Nitrous oxide (N2O) oxidizes vitamin B12. disrupting deoxyribonucleic acid (DNA) synthesis. Occupational exposures to subanesthetic levels of the gas have been documented that may result in suppressed proliferative cell activities. Male CD-I mice were exposed to 0, 50, 500, and 5000 parts of N2O per million parts of air (ppm) for 6 hr/day, 5 days/week for 2 and 13 weeks. Splenic lymphocytes were assayed for responsiveness to mitogens and for the ability to produce interleukin-2 (lL-2) . Tritiated-thymidine ([3H]-TdR) uptake was measured in CD-I splenic lymphocytes cultured in a mixed-lymphocyte culture (MLC). Cytolytic cell activity was measured by 51chromium release assay. Antibody-mediated immunocompetency was determined for sheep red blood cell (SRBC)-sensitized animals by plaque-forming cell (PFC) assay and sera anti-SRBC antibody titer. Deoxyuridine suppression tests (dUdRST) were performed on bone marrow cells. Serum adrenocorticotropic hormone and corticosterone levels were determined. There was significantly decreased splenic lymphocyte uptake of [3H)-TdR by cells cultured with mitogenic substances and in MLC following 2-week animal exposures to 5000 ppm. After 13-week exposures, the animals' splenic lymphocytes showed decreased [3H]-TdR uptake following low N20 dosing and nonsignificantly increased responsiveness at the higher gas exposures in both the blastogenic and MLC assays. Compared to control animals, the 5000- ppm-exposure group had significantly depressed PFC activity and circulating anti-SRBC immunoglobulin M levels following 13-week gas exposures, and all three subchronic exposure groups demonstrated both decreased liver weights and leukopenia. Bone marrow activity at these dosing levels was dose-responsively depressed following subchronic gas exposures.No hormonal effect appears to be attributable to N20 exposure.

Seit Anfang des 20. Jahrhunderts ist die Krankheit Krebs die zweithäufigste Todesursache. Die immer besser werdende Diagnostik zur Früherkennung von Krebserkrankungen bringt zudem mit sich, dass eine steigende Anzahl an Krankheitsfällen bekannt wird; gleichzeitig hat eine sichere Erkennung im Frühstadium einen hohen Stellenwert, da nur so frühzeitig therapeutische Maßnahmen ergriffen werden können. Obwohl zur kurativen oder zur palliativen Behandlung schon lange viele ausgereifte Therapiemethoden und -konzepte erfolgreich angewendet werden, sind bis heute viele Krebserkrankungen noch immer unheilbar und es gibt bislang in vielen Fällen noch keine potenten Arzneistoffe für eine wirkungsvolle Therapie. Die Suche nach neuen Wirkstoffen ist daher ein Schwerpunkt aktueller Forschung. Auch unsere Arbeitsgruppe beschäftigt sich mit dieser Thematik und hat in Zusammenarbeit mit dem Universitätsklinikum Würzburg ein neuartiges Pro-Prodrug- Konzept für antitumorale Wirkstoffe entwickelt. Daher war es ein Ziel der vorliegenden Arbeit, aufbauend auf medizinischen und biochemischen Vorarbeiten, eine Leitstruktur für antitumorale Wirkstoffe zu erarbeiten, die auf dem hier vorgestellten Pro-Prodrug-Konzept basiert, und eine entsprechende Syntheseroute zur Gewinnung erster Fluoreszenz-markierter Pro-Prodrug-Modellverbindungen zu etablieren. Eine andere interessante Substanzklasse, die nicht nur aufgrund ihrer Wirkeigenschaften als Photosensibilisatoren in der photodynamischen Therapie bereits Gegenstand intensiver Forschung ist, sondern auch in weiteren Bereichen der angewandten Chemie, wie beispielsweise in der metallorganischen Katalyse oder in den Materialwissenschaften Anwendung findet, sind die Porphyrine. Neben den achiralen Vertretern finden die chiralen Porphyrinoide Anwendung in der chiralen Erkennung oder in der asymmetrischen Synthese. Auf dem Gebiet der Porphyrine war das Ziel der vorliegenden Arbeit die gezielte Synthese N,C- und C,C-verknüpfter dimerer und trimerer Porphyrine, einhergehend mit intensiven Untersuchungen der Reaktivität der verwendeten Bausteine, des Reaktionsmechanismus und der hohen Regioselektivität. Da einige der synthetisierten Substanzen Axial- oder Helikalchiralität aufweisen, wurden diese durch HPLC-CD eingehend auf ihre chiroptischen Eigenschaften untersucht. / Since the beginning of the 20th century cancer has been the second most common cause of death. Due to the continuously improving diagnosis for the early detection of cancer the number of cases that becomes apparent, rises, but coincidently a clear identificaton in the early stage is very important to start with the adequate therapy timely. Although various well established therapy methods and concepts for the curative or the palliative treatment have been existed for a long time, many cancer deseases, are still incurable and there are no potential drugs for a therapy, so far. Hence, the identification of novel drugs and active agents is a major current research task. Our research group is also involved with this topic and in cooperation with the University Hospitel of Würzburg a novel pro-prodrug concept for antitumoral drugs was developed. Thus, one aim of the present work was, based on previous medical and biochemical work, to develop a lead structure for antitumoral drugs using the pro-prodrug concept described herein and to establish a synthetic route to first fluorescence-labelled pro-prodrug model compounds. Another interesting class of compounds that is not only a current subject of intensive research because of its properties as photosensitizers in the photodynamic therapy, but also plays a crucial role in modern applied chemistry, e.g., in metalorganic catalysis or in the field of material science, are the porphyrins. Besides the achiral representatives, the chiral porphyrinoids are used for chiral recognition or in asymmetric synthesis. In the field of porphyrins the aim of the present work was the directed synthesis of N,C- and C,C-linked dimeric und trimeric porphyrins, together with intensive investigations on the reactivity of the used building blocks, on the reaction mechanism and on the high regioselectivity. Some of the synthesized compounds are axially or helically chiral, therefore, HPLC-CD measurements were carried out to investigate their chiroptical features.

The thesis describes the development during the 1990s of visual artists' utilisation of computer-based interactive multimedia and the production internationally, with a focus on Australian artists, of artworks on the CD-ROM media format. Earlier parts of the author's research led to the exhibition, 'Burning the Interface &lt International Artists' CD-ROM&gt', which he co-curated, opening at the Museum of Contemporary Art, Sydney, in 1996, before touring to Perth, Brisbane, Melbourne and Adelaide. The thesis surveys the range of practice by artists working with digital media and the opportunities for exhibition in the public spaces of museums, galleries and the street, and advances scenarios for correcting the laxity of response by the exhibiting institutions to the vigour with which Australian artists represented their work and ideas at this time in national and international forums. Four published artists' work on CDROM are analysed in detail, and a concluding chapter about 'interactive multimedia' and its usefulness as an art medium to the artist introduces the studio practice component of this MFA submission. This takes the form of a prototype 'experimental' version of an interactive multimedia work on CD-ROM, ('Strangers on the Land') a copy of which is contained in a pocket at the rear of the bound version.

Depuis 1990, l'édition de CDroms d'auteur a marqué l'édition numérique. Ce travail vise à interroger les conditions de réception esthétique de ces formes éditoriales. L'étude critique de cinq titres est précédée d'un panorama de ces publications. Deux principes sont privilégiés : le jeu des actions et la construction narrative, car ils en déterminent les modes de réception. Perçus comme antagonistes malgré leurs similitudes, le jeu et le récit sont l'objet d'une réflexion théorique. Celle-ci distingue jeu-game et jeu-play et insiste sur l'importance d'un niveau racontable, précédant le récit verbal. Ces distinctions permettent une articulation plus riche que l'opposition temporelle initiale entre jeu et récit qui semblait tout d'abord caractériser la réception esthétique de ces éditions. De nouvelles critiques de CDroms s'appuient sur ces distinctions, elles insistent sur l'invitation préalable induite par l'objet, la conduite des expériences engagées et les conditions de leur clôture.

<p>Using a conditioning paradigm and an automated olfactometer, I investigated the olfactory sensitivity of five CD-1 mice for seven aromatic aldehydes. With two of the stimuli (3-phenylpropanal and canthoxal), the animals discriminated concentrations as low as 10 ppb (parts per billion) from the odorless solvent and with four of the stimuli (helional, cyclamal, lilial and lyral) they discriminated concentrations as low as 1 ppb, with single individuals even scoring better. All five animals yielded the by far lowest threshold value with bourgeonal and discriminated a concentration of 0.1 ppq (parts per quadrillion) from the odorless solvent. The detection threshold values for aromatic aldehydes were found to be affected by the type of functional groups and oxygen moiety attached to the benzene ring. A comparison of the present data with those obtained in other species found no clear correlation between olfactory sensitivity and the size of the olfactory receptor repertoire.</p>

<p>Under en kurs om människans fysiologi letade jag användbara hemsidor på Internet. Jag slogs då av att det fanns många bra hemsidor på engelska, men knappt några på svenska. Jag bestämde mig då för att göra en svensk sida som är användbar för skolbruk. Då datorer och Internet mest används för faktasökande i samband med eget arbete ville jag bygga upp något annorlunda. </p><p>Meningen med detta arbete är att försöka bygga upp ett interaktivt läromedel med program som går att hitta gratis på Internet, samt att undersöka vilka problem som kan uppstå vid framställningen. Min förhoppning är att detta arbete kan bidra till att ge lärare en ny uppfattning om Internets möjligheter. Då sidorna är uppbyggda i HTML fungerar de på alla datorer med webläsare. Genom att koppla kemin till elevernas vardag kan man visa att kemin inte bara är ett skolämne, utan något som omger oss och styr våra liv. Detta arbete kan användas både i skolan och i hemmet, eftersom experimenten är anpassade för att göras hemma.</p><p>"Vardagskemi"är uppbyggt kring ett hus där man kan"vandra"runt. Inne i de olika rummen finns skåp som man kan öppna. Klickar man sedan på de olika varorna i skåpet kommer man vidare till en faktasida, där varan beskrivs ingående. CD-skivan innehåller fakta om c.a. 30 hushållsvaror, 60 kategoriserade experiment som kan göras hemma, samt länkar till intressanta hemsidor.</p>

<p>The ability to create surfaces with well-defined chemical properties is a major research field. One possibility to do this is to design peptides that bind with a specific secondary structure to silica nanoparticles. The peptides discussed in this thesis are constructed to be random coil in solution, but are “forced” to become helical when adsorbed to the particles. The positively charged side-chains on the peptides strongly disfavor an ordered structure in solution due to electrostatic repulsion. When the peptides are introduced to the particles these charges will strongly favor the structure because of ion pair bonding between the peptide and the negatively charged nanoparticles. The peptide-nanoparticle system has been thoroughly investigated by systematic variations of the side-chains. In order to determine which factors that contributes to the induced structure, several peptides with different amino acid sequences have been synthesized. Factors that have been investigated include 1) the positive charge density, 2) distribution of positive charges, 3) negative charge density, 4) increasing hydrophobicity, 5) peptide length, and 6) by incorporating amino acids with different helix propensities. Moreover, pH dependence and the effect of different nanoparticle curvature have also been investigated. It will also be shown that the system can be modified to incorporate a catalytic site that is only active when the helix is formed. This research will increase our understanding of peptide-surface interactions and might be of importance for both nanotechnology and medicine.</p>

The primary question to be answered as a result of the research was: Do native English-speaking undergraduate students learn CD-ROM database search skills more effectively through the use of conventional instruction method or by training confined to a written manual self-instructional method? Thirty-seven Oregon State University students were randomly assigned to two groups and participated in the study. The study utilized an experimental pretest-posttest control group design. The length of the study was six weeks. All participants were pre and post-measured using the CD-ROM Database Competency Test which was validated using the Delphi method. The subjects were trained using Wilsondisc and SilverPlatter databases. ANCOVA and t-tests were the main statistics utilized in the analysis. The results of the study were as follows: 1) Subjects in both treatment groups experienced significant test score gains between pretest and posttest; 2) Those subjects which were assigned to the conventional instruction group had significantly higher scores than did subjects assigned to the self-instruction group; 3) Subject gender was determined not to be a factor when differences were considered from test results; 4) Interaction did not play a significant role in influencing the data results; 5) Students rated formal training as being very helpful in improving the effectiveness of their CD-ROM database searches. The major conclusion drawn from the study was that the native English-speaking students at Oregon State University learned CD-ROM searching skills more effectively through the conventional instruction method than those students who were trained by self-instruction. The results of the study substantiated the need to undertake further efforts to improve the efficiency of learning CD-ROM access instructional methods in higher educational settings. / Graduation date: 1994

<p>Concept Development and Experimentation (CD & E) är en utvecklingsmetod som idag inryms inom FM. Idén är att den skall bidra med ett metodiskt arbetssätt för framtida utveckling av organisationen. Ambitionen är att tillämpa metoden inom olika delar av hela FM utvecklingsprocess. När CD & E lanseras som det nya sättet att bedriva utvecklingsarbete infinner sig frågan: - Hur har vi historiskt utvecklat förmågor och i vilken mån tar CD & E hand om tidigare erfarenheter från genomförda organisations- och metodförsök (OMF)? Finns det en spänning mellan CD & E och tidigare arbeten med OMF, eller stödjer de olika delar av utvecklingen? Denna uppsats beskriver hur OMF och CD & E kan komplettera varandra och bidra till FM förmågeutveckling.</p>

The ability to create surfaces with well-defined chemical properties is a major research field. One possibility to do this is to design peptides that bind with a specific secondary structure to silica nanoparticles. The peptides discussed in this thesis are constructed to be random coil in solution, but are “forced” to become helical when adsorbed to the particles. The positively charged side-chains on the peptides strongly disfavor an ordered structure in solution due to electrostatic repulsion. When the peptides are introduced to the particles these charges will strongly favor the structure because of ion pair bonding between the peptide and the negatively charged nanoparticles. The peptide-nanoparticle system has been thoroughly investigated by systematic variations of the side-chains. In order to determine which factors that contributes to the induced structure, several peptides with different amino acid sequences have been synthesized. Factors that have been investigated include 1) the positive charge density, 2) distribution of positive charges, 3) negative charge density, 4) increasing hydrophobicity, 5) peptide length, and 6) by incorporating amino acids with different helix propensities. Moreover, pH dependence and the effect of different nanoparticle curvature have also been investigated. It will also be shown that the system can be modified to incorporate a catalytic site that is only active when the helix is formed. This research will increase our understanding of peptide-surface interactions and might be of importance for both nanotechnology and medicine.