bluuebunny/crossref_metadata_2025_split huggingface dataset:
The glutamate transporter EAAT2 is transiently expressed in developing human cerebral white matter
Authors: Desilva Tara M. , Kinney Hannah C. , Borenstein Natalia S. , Trachtenberg Felicia L. , Irwin Nina , Volpe Joseph J. , Rosenberg Paul A. 
Published: February 2007

AbstractThe major brain abnormality underlying cerebral palsy in premature infants is periventricular leukomalacia (PVL), a lesion of the immature cerebral white matter. Oligodendrocyte precursors (pre‐OLs; O4+O1−) predominate in human cerebral white matter during the peak time frame for PVL (24–32 gestational weeks) and are vulnerable to excitotoxicity. We hypothesize that PVL reflects, in part, excitotoxicity to pre‐OLs resulting from cerebral ischemia/reperfusion. Reversal of glutamate transport in the setting of energy failure is a major source of pathologic accumulation of extracellular glutamate. Here, we identify and localize the glutamate transporters in human cerebral white matter during the age range of PVL. In situ hybridization was performed with digoxigenin‐labeled probes directed against the full‐length coding regions of EAAT1, EAAT2, and EAAT3. EAAT2 mRNA was abundant in human fetal white matter during the period of peak incidence of PVL and virtually disappeared by 2 postnatal months. Its developmental profile differed significantly from that of both EAAT1 and EAAT3 mRNA. Immunoblotting demonstrated that EAAT2 protein was highly expressed in early development relative to adult values. Double‐label immunocytochemistry detected EAAT2 in OLs but not astrocytes or axons in the human fetal white matter. We conclude that transient expression of EAAT2 occurs during the window of peak vulnerability for PVL, suggesting that this developmentally up‐regulated transporter may be a major source of extracellular glutamate in ischemic injury to the cerebral white matter of the preterm infant. J. Comp. Neurol. 501:879–890, 2007. © 2007 Wiley‐Liss, Inc.
Untersuchungen zur Vermeidung von Rißschäden bei nicht tragenden Trennwänden
Authors: Brameshuber Wolfgang , Beer Ingo , Kang Bong‐Gu 
Published: February 2007

AbstractBislang werden die Verformungen von Stahlbetonbauteilen unter nicht tragenden Trennwänden nach DIN 1045‐1 auf 1/500 der Stützweite beschränkt, um Rißschäden in den Wänden zu vermeiden. Abgeleitet wurde dieser Richtwert durch Analyse von Bauschäden in den 60er Jahren. Direkte Untersuchungen zum Tragverhalten und damit auch zur Entstehung von Rissen in nicht tragenden Trennwänden wurden erst vor kurzem in einem vom Bundesamt für Bauwesen und Raumordnung geförderten Forschungsprojekt am Institut für Bauforschung durchgeführt.In diesem Beitrag wird über die Ergebnisse des Forschungsprojektes, das sowohl einen Baustellenversuch an einer nicht tragenden, geschoßhohen Trennwand als auch Laborversuche und Finite‐Elemente‐Simulationen an geschoßhohen Wänden beinhaltet, berichtet.
Nachweis der Schubtragfähigkeit mit dem angepaßten Nachweisformat nach DIN 1053‐100
Authors: Kranzler Thomas , Schöps Peter 
Published: February 2007

AbstractMit dem Übergang auf das neue Sicherheitskonzept verschärfen sich durch zu untersuchende Lastkombinationen die Beanspruchungen auf aussteifende und stabilisierende Bauteile eines Gebäudes. Der Grund dafür liegt in der bauartunabhängigen Festlegung der Teilsicherheitsbeiwerte in Deutschland. Weiterhin haben sich im Rahmen der Überarbeitung der Normen für die Tragwerkseinwirkungen die anzusetzenden Horizontallasten infolge Wind und Erdbeben signifikant erhöht. Bei der gleichzeitig vom Bauherrn angestrebten Optimierung von Nutzflächen stehen diesem Sachverhalt immer geringer werdende Querschnittsflächen der Aussteifungswände gegenüber. Der Nachweis der Schubtragfähigkeit gewinnt damit vermehrt an Bedeutung. Auf der Widerstandseite steht dem mit DIN 1053‐100 nun eine Norm gegenüber, welche unter weitgehender Beibehaltung des bisherigen Status Quo von DIN 1053‐1 die Anwendung des Teilsicherheitskonzeptes bei der Bemessung von Mauerwerksbauten ermöglicht. Der vorliegende Beitrag befaßt sich mit dem Nachweis der Schubtragfähigkeit von unbewehrtem Mauerwerk nach DIN 1053‐100. Es werden die wesentlichen Neuerungen hinsichtlich der Nachweisführung sowie deren Hintergründe und Auswirkungen insbesondere hinsichtlich des neuen Sicherheitskonzeptes vorgestellt.
Tragfähigkeit von unbewehrtem Mauerwerk unter zentrischer und exzentrischer Druckbeanspruchung nach DIN 1053‐100
Authors: Graubner Carl‐Alexander , Jäger Wolfram 
Published: February 2007

AbstractDer Beitrag befaßt sich mit der Tragfähigkeit von unbewehrtem Mauerwerk unter zentrischer und exzentrischer Druckbeanspruchung bei Anwendung des genaueren Berechnungsverfahrens nach DIN 1053‐100.Mit dem Übergang auf das neue Sicherheitskonzept ist die Nachweisführung bei zentrischer und exzentrischer Beanspruchung auf den in Europa inzwischen üblichen Spannungsblock umgestellt worden. Die Berechnung wird dadurch erleichtert. Die Erfassung der Traglastminderung infolge exzentrischer Beanspruchung erfolgt über einen Abminderungsfaktor gegenüber der vollen Tragkraft bei zentrischer Kraftwirkung. Der Knicknachweis wird ebenfalls über einen Abminderungsfaktor, der in Wandmitte neben der exzentrischen Druckkraft auch die Anteile aus Theorie II. Ordnung berücksichtigt, geführt. Neue Erkenntnisse im Hinblick auf Tragreserven sind dabei eingeflossen. In dem Beitrag werden die Hintergründe und die Nachweisführung erläutert und auch die Auswirkungen auf die Systemtragfähigkeit von Mauerwerkswänden behandelt. Abgerundet wird die Thematik durch eine Gegenüberstellung der Traglasten nach DIN 1053‐1 und DIN 1053‐100.
Der Randdehnungsnachweis und seine Anpassung zur konsequenten Anwendung von DIN 1055‐100
Authors: Hoffmann Jens , Schöps Peter 
Published: February 2007

AbstractDie bauaufsichtliche Einführung der neuen Windlastnorm DIN 1055‐4:2005‐03 bringt für viele Gebäudestandorte Windlasterhöhungen mit sich, die insbesondere den Nachweis von Schubwänden in Einfamilienreihenhäusern erschweren oder unmöglich machen können. Bemessungsmaßgebend wird hier oftmals der Randdehnungsnachweis. Der Beitrag beleuchtet die Sonderstellung von Schubscheiben in Einfamilienreihenhäusern und den Hintergrund des Randdehnungsnachweises. In diesem Zusammenhang wird über einen Vorschlag zur Kompensation der Mehrbelastung durch konsequente Anwendung der Lastkombinationsregeln in DIN 1055‐100 berichtet und abschließend eine Bemessungshilfe in Form eines Diagramms vorgestellt.
Synthesis and Structural Investigation of C4‐ and C2‐Symmetric Molecular Scaffolds Based on Imidazole Peptides
Authors: Haberhauer Gebhard , Pintér Áron , Oeser Thomas , Rominger Frank 
Published: February 2007

AbstractThe syntheses of a C4‐ and a C2‐symmetric scaffold are presented. The first is composed of four imidazole units, while the second contains two imidazole and two oxazole moieties. The synthesis of the key building block for both systems has been fundamentally improved. Starting from these scaffolds, various platforms possessing two or four arms can easily be prepared. The structures of the scaffolds, together with that of a C4‐symmetric oxazole scaffold, were investigated in the solid state and in the gas phase. We found that these 24‐membered cyclic peptides exist as two different structure types. In one case (type I), the nitrogen atoms of the azole units pointing into the interior of the macrocycle form a square, whereas in the second case (type II), they form a parallelogram. The type of molecular structure does not depend on the symmetry of the system, but on the type of azole used. Cyclic systems composed of four imidazole units are present in the type I structure, whereas systems consisting of four oxazole units exhibit the type II nature. Structure type II is also present in cycles composed of two oxazole units and two imidazole units. The existence of the different structure types can be explained in terms of the different orbital energies of the imidazole and oxazole systems. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Short Synthesis of Orthogonally Protected 3α,12α‐Diamino‐5β‐cholan‐24‐oic Acid, a Dipodal Steroid Scaffold for Combinatorial Chemistry
Authors: Verzele Dieter , Madder Annemieke 
Published: February 2007

AbstractA short, practical, multigram‐scale synthesis of C3α‐NHAlloc, C12α‐NHBoc‐diamino‐5β‐cholan‐24‐oic acid 2 was developed, applying a new, straightforward synthetic strategy. Key features are the conservation of the carboxyl moiety at C24 during oxime reduction, the late differentiation between the C3 and C12 amino groups and the gradual separation of diastereomers during the synthesis. This orthogonally protected diamino steroid derivative can be used as starting point for the generation of steroid based dipodal peptide and non‐peptide combinatorial libraries. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Adding minority status to a source of conflict: an examination of influence processes and product quality in dyads
Authors: Smith Christine M. 
Published: February 2007

AbstractMinority influence and conflict exposure were studied in an additive fashion within discussion dyads to clarify the role each plays in divergent thinking. Dyad types (determined by each member's preference for a political candidate) included: No conflict (both members preferred the same candidate, conflict only (each member preferred a different candidate), and minority status plus conflict (same as conflict only with one candidate labeled the minority candidate). Dyads chose a candidate, brainstormed to solve a problem, chose one solution and developed a proposal, and evaluated their interaction. The results showed that minority dyads' discussions of the political candidates were robust and resulted in direct minority influence. Additionally, brainstorming and proposal quality were positively affected by the minority source of influence. It appears that the status of the source of conflict plays a critical role in divergent thinking. Additionally, group products appear to be affected by individual divergent thinking. Copyright © 2007 John Wiley & Sons, Ltd.
A study on the condition for differential electrophoretic transport at a channel entrance
Authors: Pacheco J. Rafael , Chen Kang Ping , Hayes Mark A. 
Published: February 2007

AbstractElectrophoretic differential transport of ionic species in a solution moving from a large reservoir into a small channel is investigated numerically. The system setup is similar to the experiments of Polson, Savin, and Hayes (J. Microcol. Sep. 2000, 12, 98), where the bulk flow into a fused‐silica capillary was driven by a pressure differential. A critical condition for achieving the defined differential transport near the channel entrance is found and this condition is solely determined by a dimensionless parameter when the geometry of the system is prescribed. This dimensionless parameter is the ratio between the electrophoretic migration velocity of the species based on the apparent electric intensity and the centerline fluid velocity of the fully developed channel flow. Species concentration distributions are also computed for various conditions. A separation technique can be derived from the experimental condition where a targeted division of species can be created at the channel entrance.
Design, characterization, and utilization of a fast fluorescence derivatization reaction utilizing o‐phthaldialdehyde coupled with fluorescent thiols
Authors: Hapuarachchi Suminda , Aspinwall Craig A. 
Published: February 2007

AbstractWe have developed a chemical derivatization scheme for primary amines that couples the fast kinetic properties of o‐phthaldialdehyde (OPA) with the photophysical properties of visible, high quantum yield, fluorescent dyes. In this reaction, OPA is used as a cross‐linking reagent in the labeling reaction of primary amines in the presence of a fluorescent thiol, 5‐((2‐(and‐3)‐S‐(acetylmercapto)succinoyl)amino)fluorescein (SAMSA fluorescein), thereby incorporating fluorescein (ϵ = 78 000 M−1, quantum yield of 0.98) into the isoindole product. Detection is based on excitation and emission of the incorporated fluorescein using the 488 nm laser line of an Ar+ laser rather than the UV‐excited isoindole, thereby eliminating the UV light sources for detection. Using this method, we have quantitatively labeled biologically important primary amines in less than 10 s. Detection limits for analysis of glutamate, glycine, GABA, and taurine were less than 2 nM. We present the characterization of OPA/SAMSA‐F reaction and the potential utility of the derivatization reaction for dynamic chemical monitoring of biologically relevant analytes using CE.
Tem‐induced gene mutations at enzyme loci in the mouse
Authors: Soares E. R. 
Published: February 2007

AbstractStrain DBA/2J male mice were treated with triethylenemelamine (TEM) and subsequently mated to strain C57BL/6J females. Tissues from F1 progeny produced in these crosses were then examined using starch gel electrophoresis for the presence of presumed induced mutations at a series of 11 specific enzyme loci. In the course of this study, four heritable mutations were identified at the following loci: Es‐1, Ldh‐1, Pgm‐1, and Gpi‐1. Of these four, the first two were apparently segregating in parental males and were not TEM‐induced. Both of these are viable and fertile in the heterozygous and homozygous condition, and neither confers any readily apparent deleterious effect to the animal. The latter mutations (Pgm‐1 and Gpi‐1) are presumably induced. Although viable and fertile in the heterozygous state, we have not yet recovered any offspring homozygous for either of these two mutations.
Studies on the clastogenic effects of biologic stains and dyes
Authors: Au William , Hsu T. C. 
Published: February 2007

AbstractWe have surveyed the clastogenic potential of 12 different groups of stains and dyes totalling 48 compounds. We observed that 18 compounds induced significant increase in chromosome damage. Most of them were also found to be mutagenic, carcinogenic, or toxic in other reported studies. However, no significant studies were reported on six of them. It is concluded that these agents are potentially hazardous and should be studied further in detail.
A colorimetric assay of lysogenic induction designed for screening potential carcinogenic and carcinostatic agents
Authors: Elespuru R. K. , Yarmolinsky M. B. 
Published: February 2007

AbstractSimple, rapid colorimetric tests for lysogenic induction (the derepression of a latent bacterial virus) are described. A quantitative test and a more rapid semiquantitative test are based on the assay of the β‐galactosidase synthesized from a lacZ gene fused to an operon under lambda repressor control. These biochemical “inductests” are suitable for screening programs designed to detect agents that damage DNA and that are of potential interest in carcinogenesis and cancer chemotherapy.
Effect of the co‐carcinogen benzo[e] pyrene on microsome‐mediated chemical mutagenesis in salmonella typhimurium
Authors: Kameswar Rao T. , Young J. A. , Weeks C. E. , Slaga T. J. , Epler J. L. 
Published: February 2007

AbstractChemical agents that possess the ability to alter tumorigenicity of carcinogens (administered at subthreshold dose) constitute a major health hazard. We have employed the Ames Salmonella assay to examine the effect of co‐carcinogenic benzo[e] pyrene (B[e]P) on microsome‐mediated chemical mutagenesis. B[e]P enhanced the mutagenic activity induced by 2‐acetylaminofluorene (2‐AAF) and benzo[a] pyrene (B[a]P) in strains TA1538 and TA98. Enhancement was also noted with N‐hydroxy‐2‐AAF (the proximal metabolite of 2‐AAF) but not with an ultimate carcinogenic form (N‐acetoxy‐2‐AAF). These results suggest the use of this approach to detect chemical agents that possess the ability to alter the activity of mutagenic or carcinogenic chemicals.
Problems associated with the application of short‐term tests for mutagenicity in mass‐screening programs
Authors: De Serres Frederick J. 
Published: February 2007

AbstractDuring the past ten years we have made a great deal of progress toward the general acceptance of the need for mass‐screening programs to identify environmental chemicals with mutagenic activity. At every meeting of this society new examples are given of mutagens to which substantial portions of the population are exposed. But as a group we are still wrestling with the problem of the development of an effective mechanism for such testing on a still larger scale. It is the problems associated with the development of these mass‐screening programs that I want to bring to your attention this afternoon.
Mutagenicity of nitrosocarbaryl and other methylating nitrosamides as related to uptake in haemophilus influenzae
Authors: Elespuru R. K. 
Published: February 2007

AbstractDifferences greater than 6,000‐fold in the mutagenic potency of three nitro‐samides that are methylating agents [N‐methyl‐N‐nitrosourea (MNU), N‐methyl‐N′‐nitro‐N‐nitrosoguanidine (MNNG) and N‐nitrosocarbaryl (NC)] could be accounted for in part by differences in their uptake into the Haemophilus influenzae cells. Uptake was roughly correlated with the octanol/water partition coefficient. The most potent mutagen, NC, was concentrated by the cells. The least potent, MNU, was essentially excluded from the bacteria. Uptake was a linear function of concentration, whereas induction of novobiocin‐resistant mutations followed higher‐order kinetics. The effective dose of chemical to the bacteria (number of molecules taken up) under conditions of mutagenesis could be calculated.
Bile as a source of mutagenic metabolites produced in vivo and detected by salmonella typhimurium
Authors: Connor T. H. , Cantelli Forti G. , Sitra P. , Legator M. S. 
Published: February 2007

AbstractThe in vivo metabolic activation of several mutagenic compounds was assayed in the bile of rats, with Salmonella typhimurium as the indicator organism. It was determined that for some compounds, particularly the aromatic amines, a substantial percentage of the compound was excreted into the bile as either a nonmutagenic glucuronide conjugate or a mutagenic metabolite of the compound. Relatively low doses of the chemical were detected, and it was possible to follow the excretion pattern of the compounds over the collection period.
Mutagenicity detection of in vivo nitrosation of dimethylamine by nitrite
Authors: Whong Wen‐Zong , Speciner Norman D. , Edwards Gordon S. 
Published: February 2007

AbstractIn vivo nitrosation of dimethylamine by nitrite was measured with an intrahepatic host‐mediated mutagenicity assay using Salmonella typhimurium as the detecting organism. It was possible to detect the product, N‐nitrosodimethylamine, at much lower doses with this system than with previously reported in vivo systems. This and other improvements made it possible to detect the formation of nitrosodimethylamine from relatively low levels of gavaged precursors.
Mutagenicity of organic extracts from canadian drinking water in the salmonella/mammalian‐microsome assay
Authors: Nestmann Earle R. , Lebel Guy L. , Williams David T. , Kowbel David J. 
Published: February 2007

AbstractOrganic extracts of chlorinated Ontario drinking water samples have been found to induce mutation and lethality in the Salmonella/mammalian‐microsome histadine reversion assay. Collections of water were made at water treatment plants in five municipalities in June 1978. To determine the reproducibility of the positive mutagenic effects found, a second sampling at the same plants was performed in September 1978. Preparation of extracts involved passing 200 liter samples through XAD‐2 resin columns which were eluted with a mixture of hexane and acetone, and the eluent was evaporated to dryness. For those extracts with sufficient organic matter, dose‐related increases in mutagenicity were observed. Extracts of untreated water from a river and a well were weakly mutagenic.
Prevention of the mutagenic activation of an antischistosomal isothiocyanate in primates by an antibiotic
Authors: Batzinger Robert P. , Bueding Ernest , Crawford Karen , Bruce John 
Published: February 2007

AbstractAdministration of 4 nitro‐4′ isothiocyano‐diphenylamine (CGP 4540, amoscanate) to two nonhuman primates, Macaca mulatta and Cebus apella, resulted in the appearance of mutagenic material in the urines of these animals. Mutagenic metabolites of this drug could also be detected in the urines when the drug was administered to primates infected with Schistosoma mansoni and Schistosoma japonicum. As observed previously in mice, the mutagenic activation of amoscanate can be prevented in primates by coadministration of a single oral dose of erythromycin with no concomitant reduction in antischistosomal activity. The protective effect of erythromycin was confirmed in several crossover experiments. This dissociation of mutagenic from chemotherapeutic effects provides an opportunity to reduce serious potential long‐term risks of this anti‐schistosomal drug.
Genetic effects of strong magnetic fields in drosophila melanogaster: I. Homogeneous fields ranging from 13,000 to 37,000 gauss
Authors: Kale P. G. , Baum J. W. 
Published: February 2007

AbstractDrosophila melanogaster males were exposed to homogeneous magnetic fields of intensities of 13,000 to 37,000 Gauss as eggs, larvae, pupae and as adults. Sex linked recessive lethals were scored in chromosomes exposed as spermatozoa, spermatids and as spermatocytes. There was no indication of enhanced mutation induction by the magnetic fields.
In vitro mutagenicity and cell transformation screening of caprolactam
Authors: Greene Elliott J. , Friedman Marvin A. , Sherrod Julie A. 
Published: February 2007

AbstractCaprolactam was tested for genetic activity in bacterial and mammalian screens. It was inactive in the following tests: a) Salmonella/microsome mutagenicity; b) Chinese hamster ovary cell mutagenicity (induction of 6‐thioguanine mutants); c) Enhancement of SA7 virus transformation of primary hamster embryo cells, when administered before or after virus, and; d) Chemical transformation of secondary hamster embryo cells.
Tissue‐specific induction of sister chromatid exchanges by ethyl carbamate in mice
Authors: Roberts Gladwin T. , Allen James W. 
Published: February 2007

AbstractSister chromatid exchange (SCE) techniques were used to analyze the genetic effects of ethyl carbamate (urethane) in cultured mouse‐bone marrow cells, and in several different mouse tissues in vivo. Ethyl carbamate concentrations up to 5.0 mg/ml were ineffective in causing a significant elevation of SCE in vitro. After in vivo drug administration, bone marrow, liver and spermatogonial cells all revealed significant dose‐related increases in SCE. Baseline and relative incremental levels of SCE were somatic vs germ tissue‐specific. Regenerating liver cells exhibited significantly greater absolute SCE values than all other tissues examined. Marrow cells revealed intermediate values, while germ cells were the least sensitive in SCE responsiveness. Spermatogonia required a fourfold higher dose, over that effective in somatic tissues, to promote an approximate doubling of the baseline SCE level.In vivo SCE analysis affords sensitive risk assessments for different tissues. Thus, this approach should be generally useful for studying compounds with questionable mutagenic potential, and/or those exerting target organ specificities of related biological activity (eg, toxicity, carcinogenesis).