Partizipative Unterrichtsforschung: Erfahrungsbericht über ein Projekt zum Klassenrat

Der Beitrag berichtet über eine partizipativ angelegte Studie zu einem spezifischen Unterrichtsformat, dem Klassenrat. Eine wesentliche Zielsetzung der Studie besteht darin, dass sich die in das Projekt involvierten Lehrpersonen als Kooperationspartnerinnen und Kooperationspartner am Forschungsprozess beteiligen. Im Folgenden wird der partizipativ konzipierte Zugang zur Unterrichtsforschung vorgestellt und es wird über die Rahmenbedingungen, aber auch über die Konsequenzen dieses Vorgehens nachgedacht. Dabei wird Bezug genommen auf Überlegungen, wie sie in bestimmten Richtungen der Praxisforschung oder der angewandten Gesprächsforschung angestellt werden, und es werden die Erfahrungen mit partizipativer Unterrichtsforschung dargelegt

Syntheses and characterization of vitamin B12-Pt(II) conjugates and their adenosylation in an enzymatic assay

Aiming at the use of vitamin B12 as a drug delivery carrier for cytotoxic agents, we have reacted vitaminB12 with trans-[PtCl(NH3)2(H2O)]+, [PtCl3(NH3)]− and [PtCl4]2−. These Pt(II) precursors coordinated directly to the Co(III)-bound cyanide, giving the conjugates [{Co}-CN-{trans-PtCl(NH3)2}]+ (5), [{Co}-CN-{trans-PtCl2(NH3)}] (6), [{Co}-CN-{cis-PtCl2(NH3)}] (7) and [{Co}-CN-{PtCl3}]− (8) in good yields. Spectroscopic analyses for all compounds and X-ray structure elucidation for 5 and 7 confirmed their authenticity and the presence of the central "Co-CN-Pt” motif. Applicability of these heterodinuclear conjugates depends primarily on serum stability. Whereas 6 and 8 transmetallated rapidly to bovine serum albumin proteins, compounds 5 and 7 were reasonably stable. Around 20% of cyanocobalamin could be detected after 48h, while the remaining 80% was still the respective vitaminB12 conjugates. Release of the platinum complexes from vitaminB12 is driven by intracellular reduction of Co(III) to Co(II) to Co(I) and subsequent adenosylation by the adenosyltransferase CobA. Despite bearing a rather large metal complex on the β-axial position, the cobamides in 5 and 7 are recognized by the corrinoid adenosyltransferase enzyme that catalyzes the formation of the organometallic C-Co bond present in adenosylcobalamin after release of the Pt(II) complexes. Thus, vitamin B12 can potentially be used for delivering metal-containing compounds into cell

Selective Release of Technetium Complexes from a Solid Phase due to C–N Bond Cleavage upon Metal Coordination

A new method for 99mTc-labeling using solid-phase technology is described. It allows the separation of unlabeled from labeled bioactive molecules by simple filtration. The procedure is based on a site-specific C–N bond cleavage reaction initiated by the formation of [TcI(CO)3L]-complexes

Syntheses of Fluorescent Vitamin B12-Pt(II) Conjugates and their Pt(II) Release in a Spectroelectrochemical Assay

The cisplatin adduct of vitamin B12, cis-[PtCl(NH3)2B12]+ (1) reacts with dansyl-imidazole to form cis-[Pt(dansyl-imidazole)(NH3)2B12] (2). In a spectroelectrochemical assay, Co(III) in 2 was reduced to Co(II) under concomitant release of the Pt(II) complex. Since similar reduction occurs in the intracellular space, 2 can be used for studying cell uptake monitored by fluorescent microscopy. The insertion of a fluorescent marker into the platinum moiety will also facilitate the isolation of the platinum complex released from B12 and therefore to characterize its chemical authenticity

Participatory classroom research: Lessons learned in a project on class council

Der Beitrag berichtet über eine partizipativ angelegte Studie zu einem spezifischen Unterrichtsformat, dem Klassenrat. Eine wesentliche Zielsetzung der Studie besteht darin, dass sich die in das Projekt involvierten Lehrpersonen als Kooperationspartnerinnen und Kooperationspartner am Forschungsprozess beteiligen. Im Folgenden wird der partizipativ konzipierte Zugang zur Unterrichtsforschung vorgestellt und es wird über die Rahmenbedingungen, aber auch über die Konsequenzen dieses Vorgehens nachgedacht. Dabei wird Bezug genommen auf Überlegungen, wie sie in bestimmten Richtungen der Praxisforschung oder der angewandten Gesprächsforschung angestellt werden, und es werden die Erfahrungen mit partizipativer Unterrichtsforschung dargelegt. (DIPF/Orig.)This paper reflects on a participatory research project on a specific teaching format, namely the class council. A key objective of the study is to form a collaborative partnership with the teachers and to involve them in the research process. We present our participatory approach to classroom research and reflect on the conditions as well as on the consequences of our method. Moreover, we refer to concepts from the field of practical research and applied conversation analysis and report on our experiences with participatory classroom research

Metal-directed assembly of cyclometallopeptides

An undecapeptide predisposed to cyclisation as a result of the inclusion of a proline residue has been functionalised with tpy metal-binding domains at both the N and C termini, and shown to form a cyclometallopeptide upon reaction with iron(II) salts

Quantitative and Qualitative Approaches in Conversation Analysis: Methodological Reflections on a Study of Argumentative Group Discussions

This paper discusses fundamental and applied aspects of the relationship between qualitative and quantitative approaches in conversation analysis (CA). Starting from the observation that informal coding and informal quantification can be found in numerous works of classical CA, the paper discusses features of formal quantification. In the main section of the paper, such formal quantifications (based on conversation-analytic categories) are carried out on a corpus of 180 conversations of Swiss German schoolchildren, and the preceding elaboration of a coding scheme is discussed in detail. The data consist of discussions between elementary schoolchildren. The aim of the quantifications is to develop reliable statements about the relationship between interactive argumentative practices (modalization, perspectivation, argumentative complexity, interactivity) and other variables (age, setting, gender) and thus about crucial aspects of oral argumentation competence. In addition, we discuss various visualizations based on quantified data, which make individual differences between interactants particularly visible

Iodination of cisplatin adduct of Vitamin B-12 {B-12}-CN-{cis-PtCl(NH3)(2)}](+)

The cisplatin adduct of vitamin B-12, {B-12}-CN-{cis-PtCl(NH3)(2)}](+) (1), reacts with iodide in aqueous solution to form {B-12}-CN-{trans-PtI2(NH3)}] (3) in good yield. Mono-substitution of chloride was not observed since a subsequent replacement of one NH3 by a second iodide is very fast as compared to the Cl- -> I- exchange. The same reaction conditions allowed to introduce radioiodide I-131. Vitamin B-12 can therefore be labeled with radionuclides via binding to the Pt(II) center. (C) 2006 Elsevier B.V. All rights reserved