bluuebunny/crossref_metadata_2025_split huggingface dataset:
Repair of bleomycin‐damaged DNA by human fibroblasts
Authors: Hurt Myra M. , Beaudet Arthur L. , Moses Robb E. 
Published: May 2005

AbstractThe ability of human fibroblasts to repair bleomycin‐damaged DNA was examined in vivo. Repair of the specific lesions caused by bleomycin (BLM) was investigated in normal cell strains as well as those isolated from patients with apparent DNA repair defects. The diseases ataxia telangiectasia (AT), Bloom syndrome (BS), Cockayne syndrome (CS), Fanconi anemia (FA), and xeroderma pigmentosum (XP) were those selected for study. The method used for studying the repair of DNA after BLM exposure was alkaline sucrose gradient centrifugation. After exposure to BLM, a fall in the molecular weight of DNA was observed, and after drug removal the DNA reformed rapidly to high molecular weight. The fall in molecular weight upon exposure to BLM was observed in all cells examined with the exception of some XP strains. Prelabeled cells from some XP complementation groups were found to have a higher percentage of low molecular weight DNA on alkaline gradients than did normal cells. This prelabeled low molecular weight DNA disappeared upon exposure to BLM.
Double‐strand breaks in DNA caused by repair of damage due to ultraviolet light
Authors: Bradley Matthews O. 
Published: May 2005

AbstractDNA DSBs are formed in normal human IMR‐90 cells during repair incubation after 100 and 300 J·m−2 of UVL. By contrast, no DSBs are formed after UVL in human XPA cells that are unable to excise pyrimidine dimers. The DSBs are not due to immediate cell death since all the cells excluded trypan blue at the time of assay and because XPA cells, which are much more UVL‐sensitive than IMR‐90, did not form DSBs after UVL. We suggest that these repair‐induced DSBs should be potent lesions that might lead to cytotoxicity, chromosome aberrations, deletion mutations, and perhaps cellular transformation, transformation.
The structure of fibronectin and its role in cellular adhesion
Authors: Akiyama Steven K. , Yamada Kenneth M. , Hayashi Masao 
Published: May 2005

AbstractFibronectin is a large, adhesive glycoprotein which is found in a number of locations, most notably on cell surfaces, in extracellular matrixes, and in blood. Fibronectin has been detected in all vertebrates tested and in many invertebrates. Its presence in sponges is significant because this suggests that fibronectin may have appeared very early in evolution, possibly with the most primitive multicellular organisms. Cellular and plasma fibronectins have many striking similarities. However, the locations of the polypcptide chain differences between these two proteins indicate that plasma fibronectin cannot be derived from cellular fibronectin by means of simple post‐translational proteolysis. Instead, these different types of fibronectin may be products of different genes or of differentially spliced messenger RNA molecules. Amniotic fluid fibronectin is possibly a third form of the protein. Cellular and plasma fibronectins are composed of at least six protcaseresistant domains which contain specific binding sites for actin, gelatin, heparin, Staphylococcus aureus, transglutarninase, fibrin, DNA, and a cell surface receptor. The relative locations of these domains have been mapped in the primary structure of fibronectin. The cell surface receptor for fibronectin has not been positively identified, but may be a glycoprotein, a glycolipid, or a complex of the two. Although cell‐substratum adhesion is mediated by fibronectin, the locations of the areas of closest approach of the cell to the substratum (the adhesion plaques) and fibronectin are not coincident under conditions of active cell growth. Under conditions of cell growth arrest in low scrum concentrations, some fibronectin may become localized at the adhesion plaques. Models describing the domain structure of fibronectin and the molecular organization of the adhesion plaque area are presented.
Microchemical instrumentation
Authors: Hood Leroy , Hunkapiller Michael , Hewick Rodney , Giffin Charles E. , Dreyer William J. 
Published: May 2005

AbstractA number of cell surface molecules of great theoretical and practical importance simply cannot be obtained in amounts sufficient for molecular analysis using conventional methods and instrumentation. Because of our interest in such studies, we began about eight years ago to explore the possibility of developing new instrumentation for the sequence analysis of very small quantities of polypcptide chains. These efforts have led to the development of two microsequenators which employ one thousandth to one ten‐thousandth the material used in the original sequenator described by Per Edman. In addition, in conjunction with the explosion of recombinant DNA techniques, we also have begun to develop instrumentation for the sequence analysis and synthesis of DNA molecules. In this paper we describe briefly several new instruments that have been developed at Caltech. We believe this new instrumentation in conjunction with the recombinant DNA and hybridoma technologies will provide unique opportunities to analyze cell‐surface molecules in the years ahead.
Member‐associated changes during erythropoiesis. On the mechanism of maturation of reticulocytes to erythrocytes
Authors: Zweig Stephen E. , Tokuyasu K. T. , Singer S. J. 
Published: May 2005

AbstractThe mature mammalian erythrocyte has a unique membranoskeleton, the spectrin‐actin complex, which is responsible for many of the unusual membrane properties of the erythrocyte. Previous studies have shown that in successive stages of differentiation of the erythropoietic series leading to the mature erythrocyte there is a progressive increase in the density of spectrin associated with the membranes of these cells. An important stage of this progression occurs during the enucleation of the late erythroblast to produce the incipient reticulocyte, when all of the spectrin of the former cell is sequestered to the membrane of the reticulocyte. The reticulocyte itself, however, does not exhibit a fully formed membranoskeleton. In particular, the in vitro binding of multivalent ligands to specific membrane receptors on the reticulocyte was shown to cause a clustering of some fractions of these ligand‐receptor complexes into special mobile domains on the cell surface. These domains of clustered ligand‐receptor complexes became invaginated and endocytosed as small vesicles. By immunoelectron microscopic experiments, these invaginations and endocytosed vesicles were found to be specifically free of spectrin on their cytoplasmic surfaces.These earlier findings then raised the possibility that the maturation of reticulocytes to mature erythrocytes in vivo might involve a progressive loss of reticulocyte membrane free of spectrin, thereby producing a still more concentrated spectrin‐actin membranoskeleton in the erythrocyte than in the reticulocyte. This proposal is tested experimentally in this paper. In vivo reticulocytes were observed in ultrathin frozen sections of spleens from rabbits rendered anemic by phenylhydrazine treatment. These sections were indirectly immunolabeled with ferritin‐antibody reagents directed to rabbit spectrin. Most reticulocytes in a section had one or more surface invaginations and one or more intra‐cellular vesicles that were devoid of spectrin labeling. The erythrocytes in the same sections did not exhibit these features, and their membranes were everywhere uniformly labeled for spectrin. Spectrin‐free surface invaginations and intracellular vesicle were also observed with reticulocytes within normal rabbit spleens. Based on these results, a scheme for membrane remodeling during reticulocyte maturation in vivo is proposed.
Factors implicated in determining the structure of zinc tubulin‐sheets: Lateral tubulin–tubulin interaction is promoted by the presence of zinc
Authors: de la Torre J. , Villasante A. , Corral J. , Avila J. 
Published: May 2005

AbstractAddition of increasing amounts of zinc to a cold microtubule protein solution results in the disappearance of 30 S oligomer found in the absence of that cation and in the appearance of new tubulin oligomers, 90 S and 23 S. When a microtubule protein solution is warmed in the presence of zinc, tubulin‐sheets are assembled. We have tested the influence of microtubule associated proteins and the zinc:tubulin ratio on the polymerization process. Depletion of microtubule associated proteins results in wider and longer tubulin‐sheets than those polymerized in the presence of microtubule associated proteins. However by increasing zinc concentration wider but shorter tubulin‐sheets were found. These results suggest that microtubule associated proteins and zinc could promote nucleation of tubulin‐sheets, but zinc also promotes lateral tubulin‐tubulin interaction. This interpretation was confirmed when microtubule protein was assembled at a low zinctubulin ratio. In such conditions composite structures of microtubules and zinc tubulin‐sheets arc formed. These composite structures are consequence of a lateral attachment of a zinc tubulin‐sheet on a microtubule protofilament.
Alkylation of DNA and tissue specificity in nitrosamine carcinogenesis
Authors: Montesano Ruggero 
Published: May 2005

AbstractA peculiarity of nitrosamines is the high degree of cell and organ specificity in inducing tumors. There is substantial evidence that the initiation of the carcinogenesis process by carcinogens of this group is linked to the metabolic competence of the target tissue or cell to convert these carcinogens into mutagenic metabolites and to the binding of those metabolites to cellular DNA. Alkylation occurs in the DNA at the N‐1, N‐3, and N‐7 positions of adenine; the N‐3, N‐7, and O6 of guanine; the N‐3, and O2 of cytosine; and the N‐3, O4, and O2 of thymine; and the phosphate groups. The initial proportion of each DNA adduct depends upon the alkylating agent used. The various DNA adducts are lost to a variable extent from DNA in vivo by spontaneous release of bases and Or by specific DNA repair processes. Studies conducted in vitro and in vivo indicate that alkylation at the oxygen atoms of DNA bases is more critical than alkylation at other positions in the mutagenesis and carcinogenesis induced by N‐nitroso compounds. In particular, tissues in which tumors occur more frequently after a pulse dose of nitrosamine are those in which O6‐alkylguanine persists longest in DNA, presumably resulting in an increased probability that a miscoding event (mutation) will take place during DNA synthesis. The more rapid removal of O6‐methylguanine from the DNA of liver (as compared with cxtrahepatic tissues) of rats has been associated with the absence of tumor production in this organ by a single dose of dimethylnitrosamine; however, a significant incidence of liver tumors is observed if the same dose is given 24 hr after partial hepatectomy, and tumors arc induced by such a dose of dimethyl‐nitrosamine in the liver of hamsters, which has a low capacity to remove O6‐methylguanine from its DNA. These data also indicate that the rate of disappearance of 7‐methylguanine from the liver or cxtrahepatic tissues is independent of the dose of dimethylnitrosamine; whereas O6‐methylguanine is lost from DNA more rapidly after a low dose of this nitrosamine. It has been shown that in liver the removal of O6‐methylguanine, but not of other DNA adducts, from DNA can be affected by pretreating the animals with N‐nitroso compounds. The modulation of DNA repair processes observed after a single dose and after chronic treatment with nitrosamines is discussed in relation to the tissue‐specific carcinogenic effect of this group of carcinogens.
Anomalous cell surface structure of sickle cell anemia erythrocytes as demonstrated by cell surface labeling and endo‐β‐galactosidase treatment
Authors: Fukuda Minoru , Fukuda Michiko N. , Hakomori Sen‐Itiroh , Papayannopoulou Thalia 
Published: May 2005

AbstractErythrocyte surface glycoproteins from patients with various types of sickle cell anemia have been analyzed and compared with those from normal individuals. By hemagglutination with various anti‐carbohydrate antibodies, sickle cells showed profound increase of i antigens and moderate increase of GlcNAcβ1→3Galβ1→3Glc structure, whereas antigenicity toward globosidic structure was unchanged. In parallel to these findings, erythrocytes of sickle cell patients have additional sialylatcd lactosaminoglycan in Band 3. Thus, it can be concluded that erythrocytes of sickle cell patients are characterized by an altered cell surface structure which does not appear to be due to topographical changes of cell surface membrane. It is possible that the anemia or the “stress” hematopoiesis in these patients is responsible for these changes.
Beitrag zur Entwicklung der Neoprene‐Auskleidungen zum Schutze chemischer Apparate
Authors: Tixier M. 
Published: May 2005

AbstractDas Verfahren der Auskleidung von Apparaten mit vorvulkanisierten Neoprene‐Platten wird in seinen einzelnen Stufen erläutert. Anschließend werden 7 Fälle beschrieben, in denen sich diese Auskleidungen bewährt haben.
Zur Photochemie des metallischen Kupfers und deren Einfluß auf die Auflösungsgeschwindigkeit von Kupfer in Elektrolyten
Authors: Marković T. , Balaš M. , Esih I. 
Published: May 2005

AbstractDurch Ätzung von Kupfer mit einem HNO3‐HCl‐Gemisch entsteht eine photoaktive Kupferschicht, die nach Belichtung eine zeitlich abhängige Schwärzung aufweist. Bei der Belichtung mit einer 6,7 V‐Glühlampe in einem Abstand von 10 cm wird auf der Kupferoberfläche ein Lichtfleck von etwa 1,75 cm2 gebildet. In bestimmten Zeitintervallen treten sodann drei Diskontinuitäten auf. Die Intensität der Reflexion wurde mit Photozelle und Spiegelgalvanometer registriert. Die Erhöhung der Temperatur führt zur Verminderung der Schwärzungsgeschwindigkeit der photoaktiven Schicht.Die Beobachtungen über den Einfluß des Lichtes auf die Auflösungsgeschwindigkeit des Kupfers in Elektrolyten ergaben eine typische Abhängigkeit der Korrosionsgeschwindigkeit von der an der Kupfer‐Oberfläche stattgefundenen Reaktion.
Temperatur‐, wärme‐ und hitzebeständige Anstriche auf Stahl
Authors: van Oeteren K. A. 
Published: May 2005

AbstractFür den Anstrich von Abgaskaminen, Öfen, Heizkörpern, Rohrleitungen für heiße Flüssigkeiten und Gase, Motore, Auspuffrohre und Gichtgasleitungen sind die normalen Anstrichmittel in der Regel unbrauchbar. Es sin daher spezielle Anstrichmittel erforderlich.Bei der Temperaturbeanspruchung eines Anstriches ist zu unterscheiden zwischen: Höhe der Temperatur, Maximal‐ und Dauertemperatur, trockene oder feuchte Wärme, Innen‐oder Außenbeanspruchung, Temperaturwechselbeanspruchung kalt ⇌ warm, Dauer der Temperatur.Die Temperaturbeanspruchung eines Anstriches ist daher von verschiedenen Faktoren abhängig, die erst zusammen eine Aussage gestatten. Von besonderer Bedeutung ist die Temperaturbeständigkeit des Bindemittels und der Einfluß der Pigmente, ferner die Gasdurchlässigkeit (Unterzunderung), die Ausdehnung von temperaturbeständigen Anstrichen durch thermische Einwirkung.Vor Einsatz eines Anstrichmittels ist eine Prüfung der Temperaturbeständigkeit erforderlich. Vor Anstrich eines temperaturbelasteten Objektes ist eine Temperaturermittlung erforderlich. Die Art der Entrostung, die Anzahl der Anstriche, die Art der Anstrichtechnik und der Anstrichausführung ist bei temperaturbeanspruchten Objekten von grosser Bedeutung.
Über die Polarisationserscheinungen bei der Abscheidung von glatten Bleiüberzügen aus einem neuen, komplexen Bleiacetatbad
Authors: Machu Willibald , Lotfy Badawy M. Ali El Sayed 
Published: May 2005

AbstractDie Stromdichte‐Potential‐Kurven in Lösungen von Komplexverbindungen des Bleisulfats in Bleiacetat und Ammoniumacetat lassen den Schluß zu, daß die Kornverfeinerung nicht auf eine stärkere kathodische Polarisation zurückzuführen ist. Maßgebend dafür ist vielmehr die Blockierung der aktiven Zentren an der Kathodenoberfläche. Dadurch wird das sonst vorherrschende Wachstum der Bleikristalle in Senkrechter Richtung zur Kathodenoberfläche und parallel zu den Stromlinien unterbunden. Das komplex gelöste Bleisulfat wirkt stärker kornverfeinernd als organische Zusätze im Bad.
Die Wirkung korrosiver Atmosphären auf Niederspannungsisolierungen
Authors: Sachsenweger C. , Hänsele K. , Stimper K. , Sockel H. G. 
Published: May 2005

AbstractDas Isolationsverhalten elektrotechnischer Erzeugnisse wird beeinträchtigt, wenn leitfähige Korrosionsprodukte zwischen spannungsführende Elektroden gelangen. Zur zeitraffenden Simulation dienen genormte Prüfverfahren mit SO2‐ bzw. H2S‐haltigen korrosiven Atmosphären. Die Wirkung derartiger Prüfungen wurde an Prüflingen aus Al2O3‐Keramikplättchen mit gleichspannungsbeanspruchten Elektrodenpaaren aus Kupfer, Messing oder Lötzinn untersucht. Mit Hilfe von SIMS‐Analysen wurde festgestellt, daß bei H2S‐Einwirkung auf Kupfer und Messing sulfidhaltige Korrosionsprodukte in den Elektrodenzwischenraum gelangten. Vereinzelt unter SO2‐Einwirkung entstandene leitende Verbindungen zwischen Messing‐ und Lötzinnelektrodenpaaren sind demgegenüber wahrscheinlich auf vorgewachsene Metalldendriten zurückzuführen.
Werkstoff‐Datenbank
Authors: Kirchheiner R. , Kowalski (Acosta) P. , Hartung T. 
Published: May 2005

AbstractDie neu entwickelte Sollwert‐Werkstoff‐Datenbank (SWDB) ist eine benutzerfreundliche Werkstoff‐Datenbank, die Informationen über genormte und nicht genormte Werkstoff‐Kennwerte massiver, metallischer Werkstoffe bereitstellt. Der Inhalt dieser Datenbank setzt sich zusammen aus Solldaten von ingenieurmäßig gebräuchlichen, massiven Werkstoffen aus Eisen‐ und Nichteisenmetallen. Neben der chemischen Zusammensetzung und den mechanisch‐technologischen Eigenschaften von metallischen Werkstoffen nach verschiedenen Normen und Spezifikationen sind eine Vielzahl möglicher alternativer Werkstoffkandidaten in kurzer, prägnanter und für den Anwender gut einsehbarer Form referiert. Die Daten sind auf der Basis eines völlig neu strukturierten Modells aufgebaut und in Abhängigkeit vom spezifizierten Werkstoff von der Erzeugnisform, der Abmessung, dem Lieferzustand und von der Probennahme wiedergegeben.Außerdem enthält die SWDB zusätzliche Informationen über physikalische Kennwerte sowie zahlreiche Angaben zur Wärmebehandlung, Warm‐ und Kaltformgebung, Schweißbarkeit und Anwendungshinweise. Die SWDB hat eine doppelte Funktion: einerseits arbeitet sie als unabhängige Datenbank eigenständig, andererseits als Satellit‐Datenbank, die die Korrosionsfakten‐Datenbank im Informationssystem für Korrosion und Korrosionsschutz „CORIS”︁ unterstützt.
Mass spectrometry of sulfur‐containing compounds in organic and bioorganic fields
Authors: Bortolini O. , Fogagnolo M. 
Published: May 2005

AbstractThis survey covers the mass spectrometic properties of organosulfur compounds containing the sulfide, disulfide, and sulfone functional groups. Attention is paid to the uni‐ and biomolecular chemistry of both positive and negative ions, as well as to the reactions of ions, with sulfur containing species, in the gas phase. The role of other functional groups on the decomposition of organic S, SO, SO2 containing gaseous ions is also discussed. The selection of sulfur containing compounds includes many naturally occurring and pharmaceutically significant products, that will be presented in the following order: alkaloids, amino acids, peptides, proteins, carbohydrates, steroids, and metabolites. © 1996 John Wiley & Sons, Inc.
Ions in the terrestrial atmosphere and in interstellar clouds
Authors: Smith David , Spanel Patrik 
Published: May 2005

AbstractIons are formed in the terrestrial atmosphere (TA) and in interstellar clouds (ISC) by the action of solar/stellar UV and cosmic rays on the ambient neutral atmospheres. The precursor ions so formed develop largely via gas‐phase ion chemistry from the simple ions characteristic of the ambient atmospheres to the observed, more complex ions. In the upper TA and in ISC, only bimolecular ion chemistry occurs. In the tenuous upper TA, the ion types remain simple, O+, O, and NO+ being dominant, and similarly in the tenuous diffuse ISC, ions such as H+, H22+, C+, and CH+ are dominant. At the high pressures of the lower TA, termolecular association reactions are important, and the initial ions, e.g., O and N formed by cosmic ray ionization are quickly converted to very complex cluster ions of the type H+(H2O)n (bases)m with bases including NH3 and CH3CN, and a parallel negative ion chemistry develops from the primary negative ions O− and O producing ions like NO(H2O)n(acid)m with acids HNO3 and H2SO4. In the dense ISC, the ion chemistry proceeds to produce polyatomic ions from the most important initial ions C+, H, and CH, and the process of radiative association, the bimolecular analog of termolecular association, is important in producing, for example, ions such as CH M, where M are the common observed interstellar molecules such as the carboxy, cyano, and amino molecules, which are formed via this ion chemistry. The major ion neutralization process in the upper TA and in ISC is positive ion–electron recombination, which limits the degree of ionization in these regions, whereas in the lower TA, where negative ions balance the positive ions, the charge neutralization process is ion–ion recombinarion. © 1996 John Wiley & Sons, Inc.
Untersuchungen über den Einfluß von Prüfparametern und subjektiven Beurteilungsmaßstäben beim Nachweis von Rissen mittels Röntgendurchstrahlung
Authors: Echterhoff U. 
Published: May 2005

AbstractAnhand eines praktischen Prüffalles werden die von der Bruchmechanik vorgegebenen Anforderungen an die Durchstrahlungsprüfung und deren Möglichkeiten zur Lösung der anstehenden Probleme diskutiert. Anforderungen der DIN 54 111 werden bei den Untersuchungen berücksichtigt und ihre Einflüsse auf die subjektiven Beurteilungskriterien beim Nachweis feiner Risse überprüft. Durch gezielte Variationen und kritische Einschränkung der Daten nach DIN 54 111 können bei der Durchstrahlungsprüfung ausreichende Auskünfte über das Vorhandensein von Fehlern gewonnen werden.
Investigations on Stress corrosion cracking of sensitized austenitic stainless steels and nickel‐base alloys in boiling aqueous solutions by potentiostatically controlled constant‐load experiments
Authors: Herbsleb Günter 
Published: May 2005

AbstractThe susceptibility of high alloyed materials to intergranular SCC is markedly influenced not only by material and environmental parameters, but also by the potential. The present paper describes in detail the influence of the potential on the susceptibility to intergranular SCC of these materials in aqueous solutions boiling under normal pressure by means of potentiostatically controlled constant load experiments. The following parameters have been varied:
Material

alloy composition: 18/10 non‐stabilized stainless steel; Incoloy 800; Inconel 600;
degree of sensitization;
pre‐damage by intergranular attack, caused in sulfuric acid/copper sulphate‐solution;
level of mechanical stresses.

Environment

sodium chloride concentration;
sodium sulphate concentration;
pH (buffer solutions of pH 2.2 and 4.5).

Potential

The test‐duration was up to several thousand hours.The type of attack – intergranular corrosion, intergranular and/or transgranular cracking – has been established by metallografic investigations. The experimental results are presented in form of time‐to‐failure/potential curves with the above mentioned parameters. Conclusions for the in‐service behaviour of the materials investigated are derived.