Showing papers by "Bielefeld University published in 1994"

A chimeric transactivator allows tetracycline-responsive gene expression in whole plants

Abstract: Summary The chimeric transcriptional activator tTA, a fusion between the Tn 10 encoded Tet repressor and the activation domain of the Herpes simplex virion protein VP16, was stably expressed in transgenic tobacco plants. It stimulates transcription of the β-glucuronidase (gus) gene from an artificial promoter consisting of 7 tet operators and a TATA-box. Tetracycline, which Interferes with binding of tTA to operator DNA, reduces gus expression over several orders of magnitude. This stringency of regulation suggests that the system can be used to construct transgenic plants encoding a potentially lethal gene product. Furthermore, the specific and fast inactivation of tTA allows study of the stability of RNAs and proteins.

Soziale Hilfe als Funktionssystem der Gesellschaft

Abstract: Zusammenfassung Soziale Arbeit und soziale Hilfe unterliegen in der modernen Gesellschaft einem Motiv-, einem Stigmatisierungs- und einem Effizienzverdacht. Solange sich die theoretische Reflexion von Sozialarbeit und Sozialhilfe an der Leitdifferenz von Konformität und Devianz orientiert, kann diesen Verdachtsmomenten weder theoretisch noch praktisch begegnet werden. Der Beitrag macht daher den Vorschlag, die bisher nur als „tragic choice“ mitgeführte, also ausgeblendete Option der Nichthilfe mit der Möglichkeit der Hilfe zusammenzusehen und beide Möglichkeiten als die beiden Seiten einer Differenz zu betrachten, die von einem Teilsystem der Gesellschaft eingeführt, durchgesetzt und betreut wird. Anhand der Begriffe Funktion, operationale Geschlossenheit und Codierung wird die Hypothese geprüft, daß sich in der modernen Gesellschaft ein Funktionssystem der Sozialhilfe ausdifferenziert hat, das mittels des Codes von Helfen versus Nichthelfen Defizite kompensiert und in der Gesellschaft und stellvertretend für die Gesellschaft Inklusionsprobleme der Bevölkerung betreut. Wenn sich diese Hypothese aufrechterhalten läßt, gewinnt man daraus Vorteile einer Differenzierung zwischen dem Funktionssystem auf der einen Seite, das die beiden Werte des Codes gleichwertig, also als unentscheidbar, behandelt, und Organisationen auf der anderen Seite, die auf der Ebene der Einführung dritter und vierter Werte Programme testen und anwenden, die entscheidbar machen, wann geholfen und wann nichtgeholfen wird. Die Einführung der Funktionssystemperspektive führt ferner dazu, für alle Arten helfender Intervention eine Systemreferenz anzugeben, die diejenige des intervenierenden Systems selber ist. Der Erfolg der Intervention ist Zufall, und nur deswegen ist das System freigestellt, seine eigenen Operationen autonom zu konditionieren.

Susceptibilities, the specific heat, and a cumulant in two-flavor QCD.

Abstract: We study the quark mass dependence of various response functions, which contribute to chiral susceptibilities and the specific heat in the staggered fermion formulation of two-flavor QCD. This yields information about the critical exponents \ensuremath{\alpha}, \ensuremath{\beta}, and \ensuremath{\delta}. In the case of the chiral susceptibility, obtained as a derivative of the chiral order parameter with respect to the quark mass, we calculate all contributions. This allows us to construct a cumulant of the order parameter, which is a scaling function and yields a direct determination of the critical exponent \ensuremath{\delta}. All our results are consistent with a second order phase transition.

Society as a laboratory: the social risks of experimental research

Abstract: Professor Wolfgang Krohn and Priv-Doz Dr Johannes Weyer are in the Fakultat fur Soziologie, Universitat Bielefeld, Universitatsstrasse 25, D-33615 Bielefeld, Germany. This paper was written in connection with several research projects in which 'experimental implementations' of various kinds were studied (see Herbold, Krohn and Weyer, 1991; Herbold, Krohn and Weyer, 1992; Asdonk, Bredeweg and Kowol, 1991; and Weyer, 1994). IN M O D E R N SCIENCE, there is an increasing tendency to extend research processes and their related risks beyond the limits of the laboratory or other such institution, and directly into the wider society. To greater or lesser extents, these moves are experiments. This tendency is apparent in, for instance, nuclear energy technologies, some developments in ecology, the use of physiologically dangerous chemicals, the introduction of some medicines, and in some military technology. A common denominator in such cases is that they cannot be legitimised in the name of research alone. In keeping with at least the German way of viewing them, they are declared to be the 'implementation of verified knowledge', and are justified on the basis of non-scientific (for instance commercial) interests. With the increased rate of technological innovation in recent decades, the implementation of verified knowledge has frequently become (nolens volens) the testing of risk-involving technologies. For want of a better term, we will refer to these processes as 'experimental implementation(s)', 'real-life experiments' or 'implicit experiments'. The 'risks' of interest here are related to safety, not to (for instance) the probability of obtaining publishable scientific results or of making profits. These terms have been chosen to suggest that the introduction of new technologies frequently reveals features of the traditional laboratory experimental generation of knowledge. Indeed, this is often deliberately built into the design of the project. Real-life experiments, however, differ fundamentally in one aspect from traditional ex-

Neutrophil collagenase (MMP-8) cleaves at the aggrecanase site E373-A374 in the interglobular domain of cartilage aggrecan

Abstract: Native and recombinant neutrophil collagenase (MMP-8) was shown to cleave at the E373-A374 'aggrecanase' site in the interglobular domain of aggrecan. The time course of digestion in vitro showed that MMP-8 cleaved initially at N341-F342, the predominant metalloproteinase site, before cleaving at the E373-A374 site. A synthetic peptide, IPENFFG, inhibited cleavage at E373-A374 but not N341-F342 in vitro, indicating that the E373-A374 sequence was a less preferred site for MMP-8 cleavage than N341-F342. IPENFFG also inhibited release of A374 RGSVI fragments from cartilage in explant culture, suggesting that a metalloproteinase cleaved at the aggrecanase site in situ. The possibility remains that 'aggrecanase' may be a metalloproteinase in cartilage.

Control of human arm movements in two dimensions: paths and joint control in avoiding simple linear obstacles

Abstract: In order to examine path planning and the control of redundant degrees of freedom in the human arm, the movements of the shoulder, elbow and wrist were recorded as subjects moved a pointer to a target and avoided a simple obstacle. With respect to joint control, the results show that the extra degree of freedom provided by the wrist is incorporated into target movements in a systematic manner for both large and small obstacles; it is not used only when there is no geometrical alternative. For the wrist, two strategies are apparent, depending upon the length of the obstacle. Wrist extension predominates for shorter obstacles, while flexion or extension and flexion predominate for longer obstacles. These wrist movements shorten the effective length of the distal segments (lower arm plus hand and pointer) and thus reduce the excursion required at the proximal joints. In part, they correspond to assuming the most comfortable arm configuration at each point in the new path necessitated by the obstacle and can be described by static cost functions. However, wrist extension is also used to move the hand and pointer away from the obstacle as shoulder and elbow movements carry the wrist itself towards the obstacle. Wrist flexion is also used to move the pointer tip rapidly past the obstacle. These components, which cannot be explained by static cost functions alone, confirm for the human arm the hypothesized use of redundant degrees of freedom in obstacle avoidance. With respect to path planning, the results show that the minimum distance between pointer and obstacle remains fairly constant over a large range of obstacle lengths; this relative invariance is interpreted to support the hypothesis that workspace coordinates are important for movement planning. However, minimum distance and several other path parameters do depend significantly on the orientation and location of the movement in the workspace. This inhomogeneity implies that movement planning does not occur exclusively in workspace coordinates; it suggests an influence of joint space criteria. In frontal movements, for example, the systematic decline in the minimum distance with increasing obstacle length is interpreted as a compromise reducing the amount of extra joint movement and the discomfort of arm configurations.

New Perspectives in Polyoxometalate Chemistry by isolation of compounds containing very large moieties as transferable building blocks: (NMe4)5[As2Mo8V4AsO40] · 3H2O, (NH4)21[H3Mo57V6(NO)6O183(H2O)18] · 65 H2O, (NH2Me2)18(NH4)6[Mo57V6(NO)6O183(H2O)18] · 14 H2O, and (NH4)12[Mo36(NO)4O108(H2O)16] · 33 H2O

Abstract: The compounds (NMe4)5[As2Mo8V4AsO40] . 3 H2O 2a, (NH4)21[H3Mo57V6(NO)6O183(H2O)18] . 65 H2O 3a, (NH2Me2)18(NH4)6[Mo57V6(NO)6O183(H2O)18] . 14 H2O 3b and (NH4)12[Mo36(NO)4O108(H2O)16] . 33 H2O 4a (3a and 4a were not correctly reported in the literature regarding to their composition, structures and the oxidation states of the metal centres) which contain large isolated anionic species, have been prepared (among them 3 a, 3 b, and 4 a in rather high yield) and characterized by complete crystal structure analysis as well as IR/Raman, UV/VIS/NIR, ESR spectroscopy and magnetic susceptibility measurements, redox titrations, bond valence sum calculations, elemental analyses and thermogravimetric studies. Perspectives for polyoxometalate chemistry referring to the synthesis of ''extremely'' large nanoscaled species are discussed, together with the occurrence of a large transferable {Mo17} building block in the compounds 3a, 3b and 4a which also exists in the corresponding iron compound Na3(NH4)12[H15Mo57Fe6(NO)6O183(H2O)18] . 76H2O 7a.

Effective Lagrangians with higher derivatives and equations of motion

Abstract: The problems that are connected with Lagrangians which depend on higher derivatives (namely, additional degrees of freedom, unbound energy from below, etc.) are absent if effective Lagrangians are considered because the equations of motion may be used to eliminate all higher time derivatives from the effective interaction term. The application of the equations of motion can be realized by making field transformations that involve derivatives of the fields. Using the Hamiltonian formalism for higher-order Lagrangians (Ostrogradsky formalism), Lagrangians that are related by such transformations are shown to be physically equivalent (at the classical and at the quantum level). The equivalence of Hamiltonian and Lagrangian path integral quantization (Matthews's theorem) is proven for effective higher-order Lagrangians. Effective interactions of massive vector fields involving higher derivatives are examined within gauge noninvariant models as well as within (linearly or non-linearly realized) spontaneously broken gauge theories. The Stueckelberg formalism, which relates gauge noninvariant to gauge invariant Lagrangians, becomes reformulated within the Ostrogradsky formalism.

Intersegmental and local interneurons in the metathorax of the stick insect Carausius morosus that monitor middle leg position.

Abstract: 1. In the stick insect, proprioceptive information from the middle leg is used to define the target for the swing movement of the adjacent rear leg ("targeting behavior"). To investigate the underl...

Transforming Growth Factor β1 Regulates Tissue Inhibitor of Metalloproteinases—1 Expression in Differentiated Human Articular Chondrocytes

Abstract: Objective. To investigate the role of interleukin-6 (IL-6) and transforming growth factor beta 1 (TGF beta 1) in the regulation of tissue inhibitor of metalloproteinases-1 (TIMP-1) synthesis in human articular chondrocytes. Methods. Articular cartilage was obtained from human knee joints 24 hours after death. Chondrocytes were isolated by collagenase digestion and embedded in low-gelling-temperature agarose. After stimulation by cytokines, total RNA was isolated and analyzed by Northern blotting. TIMP-1 protein levels were determined using a competitive enzyme-linked immunosorbent assay. Results. Human chondrocytes in agarose culture expressed messenger RNA (mRNA) for the IL-6 receptor (gp80) and its signal-transducing subunit gp130. In contrast to the findings in a previous study, IL-6 did not stimulate TIMP-1 expression in these cells, whereas TGF beta 1 was an important inducer of TIMP-1 mRNA and protein synthesis. Conclusion. Our findings suggest that TGF beta 1 has a protective effect on the extracellular matrix of human articular chondrocytes.

The Metabolites of the Herbicide L-Phosphinothricin (Glufosinate) (Identification, Stability, and Mobility in Transgenic, Herbicide-Resistant, and Untransformed Plants).

Abstract: The metabolism of the herbicide L-phosphinothricin (L-Pt) was analyzed in tobacco (Nicotiana tabacum), alfalfa (Medicago sativa), and carrot (Daucus carota). In transgenic, Pt-resistant plants expressing the Pt-N-acetyltransferase gene (pat), L-Pt was acetylated, resulting in two forms of N-acetyl-Pt (ac-Pt). In transgenic plants expressing only low pat-encoded acetylating activity as well as in genetically unmodified plants, three metabolic compounds 4-methylphosphinico-2-oxo-butanoic acid, 3-methylphosphinico-propanoic acid (MPP), and 4-methylphosphinico-2-hydroxy-butanoic acid (MHB) were identified. Hence, the transgene-encoded acetylation of L-Pt competes with a plant-specific degradation. The compounds MPP, MHB, and ac-Pt were found to be the final, stable products of the plant's metabolic pathways. The mobility of these stable compounds in the plant was investigated: L-Pt as well as the derived metabolites were found to be preferentially transported to the upper regions of the plant.

Calculation of Feynman diagrams from their small momentum expansion

Abstract: A new powerful method to calculate Feynman diagrams is proposed. It consists in setting up a Taylor series expansion in the external momenta squared (in general multivariable). The Taylor coefficients are obtained from the original diagram by differentiation and putting the external momenta equal to zero, which means a great simplification. It is demonstrated that it is possible to obtain by analytic continuation of the original series high precision numerical values of the Feynman integrals in the whole cut plane. For this purpose conformal mapping and subsequent resummation by means of Pade approximants or Levin transformation are applied.

Identified nonspiking interneurons in leg reflexes and during walking in the stick insect

Abstract: In the stick insect Carausius morosus identified nonspiking interneurons (type E4) were investigated in the mesothoracic ganglion during intraand intersegmental reflexes and during searching and walking.