bluuebunny/crossref_metadata_2025 huggingface dataset:
Structural effect of galactose residue in synthetic glycoconjugates on interaction with rat hepatocytes
Authors: Yura Hirofumi , Goto Mitsuaki , Okazaki Hidemi , Kobayashi Kazukiyo , Akaike Toshihiro
Published: May 2005

N‐p‐Vinylbenzyl‐O‐β‐D‐galactopyranosyl‐(1,4)‐D‐gluconamide (PVLA) has been used as an asialoglycoprotein model polymer. Rat hepatocytes expressing asialoglycoprotein receptors are capable of binding to hydrophobic plastic dishes coated with PVLA. PVLA, water‐soluble polystyrene derivatives bearing galactose residues preferentially adsorb to plastic plates made of polystyrene rather than those of poly(methyl methacrylate). Hence, we modified chitosan beads with linear chains composed of a long alkyl or phenyl moiety to study the effect of structural variations of adsorbed PVLA, and investigated the extent of hepatocyte attachment to the hydrophobic beads coated with PVLA. The attachment was independent of the amount of immobilized PVLA; rather, it was dependent on the hydrophobicity of the beads with PVLA. To simplify the surface of the hydrophobic beads with PVLA, galactopyranoses were covalently linked to chitosan beads via hydrophobic spacer arms, and hepatocyte attachment was compared among the prepared beads. The beads with spacer arms containing phenylalanine and a phthalic moiety showed increased hepatocyte attachment, which was elicited by galactose residues on the beads. These results suggest that rotational restriction or stiffness and hydrophobicity due to the phenyl moiety are essential to enhance the specificity of terminal galactose in PVLA. This analysis contributes to the design and optimization of an artificial ligand for cellular receptors recognizing surgar moieties. © 1995 John Wiley & Sons, Inc.
Catabolite repression in the gram‐positive bacteria: Generation of negative regulators of transcription
Authors: Stewart George C.
Published: May 2005

Operons subject to catabolite repression (CR) in the gram‐positive bacteria appear to be transcriptionally regulated by negative acting catabolite repressors. Cis elements within the promoter regions of a few CR operons have been identified as the target sequences for these repressors. It has also been proposed that sequences internal to the transcriptional unit may represent targets for recognition of the operons as catabolite repressible. The precise mechanism(s) of regulation have yet to be worked out. © 1993 Wiley‐Liss, Inc.
Eukaryotic‐like protein serine/threonine kinases in Myxococcus xanthus, a developmental bacterium exhibiting social behavior
Authors: Munoz‐Dorado Jose , Inouye Sumiko , Inouye Masayori
Published: May 2005

Myxococcus xanthus, a gram‐negative bacterium exhibits a spectacular life cycle and social behavior. Its developmental cycle and multicellular morphogenesis resemble those of eukaryotic slime molds such as Dictyostelium discoideum. On the basis of this resemblance, we explored the existence of eukaryotic‐like protein serine/threonine kinases which are known to play important roles in signal transduction during development of D. discoideum. It was indeed found that M. xanthus contains a large family of protein serine/threonine kinases related to the eukaryotic enzymes. This is the first unambiguous demonstration of eukaryotic‐like protein serine/threonine kinases in the prokaryotes. © 1993 Wiley‐Liss, Inc.
The phosphorelay signal transduction pathway in the initiation of Bacillus subtilis sporulation
Authors: Hoch James A.
Published: May 2005

The formation of spores in Bacillus subtilis is a developmental process under genetic control. The decision to either divide or sporulate is regulated by the state of phosphorylation of the Spo0A transcription factor. Phosphorylated Spo0A (Spo0A ∼ P) is both a repressor and an activator of transcription depending on the promoter it is affecting. Spo0A ∼ P is the end product of the phosphorelay, a signal transduction system linking environmental information to the activation of sporulation. Activation or deinhibition of two ATP‐dependent kinases, KinA and KinB, to phosphorylate the Spo0F secondary messenger initiates the phosphorelay. Spo0F ∼ P is the substrate for the Spo0B protein, a phosphoprotein phosphotransferase which transfers the phosphate group to Spo0A. The Spo0A ∼ P formed from this pathway orchestrates transcription events during the initial stage of spore development through direct effects on a variety of promoters and through the use of other transcription factors, termed transition state regulators, whose activity it controls. Because commitment to sporulation has serious cellular programming consequences and is not undertaken capriciously, the phosphorelay is subject to a variety of complex controls on the flow of phosphate through its components. © 1993 Wiley‐Liss, Inc.
Signal transduction in chemotaxis mediated by the bacterial phosphotransferase system
Authors: Titgemeyer Friedrich
Published: May 2005

Gram‐negative bacteria are able to respond chemotactically to carbohydrates which are substrates of the bacterial phosphoenolpyruvate:sugar phosphotransferase system (PTS). The mechanism of signal transduction in PTS‐mediated chemotaxis is different from the well‐studied mechanism involving methyl‐accepting chemotaxis proteins (MCPs). In PTS‐mediated chemotaxis, carbohydrate transport is required, and phosphorylation seems to be involved in both excitation and adaptation. In this review the roles of the components of the PTS in chemotactic signal transduction are discussed. © 1993 Wiley‐Liss, Inc.
Okadaic acid as an inducer of the 78‐kDa glucose‐regulated protein in 9L rat brain tumor cells
Authors: Hou Ming‐Chin , Shen Chi‐Hsiu , Lee Wen‐Chuan , Lai Yiu‐Kay
Published: May 2005

Okadaic acid (OA), a potent inhibitor of protein phosphatases 1 and 2A, has been widely used as a tool for unravelling the regulation of cellular metabolic processes involving protein phosphorylation/dephosphorylation. It has recently been found that OA can induce reversible hyperphosphorylation of vimentin and reorganization of intermediate filaments [Lee et al., J. Cell. Biochem. 49: 378–393, 1992]. We report here that OA specifically induced the synthesis of a 78‐kDa protein, which was identified as the 78‐kDa glucose‐regulated protein (GRP78) by two‐dimensional sodium dodecylsulfate‐polyacrylamide gel electrophoresis and peptide mapping. The induction of GRP78 by OA was dose‐dependent and reversible. For 7 h treatments, GRP78 synthesis was initially enhanced under 50 nM OA and became the highest (about 6‐fold) under 200 nM OA. Meanwhile, under 200 nM OA, GRP78 synthesis was initially enhanced after 4 h and reached its maximal level (about 8‐fold) after 15 h of treatment. Subsequently, upon removal of OA, the level of OA‐induced GRP78 was reduced to basal level after 12 h of recovery. Induction of GRP78 synthesis by OA was abolished in cells pretreated with actinomycin D and cycloheximide, indicating that it was regulated at the transcriptional level and its induction required de novo protein synthesis. Furthermore, OA suppressed protein glycosylation, and the result lent support to the hypothesis that suppression of protein glycosylation may correlate with induction of GRP78 synthesis. © 1993 Wiley‐Liss, Inc.
Developing consumer/ survivor/recovering voice and its impact on services and research: Our experience with the SAMHSA Women, Co‐Occurring Disorders and Violence Study
Authors: Mockus Susan , Mars Laura Cinq , Ovard Dorothy Guazzo , Mazelis Ruta , Bjelajac Paula , Grady Janice , LaClair Christine , Livingston Cardenia , Slavin Sharon , Williams Susan , McKinney Jacki
Published: May 2005

Integrating consumer/survivor/recovering (C/S/R) women in the Substance Abuse and Mental Health Services Administration's Women, Co‐Occurring Disorders and Violence Study involved both struggles and growth. The C/S/R women and all of our professional allies, both individually and collectively, greatly enhanced the study by overcoming what earlier seemed to be insurmountable obstacles. Integral to the C/S/R group's personal and professional growth was the development and expression of their individual and collective voices. Documenting this history and the impact that the collaboration between the C/S/R women and other professional staff had on the study is of vital importance in the field of research and advocacy. © 2005 Wiley Periodicals, Inc. J Comm Psychol 33: 513–525, 2005.
High‐pressure liquid‐chromatographic determination of the anthelmintic drug mebendazole in plasma
Authors: Karlaganis G. , Münst G. J. , Bircher J.
Published: May 2005

A procedure for determining the anthelmintic drug mebendazole in plasma of patients is described. Mebendazole together with the internal standard ciclobendazole is extracted with chloroform at pH 11. The extract is analyzed isocratically on a LiChrosorb SI 60 column with a mobile phase consisting of acetonitrile/water‐saturated chloroform/ammonia (75/92.5/0.1) at 307 nm. Reproducibility with a coefficient of variation of 3 to 10% is attainable for the concentration range of 20 to 200 ng mebendazole/ml plasma. Mebendazole plasma concentrations in patients with echinococcosis on chronic therapy with mebendazole ranged from 6 to 117 ng/ml.
Resolution of equine estrogens using glass capillary columns
Authors: Pillai G. K. , McErlane K. M.
Published: May 2005

A rapid and specific procedure is described for the resolution of nine steroids present in conjugated estrogen preparations. Resolution is achieved on a short glass capillary column coated with Silar 10C after dual derivatization to oxime‐trimethylsilyl ethers.
Correlation between excess adsorption data measured for solvent mixture/adsorbent systems and RM values obtained for different solutes chromatographed in binary mobile phases
Authors: Ościk‐Mendyk B. , Róz̈ło J. K. , Jaroniec M.
Published: May 2005

This paper concerns the application of excess adsorption isotherms, measured for solvent mixture/adsorbent systems, to the characterization of TLC data. For this purpose the excess adsorption isotherms for three liquid mixtures: cyclohexane/ benzene, benzene/acetone, and carbon tetrachloride/ethyl acetate on silica gel at 20°C have been measured. These mixtures have been used as binary mobile phases in TLC measurements. It has been shown for a given solute in binary mobile phase that the quantity RM is a simple function of the excess adsorption. Parameters of this function have been used to characterize chromatographic systems with binary mobile phases.
Application of multidimensional switching to the analysis of volatiles
Authors: Sevcik J.
Published: May 2005

A multidimensional switching system with two packed columns has been used for the analysis of volatiles. Use of a high‐boiling solvent and the backflush mode permitted total resolution of the mixture discussed in a short analysis time.
Stimultaneous quantitative analysis using dual capillary columns of different polarities
Authors: Wright C. W.
Published: May 2005

Complex organic mixtures, such as coal liquefaction and oil shale products and by‐products, are comprised of hundreds or thousands of individual components. State‐of‐the‐art high resolution gas chromatography does not always provide sufficient resolution to allow accurate quantitation or identification of many compounds of interest. The concept of dual capillary column chromatography combines the different resolving characteristics of two capillary columns coated with different stationary phases into a single chromatographic run. In this approach, both columns are connected to the same injection port. Analysis of complex mixtures in this fashion can confirm the identification and quantitation of components on two columns of different polarity with little increased analysis time, can provide a means of obtaining quantitative data for individual components which are known to coelute on any one column, and can alert one to unknown coelution problems that would be undetected by gas chromatographic analysis on a single capillary column.

Simultaneous dual column analysis was applied to three samples, the neutral polycyclic aromatic hydrocarbon (PAH) fraction of a Solvent Refined Coal‐II (SRC‐II) heavy distillate, the nitrogen‐containing polycyclic aromatic compound (N‐PAC) fraction of an SRC‐II heavy distillate, and the basic fraction from a shale oil process water. Fused silica capillary columns coated with SE‐54 and Durawax 3 were used for the analyses of the heavy distillate, while SE‐54 an Carbowax 20M capillary columns were used for the analysis of the process water.
Isomer‐specific separation and quantitation of tetrachlorodibenzo‐p‐dioxins by HRGC and HRGC/MS
Authors: Onuska F. I. , Wilkinson R. J. , Terry K.
Published: May 2005

A method is described for the determination of 22 tetrachlorodibenzo‐p‐dioxin isomers at the low part‐per‐trillion (ppt) level. High resolution, narrow bore, open tubular columns (OTCs) with 100 μm i.d. can achieve better separations than presently used 320 or 250 μm i.d. columns in about half the total time. Relative retention times and response factors for all 22 TCDD isomers are presented for the electron capture detection and for the molecular ion mass of individual isomers under electron impact ionization with selected ion monitoring (SIM).
Reproducibility in capillary supercritical fluid chromatography: Comparison of injection techniques
Authors: Richter B. E. , Knowles D. E. , Andersen M. R. , Porter N. L. , Campbell E. R. , Later D. W.
Published: May 2005

An analysis of the precision obtained using commercially available microvalve injectors is reported for three modes of injection: conventional split; timed‐split; and direct. Results from this study show that good precision (< 3% RSD for external standard and < 1% RSD for internal standard methods) can be obtained with capillary supercritical fluid chromatography (SFC). However, particular attention must be paid to the type of valve used, the orientation of the column relative to the valve, the mode of interfacing or connecting the column to the valve, and the type of pressure or density programming used for the analysis as all of these factors will affect the reproducibility.
Capillary and packed column SFC/MS
Authors: Berry A. J. , Games D. E. , Mylchreest I. C. , Perkins J. R. , Pleasance S.
Published: May 2005

A frit restrictor interface for capillary column supercritical fluid chromatography/mass spectrometry (SFC/MS) has been constructed and used for the analysis of high boiling point alkanes. Packed column SFC/MS is described using both a moving belt liquid chromatographic/mass spectrometric interface and a thermospray source in the filament‐on mode.
Use of small diameter WCOT columns for ultra‐high resolution GC/MS
Authors: Hyver K. J.
Published: May 2005

For clinical and environmental analyses utilizing capillary gas chromatography/mass spectrometry (GC/MS), increased sensitivity and speed of analysis are highly desirable. These performance advantages are realized using a WCOT column of 100 μm i.d. as compared to the more conventional 200 μm i.d. capillary columns. The improved sensitivity of capillary direct GC/MS with the 100 μm i.d. column for the confirmation of drugs of abuse will be demonstrated. For environmental analysis, the superior efficiency and resolution of the 100 μm i.d. column can be employed for the separation of priority pollutants. This approach is more amenable to capillary direct GC/MS providing a more effective interface to the mass spectrometer. As a result improved sensitivity and a considerable decrease in analysis time is achieved over that obtained with the larger diameter environmental specialty phase columns.
Determination of soil fumigants in air using tandem capillary gas chromatography after charcoal trapping
Authors: Tuinstra L. G. M. Th. , Traag W. A. , Roos A. H.
Published: May 2005

Soil fumigants, like 1,3‐dichloropropene and metham‐sodium (forming methyl isothiocyanate) diffuse into the atmosphere, thus presenting a hazard to people in the surroundings. A method is described in which a large volume (50 μl) of extractant, used to desorb the compounds from charcoal, is injected into a GC, equipped with two capillary columns. By way of Deans switching, the solvent is separated from the compounds of interest. Modification of a GC sampler makes unattended analyses possible.
Computer‐controlled vacuum backflush for capillary GC
Authors: Rankin Christine , Sacks Richard
Published: May 2005

A vacuum‐pump‐operated backflush system has been developed for applications involving high‐speed, repetitive GC analysis of gas streams containing ppm and ppb levels of organic vapor. The system uses an injector capable of cryofocusing and a relatively short length of 0.25‐mm i.d. fused silica column for the separation of relatively simple mixtures of volatile compounds. Analysis times typically are in the 5–10 s range, and backflush times are in the 2–5 s range. Gases from the flame ionization detector are used as the backflush carrier gas, and no modification of the detector is necessary. A procedure is described which allows the average gas velocity to be measured during backflush operation. The minimum backflush time is directly proportional to the analysis time and to the square of the column length, making this system most useful with short columns and short analysis times.
On‐line solvent evaporator for coupled LC systems
Authors: Grob Konrad , Tönz Barbara
Published: May 2005

The mobile phase of a fraction eluted from a first LC column is removed by an on‐line evaporator in order to reconcentrate the solute material or to exchange the eluent before performing a subsequent LC separation. Evaporation essentially occurs by concurrent evaporation, i.e. the solvent evaporates at a rate equal to the flow rate of the incoming eluent, and is driven by the overflow principle, i.e. vapors leave the tube as a result of the expansion resulting from evaporation.

The liquid is introduced into a small tube (e.g., 4 cm × 1.3 mm i.d.) which is packed, e.g., with a coarse silica gel. The outlet of the evaporator is connected to vacuum in order to enable evaporation at reduced temperature and to increase retention of the volatile components. With normal phase eluents, evaporation rates may approach 1 ml/min; n‐dodecane was the most volatile n‐alkane fully retained by the evaporator.
Improved method for the determination of sulfur components in natural gas
Authors: Tuan Hai Pham , Janssen Hans‐Gerd , Kuiper‐van Loo Ellen M. , Vlap Harm
Published: May 2005

Determination of trace concentrations of sulfur components in natural gas is a true analytical challenge. Only analytical procedures based on gas chromatography can meet the sensitivity and accuracy requirements dictated by environmental regulation institutions and modern chemical industry. In the present contribution the sample pretreatment and chromatographic separation steps have been evaluated and optimized based on the use of a flamebased sulfur chemiluminescence detector (SCD) for target compound detection.

The proposed instrument consists of a programmed temperature vaporizing (PTV) injector employing a liner packed with Chromosorb 104, a 4 μm thick film apolar column and a flame‐based SCD. Using a 13 mL sample loop the detection limit achievable with the new method is 3 μg S/m3. The precision of replicate measure. ments is generally in the range of 5–15% relative standard deviation. Lower detection limits can be achieved by preconcentrating larger sample volumes, e.g. 100 mL.
Optimization of selectivity in capillary zone electrophoresis and micellar electrokinetic capillary chromatography using the iterative regression strategy
Authors: Corstjens Hugo , Oord André E. E. , Billiet Hugo A. H. , Frank Johannes , Luyben Karel Ch. A. M.
Published: May 2005

An iterative regression design has been used in the optimization of selectivity in capillary zone electrophoresis and micellar electrokinetic capillary chromatography. This strategy, initially developed for HPLC, is modified in respect of the choice of the parameter(s) and the parameter space and the description of the migration behavior of (charged) solutes in capillary electrophoresis. The six test solutes could not be fully resolved by adjusting the pH in a free zone system but the simultaneous two‐parameter optimization of the pH and the concentration of surfactant resulted in baseline separation of all the solutes. Further improvement may be obtained when distorted peak shapes are also considered at the level of the parameter choice and the criterion.
Microextraction by demixing of two miscible solvents for the determination of phenols in water
Authors: Onuska Francis I. , Terry K. A.
Published: May 2005

A method for the determination of anionic solutes such as phenol, cresols, and xylenols present in industrial effluents has been developed. It is based on microextraction using two miscible phases followed by demixing of the phases by the addition of ammonium sulfate. The extraction properties of 2‐propanol were examined and the procedures were optimized. High resolution gas chromatography–mass spectrometry in the selected ion monitoring mode was used as a separation and quantitation technique. This method is rapid and precise and allows detection limits of 1 μg L−1 to be easily obtainable employing a 50 mL water sample.
Correlation between structure of dihydropyridine calcium antagonists and their retention behavior and enantioseparation on the β‐cyclodextrin stationary phase in HPLC
Authors: Tesarová E. , Gilar M. , Hobza P. , Kabelác M. , Deyl Z. , Smolková‐Keulemansová E.
Published: May 2005

Chromatographic data for five dihydropyridine calcium antagonists (CAs) were obtained on β‐cyclodextrin column in the reversed phase HPLC. Interaction energies of solute‐cyclodextrin complexes formed by docking of different parts of the CAs' molecules into the cyclodextrin cavity were calculated. Results from the HPLC experiments and molecular modeling were compared. It was found that several types of inclusion complexes are energetically possible and contribute to the retention simultaneously. Only certain inclusion complex are assumed to be responsible for enantioseparation of CAs. Nevertheless molecular modeling studies are a useful tool for explaining the enantioselectivity and predicting the elution order of enantiomers.
Molecular recognition and self‐replication
Authors: Rebek Julius
Published: May 2005

Self‐replicating molecules stand at the very boundary of chemistry with biology. This review describes the development of synthetic structures capable of self‐replication from studies in molecular recognition. The weak intermolecular forces—hydrogen bonds and aromatic stacking interactions—that characterize interactions of nucleic acid components were designed into synthetic receptors for adenine. Covalent conjugates of these receptors with adenines gave self‐complementary structures capable of replication. The new systems feature autocatalysis, sigmoidal product growth and even mutation. General rules for the design of replicating systems are described and these suggest that the evolution of replicating molecules was an inevitable event.
Intermolecular interactions in type I collagens
Authors: David Carl W.
Published: May 2005

X‐PLOR modelling of collagen dimers containing Gly‐Glu‐Arg in each chain has been carried out. The interaction between molecules when two Gly_Glu‐Arg are present on each chain is found to be substantially less than two times that obtained with one per chain, implying that relative tilting of two collagen molecules does not offset the disadvantages of misalignment of the interacting moieties. This implies that if multiple (Glu−‐Arg+)3 interactions are important in fibril formation, their lateral separations must be large enough to insure that they act independently.
Vibrational spectra of substituted platinum(IV) ammine complexes. I: [Pt (NH3)6]4+; [Pt (NH3)5X]3+, X = Cl, Br; mer [Pt (NH3)3Cl3]+and [Pt(NH3)Cl5]−
Authors: Nolan M. J. , James David W.
Published: May 2005

The Raman and infrared spectra (4000–40 cm−1) have been recorded for the salts [Pt (NH3)6]Cl4, [Pt (NH3)5X]X3 (X = Cl, Br), mer [Pt (NH3)3Cl3]Cl and K [Pt (NH3)Cl5], in the solid state. The results are primarily explicable on a point group model for the complex ion. For the monohalo and pentahalo derivatives solution Raman spectra were recorded. These indicated that solid state effects are more pronounced for the monohalo derivatives.
Vibrational spectra of substituted platinum(IV) ammine complexes. II: cis and trans isomers of [Pt (NH3)4X2]2+and [Pt (NH3)2x4] where X = Cl, Br and I
Authors: James David W. , Nolan M. J.
Published: May 2005

The Raman and infrared spectra (4000–40 cm−1) have been obtained for many compounds of the series [Pt(NH3)4X2]2+ and [Pt (NH3)2X4] (cis and trans isomers) where X = Cl, Br, I. The spectra have been interpreted using the point‐group and factor‐group approaches.
Raman spectra and phase transition of ammonium paraperiodate (NH4)2 H3IO6
Authors: Poulet H. , Mathieu J. P.
Published: May 2005

Polarized Raman spectra of single crystals of (NH4)2IO6 are recorded at 270 K and 24 K and analyzed. The failure of the selection rules does not allow a choice between the two structures proposed for the low temperature phase.
Raman spectra and crystal structures of methyl halides
Authors: Takeuchi H. , Bribes J.‐L. , Harada I. , Shimanouchi T.
Published: May 2005

The Raman spectra of crystalline methyl halides and the deuterated analogues were investigated at liquid nitrogen temperature. The weak band newly observed at 156 cm−1 in the spectrum of CH3Cl has been assigned to the rotational lattice mode about the molecular symmetry axis. Three translational lattice vibrations were also found at 84, 71, and 60 cm−1 for CH3Cl (83, 68, and 59 cm−1 for CD3Cl). Of the seven and six lattice vibrations of methyl bromide and methyl iodide, respectively, two higher frequency bands were assigned to the rotational modes and the rest were assigned to the translational modes. The present experimental results are interpreted in terms of the crystal structures, C2ν for methyl chloride and D2h for methyl bromide and methyl iodide.
A Raman spectroscopic investigation of the conformation of the cyclohexyl halides C6H11X (X = Cl, Br and I) in thiourea clathrates
Authors: Allen A. , Fawcett V. , Long D. A.
Published: May 2005

The Raman spectra of the cyclohexyl halide‐thiourea clathrates have been investigated. It is found that whereas cyclohexyl chloride and bromide exist only in the axial conformation in the clathrate, cyclohexyl iodide exists in both the axial and equatorial conformations in the clathrate.
Raman and IR spectra of matrix isolated OsO3F2 AND OsO4: The molecular shape of monomeric OsO3F2
Authors: Beattle I. R. , Blayden H. E. , Crocombe R. A. , Jones P. J. , Ogden J. S.
Published: May 2005

This paper reports fundamental vibration frequencies for molecular OsO3F2 and OsO4 isolated in argon matrices at low temperatures. OsO3F2 is shown to have D3h symmetry on the basis of Raman and IR selection rules, and this conclusion is confirmed by the results of 18O enrichment studies which demonstrate the presence of an OsO3 unit containing three equivalent oxygens. The argon matrix frequencies are 946.5 (A′1), 928.5 (E′), 646 (A′2), 619 (A′/1) 348 (E″), 316.5 (E′) 258 (A″2) and 206 (E′) cm−1. High resolution spectra are also reported for matrix isolated Os16O4 (ν1 963, ν2 332, ν3 956, and ν4 327 cm−1) and for 18O enriched OsO4 species.
Liaison hydrogène en phase liquide et spectrométrie Raman. IV—structure des polymères du méthanol liquide pur et dissous en solvants inertes
Authors: Maillard D. , Perchard C. , Perchard J. P.
Published: May 2005

Calculations of νOH vibrational frequencies and of the corresponding IR and Raman intensities have been carried out according to two models of polymerization of alcohols (chains and cycles). They are compared to experimental spectra of methanol (pure liquid and solutions in CCl4) and of isopropanol dissolved in freons at low temperature. For methanol at 295 K, the best fit is obtained for a cyclic structure of polymers, with an average degree of polymerization of 5–6; for isopropanol at 106 K cyclic tetramers are preponderant.
Polarized Raman spectra and intermolecular potential of DL‐alanine crystal
Authors: Machida Katsunosuke , Kagayama Akira , Saito Yutaka
Published: May 2005

Polarized Raman spectra of DL‐alanine and N‐deuterated DL‐alanine single crystals have been recorded. A normal coordinate analysis has been made for the optical active intra‐ and intermolecular vibrations of DL‐alanine crystal. As in the case of L‐alanine crystal, large factor group splittings were observed for the CH3 asymmetric deformation mode. The magnitudes of the observed splittings are elucidated well by the empirical potential function of the exp‐6 type for the non‐bonded atom‐atom interaction. The differences in the NH3 rocking and the CH3 rocking frequencies between L‐ and DL‐alanine crystals are ascribed to the differences in the intermolecular potential and the molecular geometry, respectively. A good agreement was obtained between the observed and the calculated lattice frequencies.
Raman investigation of palladium oxide, rhodium sesquioxide and palladium rhodium dioxide
Authors: Weber W. H. , Baird R. J. , Graham G. W.
Published: May 2005

Raman spectra were obtained from PdO, Rh2O3 and PdRhO2 thin films formed by oxidizing foil samples. Polarization measurements allow symmetry species assignments to be made for the lines from the corundum phase of Rh2O3 and from PdRhO2, which has a delafossite structure.
Perturbation theoretical study of resonance Raman intensities: Contribution of forbidden electronic states
Authors: Okamoto Hiromi
Published: May 2005

An equation which describes vibrational resonance Raman intensities was derived using the non‐adiabatically expanded (to the second order) state vector and the damped Kramers‐Heisenberg‐Dirac dispersion equation. The equation obtained includes the terms which correspond to the equation previously proposed by Albrecht, by Zgierski and by Korenowski et al. Forbidden electronic states may contribute to Raman intensities through the second‐order terms. The Raman excitation profile is predicted to show a characteristic pattern for a system where one of these second‐order terms plays an important role. The physical meanings of these higher order terms are discussed.
Surface‐enhanced Raman scattering of nucleic acid components in silver sol: Uracil and its derivatives
Authors: Oh Weon Sik , Suh Se Won , Kim Myung Soo
Published: May 2005

The surface‐enhanced Raman scattering (SERS) of uracil, uridine, 2′‐deoxyuridine and 5′‐rUMP adsorbed on aqueous silver sol was investigated. Uracil was found to adsorb as the N‐3 deprotonated form, which underwent a reorientation from the situation where the base was perpendicular to the surface to the situation where the base lay flat on the surface as the surface charge was made more negative. The N‐3 deprotonated molecules of uridine, 2′‐deoxyuridine and 5′‐rUMP were found to lie flat on the silver surface regardless of the bulk concentration and the silver surface charge.
Vibrational dephasing in liquid germane
Authors: Wilde Richard E.
Published: May 2005

Raman spectra are reported for the n̈1 bands of germane and germane‐d3. Fourier transformation of the band shapes provided vibrational autocorrelation functions. These functions were modeled by a memory‐function procedure. Evidence for resonant vibrational energy transfer and higher order cumulant‐expansion terms was found in an isotopic‐dilution study.
Raman study of the effect of LiCl and CsCl on the resonance intermolecular coupling and the Fermi resonance of water
Authors: Sokołowska Anna
Published: May 2005

Changes in the isotropic and anisotropic component contours of the H2O and D2 stretching bands in aqueous solutions of LiCl and CsCl were studied within the entire accessible concentration range. The isotropic component contours were resolved into three constituents and the anisotropic contours into four. The resonance intermolecular coupling constants, V1 for the ν1 vibration and V2 for the 2ν2 overtone, and the Fermi resonance constant, W, of water were determined for solutions of various electrolyte concentrations. The added electrolytes were found to lower the V1 and V2 values. The Fermi resonance coupling constant decreased in aqueous LiCl solutions and was constant in CsCl solutions. The unperturbed ν1 and 2ν2 band positions of the LiCl solutions did not change. In the CsCl solutions, ν1 shifted to lower frequencies and 2ν2 to higher frequencies. A new component was found to appear in the anisotropic component for concentrated LiCl solutions, at 3550 cm−1 for H2O and 2590 cm−1 for D2O.
Raman–Rayleigh scattering measurements in reacting and non‐reacting dilute two‐phase flows
Authors: Masri A. R. , Dibble R. W. , Barlow R. S.
Published: May 2005

Simultaneous space‐ and time‐resolved measurements of scalars were made in reacting and non‐reacting dilute, two‐phase, jet flows of methanol. The spontaneous Raman–Rayleigh scattering technique was used to measure temperature and the concentrations of CH3OH, O2, N2, H2, H2O, CO and CO2. In the reacting case, laserinduced fluorescence from the hydroxyl radical was jointly measured. The two‐phase flow is formed at atmospheric pressure at the exit of an axisymmetric jet centered in a co‐flowing stream of air. At the measurement location of ten fuel jet diameters downstream of the nozzle exit plane the volume percentage of liquid in the center of the jet is estimated at about 0.015%. The Rayleigh‐scattered signal can only be used as a marker for the existence of liquid in the measurement volume as it is overhwlemed by Mie and possibly geometrical scattering from droplets. The methanol Raman signal from the liquid–gas mixture increases, mainly owing to the increase in the number density of molecules and the local field effect. Raman signals from other gaseous species are not affected by the existence of droplets in the measurement volume. Gas‐phase temperature is obtained from the sum of the species number densities. The fluorescence from OH shows occasional unrealistic overshoots for rich mixtures, which indicates some interference due to the existence of droplets.
The quaternary structure of Alfalfa mosaic virus
Authors: Mellema Jan E. , van Den Berg Hans J. N.
Published: May 2005

From an analysis of electron micrographs of Alfalfa Mosaic Virus (AMV), evidence has been obtained which favors a cylindrical P6 lattice for the protein coat of the virus. For the analysis use was made of optical diffraction and computer processing of electron images of negatively stained virus particles.

The virus coat exhibits polymorphism. Two kinds of structure were found: a stacked and a helical type. In the stacked type of lattice the unit cells are arranged in staggered rings in such a way that two rings comprise a repeat distance of the structure. The selection rule for the optical diffraction patterns of the stacked form is 1 = n + 2m, in which n is an integer multiple of 3. The layerlines are equally spaced at a distance of approximately 1/80 Å−1.

In the helical type of lattice these rings of unit cells are transformed into turns of a double helix. The selection rule derived in this case is 1 = 6n − 17m, in which n is an integer multiple of 2. The repeat of the structure is approximately 440 Å.
Effects of sodium ions on the electrical and pH gradients across the membrane of streptococcus lactis cells
Authors: Barker Susan L. , Kashket Eva R.
Published: May 2005

Energized cells of Streptococcus lactis conserve and transduce energy at the plasma membrane in the form of an electrochemical gradient of hydrogen ions (Δp). An increase in energy‐consuming processes, such as cation transport, would be expected to result in a change in the steady state Δp. We determined the electrical gradient (ΔΨ) from the fluorescence of a membrane potential‐sensitive cyanine dye, and the chemical H+gradient (ΔpH) from the distribution of a weak acid. In glycolyzing cells incubated at pH 5 the addition of NaCl to 200 mM partially dissipated the Δp by decreasing ΔΨ, while the ΔpH was constant. The Δp was also determined independently from the accumulation levels of thiomethyl‐β‐galactoside. The Δp values decreased in cell fermenting glucose at pH 5 or pH 7 when NaCl was added, while the ΔpH values were unaffected; cells fermenting arginine at pH 7 showed similar effects. Thus, these nongrowing cells cannot fully compensate for the energy demand of cation transport.
Effect of phospholipase A2 on purified gastric vesicles
Authors: Saccomani Gaetano , Chang Hsuan H. , Spisni Alberto , Helander Herbert F. , Spitzer Hugh L. , Sachs George
Published: May 2005

The phospholipid and fatty acid composition and role of phospholipids in enzyme and transport function of gastric (H++K+)‐ATPase vesicles was studied using phospholipase A2 (bee venom). The composition (%) was phosphatidylcholine (PC) 33%; sphingomyelin (sph) 25%; phosphatidylethanolamine (PE) 22%; phosphatidylserine (PS) 11%; and phosphatidylinositol (PI) 8%. The fatty acid composition showed a high degree of unsaturation. In both fresh and lyophilized preparations, even with prolonged incubation, only 50% of phospholipids were hydrolyzed, but the amount of PE and PS disappearing was increased following lyophilization. There was a marked decrease in K+‐ATPase activity (75%) but essentially no loss of the associated K+ p‐nitrophenyl phosphatase was found. ATPase activity could be largely restored by various phospholipids (PE > PC > PS). There was also an increase in Mg2+‐ATPase activity, partially reversed in fresh preparations by the addition of phospholipids (PE > PS > PC). Proton transport activity of the preparation was rapidly inhibited, initially due to a large increase in the HC1 permeability of the preparation. Associated with these enzymatic and functional changes, the ATP‐induced conformational changes, as indicated by circular dichroism spectra were inhibited.
Human placental cell surface antigens: Expression by cultured cells of diverse phenotypic origin
Authors: Hamilton Thomas A. , Wada H. Garrett , Sussman Howard H.
Published: May 2005

The present work examined the expression of cell surface glycoprotein antigens in cultured human cell lines. The set of glycoproteins studied was defined by their immunoreactivity with antiserum developed to Triton‐solubilized extracts of placental brush border membranes. Studies were performed using cell lines of trophoblastic (BeWo, JEG‐3) and nontrophoblastic (Chang liver cells) origin, as well as diploid fibroblast cell lines (WI‐38, GM‐38).

Antiplacental brush border antiserum reacts with at least 19 distinct antigens present in placental membrane preparations, each of which can be resolved and identified in two‐dimensional electrophoresis. The subunit molecular weight and isoelectric point for all components were defined by their positions in the two‐dimensional matrix. Thirteen of these could be detected among the five cell lines examined by lactoperoxidase‐catalyzed cell surface iodination.

One of these 13 antigens has been identified as the placental isoenzyme of alkaline phosphatase (PAP). The expression of this component is limited to choriocarcinonia cells and Chang liver cells and it is not present in diploid fibroblasts. Under normal circumstances expression of PAP is unique to the differentiated placenta but has been frequently demonstrated in both trophoblastic and nontrophoblastic neoplasms.

Two other antigens are variably expressed among the different cell types examined in the present study and their presence or absence was independent of the trophoblastic, epithelial nontrophoblastic, or fibroblastic origin of the cells.

Ten surface antigens were expressed in all five cell lines. Six of these had previously been found common to membranes from three adult differentiated tissues, including liver and kidney, as well as placenta (Wada et al, J Supramol Struc 10(3):287–305, 1979). The presence of this set of antigens in cultured cells as well extends the possibility that these are ubiquitously expressed on human cell surfaces. Two other antigens observed in all cultured cells had been found in both placental and either kidney or liver membranes and may represent common functions shared by many tissues which are also necessary for growth in vitro. The two remaining placental antigens seen in all cultured cells have previously been shown to be absent in adult tissues. Their presence in cultured cells but not in the membranes of resting differentiated tissues may signify the expression of glycoproteins characteristic of trophoblasts in all cells adapted to growth in culture.
Selective protein transport: Identity of the solubilized phosvitin receptor from chicken oocytes
Authors: Woods John W. , Roth Thomas F.
Published: May 2005

By two independent methods, the solubilized receptor for phosvitin (PV) has a subunit MW of 116K. Affinity chromatography, showed that only 2 of the more than 25 proteins present in the total detergent solubilized oocyte membrane extract were retained on a PV–agarose column. These proteins of MW of 116K and 100K could be eluted from PV–agarose with free PV. By gel exclusion chromatography, the receptor‐125I‐PV complexes elute in the void volume of a Biogel A‐1.5 column. When these void fractions were assayed by SDS‐PAGE only a single protein of MW of 116K was observed in addition to 125I‐PV.
Alterations in the responsiveness of diabetic fibroblasts to insulin
Authors: Raizada Mohan K. , Fellows Robert E.
Published: May 2005

Fibroblastic cultures from the skin of nondiabetic and diabetic (db/db) mice have been used to investigate alterations in the biological responses of diabetic cells to insulin. Confluent cultures from the skin of both nondiabetic and diabetic animals possess specific receptors for insulin. Diabetic fibroblasts exhibit only 36% as much specific binding of insulin as nondiabetic fibroblasts, because of a decrease in the total number of binding sites, without a change in binding affinity. Insulin caused a time‐ and dose‐dependent increase in the rate of 2‐deoxy D‐glucose (dGlc) uptake and in ornithine decarboxylase (ODC) activity of both nondiabetic and diabetic fibroblasts. In nondiabetic cells, half‐maximal increase in dGlc uptake was obtained with 0.3 nM insulin, and a maximum increase of 120% was obtained with 4.1 nM insulin. In contrast, diabetic cultures required 0.8 nM insulin for a half‐maximal increase in dGlc uptake, and maximum stimulation with 4.1 nM insulin was only 50% above control levels. With 4‐fold higher insulin concentrations, ODC activity of diabetic cells was only 40% that of nondiabetic cells. In nondiabetic cells, down regulation of insulin receptors by insulin abolished the ability of insulin to stimulate dGlc uptake. These results demonstrate that cells cultured from diabetic animals, which possess a decreased number of insulin receptors, also exhibit decreased stimulation of deoxy D‐glucose uptake and ornithin decarboxylase activity by insulin.
Properties of receptors for epidermal growth factor in detergent solution: Evidence for heterogeneous aggregated states
Authors: Linsley Peter S. , Fox C. Fred
Published: May 2005

Between 60% and 100% of epidermal growth factor (EGF) binding activity was recovered from membranes of the A431 human epidermoid carcinoma cell line treated with solutions containing the nonionic detergent Triton X‐100. Approximately half of the recovered binding activity was sedimented at low centrifugal forece and hence was operationally insoluble in nonionic detergent solution. Receptors in both the detergent‐soluble and ‐insoluble fractions displayed similar affinities for 125I‐EGF, and the values were in good agreement with those obtained for receptors in untreated membranes. The receptors in both fractions also formed identical direct linkage complexes with 125I‐EGF in similar yield, providing no evidence for partitioning of different molecular species of EGF receptors in the detergent‐soluble and ‐insoluble fractions.

Gel chromatography of the detergent‐soluble membrane fraction on Sepharose 6‐B revealed heterogeneity of 125I‐EGF binding activity; the smallest and most monodisperse peak of activity resolved by this technique was eluted at a Stokes radius of 95 Å. Operationally soluble 125I‐EGF binding activity also behaved heterogeneously during velocity sedimentation; more than half the activity sedimented more rapidly than the apparently monidisperse, 7S form. An average of less than half the nonionic detergent‐solubilized activity recovered from 10 independent membrane preparations behaved as an apparently monodisperse entity. Since a maximum of 60% of 125I‐EGF binding activity was operationally soluble, less than 25% of the total EGF binding activity was recovered in an apparently monodisperse form. The remaining 75% of the EGF receptors displayed a marked tendency to exist as aggregates in nonionic detergent solutions.
Involvement of fibronectin, Von Willebrand factor, and fibrinogen in platelet interaction with solid substrata
Authors: Lahav Judith , Hynes Richard O.
Published: May 2005

The proteins fibronectin (FN), Von Willebrand factor (VWF), and fibrinogen are believed to play a role in platelet function. They arc distributed between the plasma and the platelet pool in the resting state and undergo redistribution upon platelet activation. We have studied their expression on the surface of the platelet and their mobilization following platelet binding to substrata. For the purpose of studying protein expression on the surface of intact platelets either adherent to a substratum or in suspension, the enzyme‐linked immunosorbent assay (ELISA) was elaborated and modified. Using this technique as well as immunofluorescence, we found that antiserum raised against carefully washed human platelets recognized FN, VWF, and fibrinogen as well as platelet surfaces. However, specific antisera against these three proteins failed to bind to the surface of unactivated gel‐filtered platelets. When gel‐filtered platelets were exposed to plastic or fibrillar collagen, they adhered and spread. Such platelets did bind antibodies against FN, VWF, and fibrinogen, Moreover, when the adherent platelets were incubated with FN or with VWF in the absence of ristocetin, they bound these proteins in a concentration‐dependent fashion. The patterns of the bound proteins were not similar, suggesting a different spatial distribution of binding sites. These findings indicate that platelet activation by adhesion to substrata mobilize both endogenous and exogenous pools of these proteins, thereby making them surface associated and probable participants in further binding properties of the activated platelet.
Rejoining of DNA double‐strand breaks in human fibroblasts and its impairment in one ataxia telangiectasia and two fanconi strains
Authors: Coquerelle Thérèse M. , Weibezahn Karl F.
Published: May 2005

Using the technique of neutral elution through polycarbonate filters as a measure of DNA length, and hence of the number of double‐strand breaks incurred as a result of radiation damage, we found that normal human fibroblasts rejoin 50% of all breaks within only 3 min (37°C). This fast rejoining was impaired in fibroblasts from one patient with Ataxia telangiectasia and in fibroblasts from two patients with Fanconi's anemia. Also the number of residual breaks after several hours of repair was higher than in control cells. Other cases with the same diseases were normal in their rejoining of double‐strand breaks.
Spannungsreihe der Metalle im praktischen Korrosionsmittel
Authors: Elze J.
Published: May 2005

Da die bekannte Spannungsreihe der Elemente nur in beschränktem Umfang Aussagen über die Korrosion der Metalle zuläßt, wurden für Wasser und Meerwasser „praktische”︁ Spannungsreihen durch Messungen ermittelt. Es zeigt sich jedoch, daß die Differenz der Spannungsreihenwerte nicht allein für das Korrosionsverhalten von Metallkombinationen maßgebend ist. Es ist auch wichtig, die Steilheit der Strom‐Spannungs‐Funktion der Elektrode im Korrosionsmittel zu kennen.