of 3D teaching materials in the distributed sharing virtual space and realizes the collaborative utilization of multiple teaching materials on a network. The proposed scheme and the teaching materials developed by conventional methods are compared and the effectiveness of the proposed system in the development of teaching materials is discussed. © 2006 Wiley Periodicals, Inc. Syst Comp Jpn, 37(14): 97–106, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10607
Manipulating and imaging individual membrane proteins by AFM
Authors: Gonçalves Rui Pedro , Scheuring Simon 
Published: October 2006

AbstractMembrane proteins are nanometric machines fulfilling defined functions in the membranes of all living cells. They work as transporters, linkers, adhesion molecules, channels, pumps, receptors and enzymes, and in bio‐energetic machineries, to name only a few tasks. In agreement with their multiple functions and importance, it was found that about 25% of all genes code for membrane proteins in organisms ranging from bacteria to humans. Biologists now have a set of techniques such as X‐ray crystallography, electron microscopy, and atomic force microscopy to analyze membrane protein structure, and techniques such as patch‐clamp, black lipid membrane and spectroscopy on membrane vesicles to analyze membrane function. Atomic force microscopy is widely used for imaging and force measurements, and here, its use as a unique tool to nano‐manipulate individual membrane proteins is reviewed. In this ‘mode’, additional loading forces are applied to an imaging tip, and scan rates and feedback parameters are adjusted to deliberately act on the surface of the biological object. When additional loading forces are relatively high (∼500 pN), stacked membrane layers can be dissected to give access to underlying membranes. Similarly, subunits from a multi‐protein complex can be dissected at slightly increased forces (∼200 pN) allowing the analysis of underlying protein structures, and hence that of the complex architecture. At low additional loading forces (∼100 pN), individual protein loops can be manipulated. Importantly, this process is nondestructive and provides access for the analysis of flexible protein surface domains. Copyright © 2006 John Wiley & Sons, Ltd.
The application of two‐dimensional correlation spectroscopy to surface and interfacial analysis
Authors: Dluhy Richard , Shanmukh Saratchandra , Morita Shin‐Ichi 
Published: October 2006

AbstractGeneralized two‐dimensional correlation spectroscopy (2D COS) is a modern analytical tool that is increasingly being used in the interpretation of complex spectra that have broad, multiply overlapped spectral features. Besides functioning as a spectral resolution–enhancement tool similar to curve‐fitting or deconvolution, 2D COS possesses an additional advantage in that it is capable of discerning temporal relationships between intensity variations within a set of spectra. Infrared reflection‐absorbance spectroscopy (IRRAS) at the air–water interface has been a very useful technique in studying the structure of biologically relevant molecules and the interaction between components of biological membranes in an environment close to what is found in nature. To better understand interfacial bio‐mimetic structure, 2D COS can be applied to the IRRAS spectra to analyze changes in infrared intensities as a function of an environmental perturbation such as a change in temperature or surface pressure. To overcome some of the inherent limitations of the generalized 2D method, model‐based approaches such as βν‐ and kν‐correlation analyses and the global 2D phase angle method were developed. This review discusses some of the recent applications of these novel methods to Langmuir monolayers of phospholipids and proteins at the air–water interface and Langmuir–Blodgett polymer films. Copyright © 2006 John Wiley & Sons, Ltd.
Controlling protein retention on enzyme‐responsive surfaces
Authors: Rawsterne Rachel E. , Gough Julie E. , Rutten Frank J. M. , Pham Nhan T. , Poon Wilson C. K. , Flitsch Sabine L. , Maltman Beatrice , Alexander Morgan R. , Ulijn Rein V. 
Published: October 2006

AbstractThe ability to change the properties of solid surfaces on demand is a key component of a multitude of established and emerging technologies. Stimuli that have previously been used to trigger changes in surface properties include changes in solvent, light, pH, ionic strength, temperature and magnetic or electric fields. We are interested in developing surfaces that can be triggered by the catalytic action of enzymes. We demonstrate the selective protease (α‐chymotrypsin and thermolysin) catalysed peptide hydrolysis of surface‐tethered fluorenylmethoxycarbonyl‐dipeptides. We highlight some of the challenges evident from surface analysis in overcoming enzyme retention to the surface addressed by physical adsorption of soluble PEG200 to the surface prior to enzyme exposure. Analysis by ToF‐SIMS and XPS shows that α‐chymotrypsin is deposited and retained on the surfaces and that thermolysin, a much more stable enzyme, selectively cleaves the tethered peptides as intended, and is removed from the surface by washing. Copyright © 2006 John Wiley & Sons, Ltd.
Biodegradation of recalcitrant chlorophenols by cometabolism
Authors: Liu D. , Maguire R. J. , Pacepavicius G. , Dutka B. J. 
Published: October 2006

AbstractUnder normal conditions in the environment a significant proportion of xenobiotic biodegradation involves cometabolism. Using the cometabolic principle, a procedure was developed to achieve accelerated biodegradation of persistent chemicals. Three stable chlorophenols [3,5‐dichlorophenol (DCP), 3,4,5‐trichlorophenol (TCP), and 2,3,5,6‐tetrachlorophenol (TRCP)], which showed a total resistance to the biodegradation potential of a pentachlorophenol‐degrading bacterial culture, were found to be biodegradable using the cometabolic technique. When a low‐chlorinated monochlorophenol (3‐MCP) was the cometabolite, only the medium‐low chlorinated 3,5‐DCP was biodegraded, while the medium chlorinated 3,4,5‐TCP and the medium‐high chlorinated 2,3,5,6,‐TRCP were not degraded by the culture. However, all three stable chlorophenols could be rapidly biodegraded when a highly chlorinated pentachlorophenol (PCP) cometabolite was used. If dual cometabolites (3‐MCP and PCP) were used, all three stable chlorophenols were biodegraded, but at much slower rate. Maximizing biodegradation by use of the cometabolic technique to achieve accelerated biodegradation of stable chemicals is discussed.
Microbial water quality concerns for water supply use
Authors: Geldreich Edwin E. 
Published: October 2006

AbstractThe greatest impact of water pollution on public health comes through drinking water, the source of which may be degraded by point and nonpoint pollution sources including municipal wastewater, storm water runoff, agricultural drainage, and food processing. While water treatment technology can successfully process poor quality source waters containing in excess of 2000 fecal coliforms/100 mL to produce potable water that meets the accepted drinking water standards, there is serious concern that the barriers to microbial breakthrough in the finished water may prove to be dangerously thin. Any momentary break in the treatment train could allow substantial levels of microorganisms to enter the final product—potable water.The burden of water quality enhancement should be a shared responsibility among all discharges and downstream users of these irreplaceable resources. Much can be accomplished through the application of a multiple barrier approach in wastewater treatment, controlled storm water releases, and water supply enhancement. Dischargers must seek to minimize pathogen releases, reduce particulate dispersion, and diminish organics in effluents. These factors impact heavily on the effectiveness of wastewater disinfection. Furthermore, with passage downstream to the water intake, these organic residuals may be the precursors of disinfection by‐products created during drinking water treatment. Some water supply operations must revise their treatment practices to provide better protection from the passage of protozoan cysts and enhance the removal of organics before applying disinfection. Disinfection of water supply is critical and will only be consistently effective in a clean processed water.
Influence of combined chemicals on prodigiosin Synthesis of Serratia marcescens
Authors: Blessing Brigitte , Süssmuth Roland 
Published: October 2006

AbstractThe influences of pesticides (Imugan, Diuron, 2,4‐D. Simazin, Benodanil, E 600, Parathion, Eserin, Aldrin), heavy metals (ZnCl2, CdCl2, CuSO4, HgCl2), and mixtures of these two chemical groups on the rate of prodigiosin synthesized by Serratia marcescens in liquid medium have been studied. Prodigiosin synthesis showed a high sensitivity to toxicants. Therefore, a method is suggested using prodigiosin synthesis of S. marcescens for toxicity testing. The amount of prodigiosin and the inhibition zones in cup plate assays were tested in addition. In mixture, various effects depending on the toxin concentrations, used in the test, could be found: The activation of prodigiosin synthesis in submerged cultures by 0.3 mg Benodanil/L was more than 100% in the presence of Imugan or Diuron, and 256% in the presence of 1.5 mg HgCl2/L.
Assessment of mutagenic activity in drinking water from São Paulo City, Brazil
Authors: Sanchez Petra S. , Coimbrao Carlos A. , Coelho Maria C. L. , Valent Gisela U. , Sato Maria I. Z. , Martins Maria T. 
Published: October 2006

AbstractDuring the last decade, studies carried out in several countries throughout the world have disclosed the presence of halogenated hydrocarbons and other potentially carcinogenic compounds in drinking water, causing public concern with respect to the quality of drinking water. Considering this problem, chlorinated drinking water from seven water treatment plants in São Paulo and from its water sources were tested for mutagenicity in the Ames/Salmonella assay. Different volumes of raw and treated waters were concentrated by XAD‐2 resin, and eluted in methanol and methylene chloride. Organic extracts ressuspended in DMSO were assayed for dose response in Salmonella typhimrium strains TA98 and TA100, with and without metabolic activation, using the plate incorporation technique. Results showed higher incidence of mutagenic activity in water samples after chlorination than in raw water. The majority of positive responses were decreased by addition of metabolic activation, confirming the presence of direct‐acting mutagens, produced during water chlorination, although significant mutagenicity was also observed in the presence of S9. Mutagenic levels ranged from 104 to 569 revertants/L in raw water, and in chlorinated drinking water, between 10 and 418 revertants/L. Based on the results obtained in this study, it is essential to study and identify mutagenic compounds evolving from the chlorination processes, and to determine, for water treatment plants with high incidence of mutagenic compounds, the procedures to avoid or eliminate this problem, as well as to establish an effective monitoring program.
Cadmium as an uncoupler of respiration in Ulva lactuca
Authors: Webster Elizabeth A. , Gadd Geoffrey M. 
Published: October 2006

AbstractThe effect of cadmium on the respiration of Ulva lactuca was examined using an oxygen electrode. Discs of U. lactuca thallus in filtered seawater were either incubated in the dark for 24 h or treated with 20 μM 3(3,4‐dichlorophenyl) 1,1‐dimethylurea to inhibit photosystem II dependent noncyclic electron transfer. In both cases, the addition of cadmium, as sulphate, increased respiration, with maximum stimulation occurring at approximately 15 mM; above this concentration respiration declined and at >21 mM inhibitory effects were significant. Dinitrophenol (DNP, 50 μM) and carbonyl cyanide m‐chlorophenylhydrazone (CCCP, 10 μM) also uncoupled respiration of U. lactuca, and when these compounds were used in conjunction with Cd the effects were found to be additive. Oligomycin (12.5 μ mL−1), which inhibits the mitochondrial ATPase, inhibited U. lactuca respiration but subsequent Cd addition (to 6 mM) resulted in a 2.5 × increase in respiration over control values. DNP had a similar effect when used with oligomycin. DNP and CCCP had a negligible effect on the respiration of KCN‐treated discs but the addition of Cd restored respiration to control values, probably because of the formation of insoluble Cd(CN)2. These results demonstrate that Cd can act as a respiratory uncoupler in U. lactuca.
Seasonal variations of microcystis species and toxic heptapeptide microcystins in lake suwa
Authors: Park Ho‐Dong , Watanabe Mariyo F. , Harada Ken‐Ichi , Suzuki Makoto , Hayashi Hidetake , Okino Tokio 
Published: October 2006

AbstractSeasonal changes in species composition of Microcystis and concentrations of toxic heptapeptide microcystins, were investigated in Lake Suwa from June to October in 1991. Microcystins‐RR and ‐LR were the main components of the toxins contained in bloom samples of Microcystis and a very little quantity of ‐ YR was detected through this period. The high amounts of microcystins were estimated during the exponential growth phase of the bloom from June 11 to July 20. The highest concentrations of microcystins‐RR and ‐LR were estimated as 121 and 81.6 μg/100 mg cells on July 20, 1991, respectively. While the higher amounts of the toxins were estimated when M. aeruginosa predominated, the lower amounts were estimated during the predominate period of M. viridis. Since the dissolved inorganic nitrogen (DIN) concentration may well affect the dominance of M. aeruginosa and M. viridis, the production of the toxins by Microcystis may be associated with the DIN concentration. © 1993 John Wiley & Sons, Inc.
Interactive toxic effect and distribution of heavy metals in phytoplankton
Authors: Okamura Hideo , Aoyama Isao 
Published: October 2006

AbstractAssessing the interactive toxic effect of chemicals in the environment is becoming a matter of increasing public focus on and concern with ecotoxicological aspects. The purpose of this study is to find the relationship between an interactive toxic effect and distribution of heavy metals in algal cells. The green alga Chlorella ellipsoidea Gernec(IAMC‐27) was cultured for 6 days in the presence of cadmium and/or chromium. Algal cells were divided into 4 fractions by centrifugation after the cells were disrupted using a French press. The amounts of the metals in each fraction were determined.The interaction effect between the two metals on algal growth was investigated. The amount of one metal taken up in the cells and the growth inhibition rate increased with the concentration of metals in the medium. The amount of one metal in the cells was increased due to the presence of the other metal. Accordingly, the growth inhibition rate also increased. The amounts of Cd accumulated in the soluble fraction and in the membrane fraction of algal cells were 50 and 20%, respectively, of the total amount in the cells. The presence of Cr changed the Cd concentration in both fractions to 40%. The amount of Cr accumulated in each fraction was almost the same in the absence of Cd. The amount of Cr accumulated in the cell wall fraction rose to 90% after 3 days of exposure and it stayed as high as 50% even at the end of the six‐day study period in the presence of Cd. It was assumed that the presence of one metal influenced the distribution of the other metal in the cells, which resulted in the synergistic toxic effect. © 1994 by John Wiley & Sons, Inc..