bluuebunny/crossref_metadata_2025_split huggingface dataset:
Murine teratocarcinoma: A model for virus‐cell interaction in a differentiating cell system
Authors: Friedrich Thomas D. , Lehman John M. 
Published: May 2005

AbstractThe stem cell of the murine teratocarcinoma is refractory to infection with Simian virus 40 and polyoma. Utilizing various procedures, we attempted to alter this block to infection by modifying the infection procedure. Multiple infections with high‐titer SV40 and pretreatment of cells with DEAE‐dextran or the carcinogen 4‐nitroquinoline l‐oxide did not induce embryonal carcinoma cells to produce T‐ antigen. Co‐infection with adenovirus 5, which infects the embryonal carcinoma, and SV40 did not induce the expression of SV40 Tantigen. Therefore, these procedures did not overcome the block to virus infection. The assay for the SV40 T antigen was immunofluorescence; however, the immunoprecipitation technique did not detect T antigen in the infected embryonal carcinoma cells. Finally, the viral DNA present in the embryonal carcinoma was examined for its ability to replicate. These studies showed that viral DNA was not replicating as assayed by the viral DNA's sensitivity to UV irradiation when replicating in the presence of 5‐bromodeoxyundine.
The repair of DNA damage: Recent developments and new insights
Authors: Friedberg E.C. , Bonura T. , Love J.D. , McMillan S. , Radany E.H. , Schultz R.A. 
Published: May 2005

AbstractThis brief review presents the salient features of new developments in the enzymatic repair of base damage to DNA. DNA glycosylases and apurinic/ apyrimidinic (AP) endonucleases are reviewed and evidence is presented that in at least two prokaryote systems incision of UV‐irradiated DNA occurs by the sequential action of these two classes of enzymes. In contradistinction, the uvrA, uvrB, and uvrC gene products of E coli appear to function as a multiprotein complex that catalyzes hydrolysis of phosphodiester bonds in damaged DNA directly. The inducible rapid repair of O6‐ methylguanine in E coli is also reviewed.
The contribution of the calcium‐dependent interaction of aggregation factor molecules to recognition: A system providing additional specificity forces?
Authors: Burkart W. , Burger M.M. 
Published: May 2005

AbstractCells from the sponge Microciona prolifera display on their surfaces large but defined proteoglycan complexes (Microciona aggregation factor = MAF) that mediate species‐specific cell aggregation by a process requiring high calcium ion concentrations. An analysis of MAF‐MAF interactions based on binding studies of MAF to glutaraldehyde‐fixed sponge cells and MAF‐derivatized beads demonstrates that the requirement for high calcium concentrations can be overcome by extremely small amounts of certain polycations such as polybrene, polylysine, or histones. For measurements of the affinity of these substances to MAF, a method was adopted that partitions 125I‐labeled MAF between dextran and polyethyleneglycol in an aqueous two‐phase polymer system depending on the net charge of the complex formed.Since only polymers of positive charges affect binding and partitioning at low concentrations, large areas of interaction similar to those found in glycosaminoglycans are proposed for MAF. Through a multitude of appropriately spaced interaction sites, the rather weak selectivity of single charged sites could in such a system still provide strong enough specificities to explain species‐specific cell sorting.The biological significance of naturally occurring polycations as well as extracellular calcium includes their role in cell recognition, sorting out as well as the ordered and continual streaming movements of groups of cells seen in the mesohyl of live sponges.
The transforming sequences of avian myelocytomatosis virus (MC29)
Authors: Lautenberger James A. , Schulz Robert A. , Garon Claude F. , Tsichlis Philip N. , Spyropoulos Demetri D. , Pry Thomas W. , Rushlow Keith E. , Papas Takis S. 
Published: May 2005

AbstractAvian myelocytomatosis virus (MC29), a defective acute leukemia virus, has a broad oncogenic spectrum in vivo, and transforms fibroblasts and hematopoietic target cells in vitro. We have used recombinant DNA technology to isolate and characterize the sequences that are essential in the transformation process. Integrated MC29 proviral DNA was isolated from a library of recombinant phage containing DNA from the MC29‐transformed nonproducer quail cell line Q5. The cloned DNA was analyzed by Southern blotting of restriction endonuclease digests and by electron microscopic visualization of R‐loops formed between the cloned DNA and MC29 or helper virus RNA. It was found that the 9.2 kb cloned DNA insert contains approximately 4 kb of viral sequences and 5.2 kb of quail cellular sequences. The viral sequences contain all of the MC29‐specific sequences and 5′ helper related sequences as well as part of the envelope region. The size of the cloned EcoRI fragment is the same as that of the major band in EcoRI‐cleaved Q5 DNA that hybridizes to viral sequences. Transfection of the cloned DNA into NIH 3T3 cells revealed that the MC29‐specific sequences are functional in that they induce foci of trans‐formed cells with high efficiency.
Identifying human cells capable of metabolizing various classes of carcinogens
Authors: Aust Ann E. , Antczak Michael R. , Maher Veronica M. , McCormick J. Justin 
Published: May 2005

AbstractHuman cells that appear capable of metabolizing various classes of carcinogens have been identified using one of two methods: metabolism of tritiated benzo(a)pyrene to aqueous‐acetone soluble forms or inhibition of cellular DNA synthesis. Each of the assay systems was optimized and the results on 15 human epithelial cell lines were compared. One or more cell lines were found to activate each of four classes of carcinogens examined: polycyclic hydrocarbons, aromatic amines, heterocyclic hydrocarbons, and nitrosamines. Cells that appeared capable of metabolizing polycyclic hydrocarbons or aromatic amines by these methods were also found to produce metabolites which were cytotoxic to cocultivated human xeroderma pigmentosum fibroblasts after a 48‐hr exposure to the carcinogen.
Molecular properties of a galaptin and its activity in normal and leukemic erythroid tissue
Authors: Godsave Susan F. , Harrison F. Lynne , Chesterton C. James 
Published: May 2005

AbstractRecently, the generic term “galaptins” was proposed for the group of low molecular weight, acidic, β‐galactoside‐specific protein lectins that have been isolated from a wide variety of animal tissues and are thought to have a role in cell‐cell recognition and adhesion. A molecule of this type, called erythroid developmental agglutinin (EDA), has been isolated from rabbit bone marow where it seems to mediate the intererythroblast adhesion seen in erythroblastic islands during erythropoiesis in vivo. Here, we show that after purification, EDA shows 95%‐100% Coomassie blue staining as a single component on electrophoresis in native, urea, and SDS polyacrylamide gels and electrofocuses as a single band at pH 5.6. EDA has a subunit molecular weight of 13,000 in SDS gels and, unlike the majority of other galaptins, which arc dimeric, native EDA is monomeric in solution. Another monomeric galaptin, chicken lactose lectin II, has been described recently, and it therefore seems that there may be two classes of galaptin distinguishable by their aggregation state in solution.We have previously reported that EDA agglutinates rabbit erythroblasts in vitro and that this reaction is inhibited by β‐galactoside‐containing sugars and by anti‐EDA Fab fragments suggesting that EDA bridges directly between cell surface glycoproteins. The insensitivity of this reaction to cooling, or to the disruption of cellular metabolism or the cytoskeleton demonstrated here further supports this hypothesis. EDA‐mediated erythroblast agglutination was also shown to be independent of divalent cations.Since galaptins are thought to be important in cohesion between normal cells, the possibility that EDA is not active in leukemic erythroid tissue was examined. The murine erythroleukemia cell line (MELC) provided an excellent system for this study since MELC are thought to be derived from an erythroid committed cell transformed at an early stage of development and can be induced by a number of chemical agents to differentiate terminally along the erythroid developmental pathway in culture. EDA of rabbit origin was found to agglutinate mouse erythroblasts in vitro and was used to investigate the response of MELC to EDA. It was found that the transformed cells were not readily agglutinated by EDA but on induction, and the concomitant loss of many of their transformed characteristics, MELC gained aggregation competence for EDA. The possible causes of these differences are discussed.
Kinetics of the reaction of carbon dioxide with blends of amines in aqueous media using the stopped‐flow technique
Authors: Ali Sami H. 
Published: May 2005

AbstractThe effect of mixing 2‐amino‐2‐methyl‐1‐propanol (AMP) with a primary amine, monoethanolamine (MEA), and a secondary amine, diethanolamine (DEA), on the kinetics of the reaction with carbon dioxide in aqueous media has been studied at 298, 303, 308, and 313 K over a range of blend composition and concentration. The direct stopped‐flow conductimetric method has been used to measure the kinetics of these reactions. The proposed model representing the reaction of CO2 with either of the blends studied is found to be satisfactory in determining the kinetics of the involved reactions. This model is based on the zwitterion mechanism for all the amines involved (AMP, MEA, and DEA). Blending AMP with either of the amines results in observed pseudo‐first‐order reaction rate constant values (ko) that are greater than the sum of the ko values of the respective pure amines. This is due to the role played by one amine in the deprotonation of the zwitterion of the other amine. Steric factor and basicity of the formed zwitterion and the deprotonating species have a great bearing in determining the rate of the reactions studied. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: 391–405, 2005
Theoretical study of thiolysis in penicillins and cephalosporines
Authors: Garcías Rafael C. , Coll Miguel , Donoso Josefa , Vilanova Bartolomé , Muñoz Francisco 
Published: May 2005

AbstractSemiempirical calculations were used to conduct a comprehensive study of the thiolysis of the fundamental core of penicillins and cephalosporins. The significance of the intramolecular protonation of the β‐lactam nitrogen in the formation and cleavage of the tetrahedral intermediate (T in Scheme 1) was examined in two thiols bearing substituents of different basicity in β with respect to the thiol group in the attacking nucleophile, namely 2‐mercaptoethanol (6) and 2‐mercaptoethylamine (7). Based on the results, the rate‐determining step in the reaction of penicillins is the cleavage of the tetrahedral intermediate, consistent with an intramolecular acid catalysis process in their thiolysis by 2‐mercaptoethylamine. On the other hand, the rate‐determining step in the reaction of cephalosporins, which possess an appropriate leaving group at position 3', is the formation of the tetrahedral intermediate, so the desolvation energy of the nucleophile is a major contributor to the overall energy of the process. This differential behavior between the two types of β‐lactam bicycles arises from the presence of the acetate group at 3' and the delocalization of π electrons over the N5–C4–C3 system in cephalosporins; this favors the formation of a thiolate with the 5‐ethoxymethylene‐1,3‐thiazine group in the cleavage of the tetrahedral intermediate, which is stabilized by an intramolecular hydrogen bond between N5 and the alcohol or amine group in β of the attacking thiol. The theoretical results are consistent with previous experimental data showing that, unlike penicillins, cephalosporins undergo no intramolecular acid catalysis in their thiolysis. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: 434–443, 2005
Rate constants for the reactions of chlorine atoms with hydrochloroethers at 298 k and atmospheric pressure
Authors: Dalmasso Pablo R. , Taccone Raúl A. , Nieto Jorge D. , Teruel Mariano A. , Lane Silvia I. 
Published: May 2005

AbstractThe relative rate technique has been used to determine the rate constants for the reactions Cl + CH3OCHCl2 → products and Cl + CH3OCH2CH2Cl → products. Experiments were carried out at 298 ± 2 K and atmospheric pressure using nitrogen as the bath gas. The decay rates of the organic species were measured relative to those of 1,2‐dichloroethane, acetone, and ethane. Using rate constants of (1.3 ± 0.2) × 10−12 cm3 molecule−1 s−1, (2.4 ± 0.4) × 10−12 cm3 molecule−1 s−1, and (5.9 ± 0.6) × 10−11 cm3 molecule−1 s−1 for the reactions of Cl atoms with 1,2‐dichloroethane, acetone, and ethane respectively, the following rate coefficients were derived for the reaction of Cl atoms (in units of cm3 molecule−1 s−1) with CH3OCHCl2, k= (1.04 ± 0.30) × 10−12 and CH3OCH2CH2Cl, k= (1.11 ± 0.20) × 10−10. Errors quoted represent two σ, and include the errors due to the uncertainties in the rate constants used to place our relative measurements on an absolute basis. The rate constants obtained are compared with previous literature data and used to estimate the atmospheric lifetimes for the studied ethers. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: 420–426, 2005
Kinetics and mechanism of benzoin oxidation using iron(III) in the presence of ferrozine or 2,2'‐bipyridine in acidic medium
Authors: Al‐Sou'od Khaldoun A. , Ali Basem F. , Abu‐El‐Halawa Rajab , Abu‐Nawas Abd‐Al‐Hakeem H. 
Published: May 2005

AbstractKinetics and mechanism of oxidation of benzoin (H2B) by ferrozine (Fz) or 2,2'‐bipyridine (bipy) have been carried out in aqueous HNO3 medium. The rate shows first‐order dependence on [H2B] and [Fe3+] and inverse second‐order dependence on [H+]. The rate of reaction increased with increase in the ligand concentration. The increase in dielectric constant will increase the rate, while increase in [HNO3] decreased it. Substituent and temperature effects on the rates have been investigated. The rate laws derived are in excellent agreement with the experimental results. Plausible mechanisms are suggested. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: 444–449, 2005
Conditions for selective photocatalytic degradation of naphthalene in triton X‐100 water solutions
Authors: Barrios Niurka , Sivov Paul , D'andrea Dora , Núñez Oswaldo 
Published: May 2005

AbstractNaphthalene is degraded selectively in surfactant Triton X‐100 water solutions when treated with disperse TiO2 catalyst and UV‐B simulated solar light. After complete degradation of the naphthalene, degradation of the Triton X‐100 commences. The pseudo‐first‐order kobs values obtained for both naphthalene and Triton X‐100 decrease with increasing Triton X‐100 concentration. Experimental rate values fit the Langmuir–Hinshelwood equations. An apparent rate constant for naphthalene degradation kN = 17.3 ppm min−1 and an adsorption equilibrium constant kN = 0.009 ppm−1 are obtained from a plot of 1/kobs vs. naphthalene concentration. An apparent rate constant for Triton X‐100 degradation kT, calculated from a 1/kobs vs. Triton X‐100 concentration plot of 1.1 ppm/min, was obtained. Therefore, the selectivity observed in naphthalene vs. Triton X‐100 degradation is then due to the favorable naphthalene rate constant degradation that more than balances its unfavorable adsorption equilibrium on the TiO2 surface. This result is quite important to establish actual experimental conditions for treatment of sites contaminated with polyaromatic hydrocarbons (PAH). © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: 414–419, 2005
Investigation of kinetic and mechanism of triphenylphosphine addition to para‐naphthoquinone
Authors: Nori‐Shargh Davood , Soofi Abolfazl , Farahani Nasrin Saroogh , Deyhimi Farzad 
Published: May 2005

AbstractThis work reports the results of a kinetic and mechanistic investigations of the addition reaction of triphenylphosphine to para‐naphtoquinone in 1,2‐dichloromethane as solvent. The order of reaction with respect to the reactants was determined using initial rate method, and the rate constant was obtained on the basis of pseudo‐first‐order method. Variable time method using Uv–Vis spectrophotometry (at 400 nm) was utilized for monitoring this addition reaction, for which the following Arrhenius equation was obtained:

equation image

The resulting activation parameters Ea, ΔH#, ΔG#, and ΔS# at 300 K were 13.63, 14.42, 18.75 kcal mol−1, and −14.54 cal mol−1K−1, respectively. The results suggest that the reaction is first order with respect to both triphenylphosphine and para‐naphthoquinone. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: 427–433, 2005
Experimental and kinetic modeling study of the effect of sulfur dioxide on the mutual sensitization of the oxidation of nitric oxide and methane
Authors: Dagaut Philippe , Nicolle André 
Published: May 2005

AbstractNew experimental results were obtained for the mutual sensitization of the oxidation of NO and methane in a fused silica jet‐stirred reactor operating at 105 Pa, over the temperature range 800–1150 K. The effect of the addition of sulfur dioxide was studied. Probe sampling followed by online FTIR analyses and off‐line GC‐TCD/FID analyses allowed the measurement of concentration profiles for the reactants, stable intermediates, and final products. A detailed chemical kinetic modeling of the present experiments was performed. An overall reasonable agreement between the present data and modeling was obtained. According to the present modeling, the mutual sensitization of the oxidation of methane and NO proceeds via the NO to NO2 conversion by HO2 and CH3O2. The conversion of NO to NO2 by CH3O2 is more important at low temperatures (800 K) than at higher temperatures (850–900 K) where the production of NO2 is mostly due to the reaction of NO with HO2. The NO to NO2 conversion is favored by the production of the HO2 and CH3O2 radicals yielded from the oxidation of the fuel. The production of OH resulting from the oxidation of NO accelerates the oxidation of the fuel: NO + HO2 → OH+ NO2 followed by OH + CH4→ CH3. In the lower temperature range of this study, the reaction further proceeds via CH3 + O2→ CH3O2; CH3O2+ NO → CH3O + NO2. At higher temperatures, the production of CH3O involves NO2: CH3+ NO2→ CH3O. This sequence of reactions is followed by CH3O → CH2O + H; CH2O +OH → HCO; HCO + O2 → HO2 and H + O2 → HO2 → CH2O + H; CH2O +OH → HCO; HCO + O2 → HO2 and H + O2 → HO2. The data and the modeling show that unexpectedly, SO2 has no measurable effect on the kinetics of the mutual sensitization of the oxidation of NO and methane in the present conditions, whereas it frequently acts as an inhibitor in combustion. This result was rationalized via a detailed kinetic analysis indicating that the inhibiting effect of SO2 via the sequence of reactions SO2+H → HOSO, HOSO+O2 → SO2+HO2, equivalent to H+O2HO2, is balanced by the reaction promoting step NO+HO2 → NO2+OH. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: 406–413, 2005
Hochtemperatur‐Korrosion durch Schwefelverbindungen in der Erdölraffination
Authors: Richards W. G. 
Published: May 2005

AbstractDem Angriff des wesentlichsten korrosiven Agens in Erdölraffinerien, dem Schwefelwasserstoff, bei hohen Temperaturen (über 260°C) widerstehen praktisch ausschließlich rostfreie, hochlegierte Stähle. Bei der Hochtemperatur‐Korrosion durch Schwefelwasserstoff sind neben der Temperatur auch Beanspruchungsdauer, Schwefelwasserstoff konzentration, Druck, Beschaffenheit des zu raffinierenden Öles und die Stahlqualität von Einfluß. Verfasser berichtet über die in den letzten Jahren in der BP‐Research Station durchgeführten Untersuchungen über die Korrosion von rostfreien Stählen durch Schwefelwasserstoff bei hohen Temperaturen, wobei allgemeine Oberflächen‐korrosion, interkristalline Korrosion und Spannungskorrosion der Stähle eingebend behandelt werden.
Ein thermodynamisches Kriterium für die Inhibition des Eisens mit Chromaten
Authors: Marković T. , Pavlović Z. 
Published: May 2005

AbstractZusammenstellung von Gleichgewichts‐Eh‐Werten Für die möglichen Elektrodenreaktionen im System Cr/Lösung. Die Bildungsaffinitäten werden graphisch aus der Beziehung: ΔF° = f (n. O.) bzw. ΔF° = f' (n. OH.) berechnet. Gebiete, in denen die Bildung von Chromoxyden und ‐Hydroxyden erfolgt, werden in einem Affinität (A)‐Überspannungs (ΔE)‐Diagramm dargestellt. Die vom pH‐Wert abhängige inhibierende Wirkung der Chromate wird durch die Affinitäten der chemischen Kopplungsreaktion der anodischen Fe‐Elektrodenreaktion und der kathodischen Cr‐Elektrodenreaktion erklärt.
Allgemeine Prüfungsmethoden im Zusammenhang mit Alterung und Korrosion von Kunststoffen
Authors: Mendrzyk H. 
Published: May 2005

AbstractNach einer kurzen Übersicht über die Ursachen und Vorgänge, die zur Alterung oder Korrosion von Kunststoffen führen, wurde auf die Möglichkeiten eingegangen, vorwiegend nach allgemein eingeführten (z. B. genormten) Methoden die bei der Lagerung und im Gebrauch eintretenden Vorgänge definiert nachzuahmen und zu beschleunigen. Dabei werden folgende Einwirkungen behandelt: Wärme, Sauerstoff (Ozon), Feuchtigkeit, Chemikalien, Organismen, Licht und Wetter sowie mechanische Dauerbeanspruchung. Beispiele wurden gegeben für kombinierte oder zeitlich aufeinanderfolgende Beanspruchungen, die den praktischen Verhältnissen näherkommen als die Einwirkung einzelner Komponenten. Schließlich wurden Hinweise auf die zweckmäßige Auswahl der Prüfmethoden gemacht, mit denen die eingetretenen Veränderungen festgestellt werden. Für die Planung derartiger Untersuchungen ist stets der Zweck maßgebend, er ist relativ sicher erreichbar, wenn die Korrelation zwischen Prüfverfahren und praktischer Bewährung durch Erfahrungen gesichert ist, aber nur mit Einschränkungen möglich, wenn es sich um die Beurteilung neuer Stoffe handelt, deren zukünftiges Verhalten vorausgesagt werden soll.
Korrosion in Warmwasserheizungen
Authors: Schmeken H. 
Published: May 2005

AbstractKorrosionsschäden in Warmwasserheizungen sind nur bei Eintritt von Sauerstoff möglich. In offenen Heizungen kann der für eine Korrosion notwendige Sauerstoff über Ausdehnungsgefäße infolge zu hohen Wasserdurchsatzes, bedingt durch ungünstige Schaltungen, über Pumpenanschlüsse oder durch falsche Betriebsweisen in das Heizungswasser gelangen. Auch in geschlossenen Anlagen tritt nur dann ein Korrosionsschaden oder die sekundär bedingte, störende Gaspolsterbildung auf, wenn zeitweilig Luftsauerstoff in das System gelangen kann. Die Art des Heizungswassers kann über eine Deckschichtbildung bei Sauerstoffzutritt die Korrosionsneigung verringern, so daß eine Enthärtung nur dann gewählt werden sollte, wenn sie zur Vermeidung von kritischer Wassersteinbildung erforderlich ist.