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410 results on '"Neugebauer, W."'

55. Relationship between apoptosis and the cell cycle in lymphocytes: roles of protein kinase C, tyrosine phosphorylation, and AP1

Author

J LeBlanc, J Kwast-Welfeld, Marianna Sikorska, Neugebauer W, H. Gourdeau, and P R Walker

Subjects
Programmed cell death, T-Lymphocytes, Adaptor Protein Complex 1, Molecular Sequence Data, Apoptosis, Protein tyrosine phosphatase, Biology, Receptor tyrosine kinase, Dexamethasone, Cell Line, chemistry.chemical_compound, Mice, Adaptor Protein Complex alpha Subunits, Phorbol Esters, Animals, Phosphorylation, Protein kinase C, Protein Kinase C, Base Sequence, Cell Cycle, JAK-STAT signaling pathway, Genes, fos, Proteins, Tyrosine phosphorylation, Cell Differentiation, Cell Biology, Cell cycle, Protein-Tyrosine Kinases, Enzyme Activation, Adaptor Proteins, Vesicular Transport, chemistry, Protein Biosynthesis, biology.protein, Cancer research, Interleukin-2, Tyrosine, Tyrosine kinase, Proto-Oncogene Proteins c-fos
Abstract

The mechanism of switching between the cell cycle and active cell death (apoptosis) was investigated in cytokine-dependent CTLL cells. These cells proliferate in the presence of interleukin 2 (IL2), but accumulate in early G1 and undergo apoptosis in its absence. In the absence of IL2 the cells also become sensitive to glucocorticoid-induced apoptosis. Using specific inhibitors of protein kinase C and tyrosine kinases we established that two signals are required to fully repress cell death and stimulate G1 progression. One of these signals activates protein kinase C (PKC) which represses cell death and the other activates a tyrosine kinase which confers glucocorticoid resistance and permits cell cycle progression. Thus, phorbol esters can activate PKC and maintain cell viability in the absence of IL2, but the cells cannot proliferate. Moreover, the cells remain sensitive to glucocorticoid-induced apoptosis unless the tyrosine kinase-mediated signal is also given. There is a correlation between the presence of AP1 DNA-binding activity and the repression of the cell death pathway. The c-jun gene is expressed constitutively and both IL2 and phorbol esters induce the expression of c-fos to generate a functional AP1 capable of repressing cell death. However, only interleukin 2 can initiate the tyrosine kinase-mediated modification that confers dexamethasone resistance and permits G1 progression. In the absence of IL2 glucocorticoids stimulate AP1 degradation and induce apoptosis.

Published
1993

59. A ten-stage electrostatic depressed collector for improving klystron efficiency.

Author

Neugebauer, W and Mihran, T. G

Subjects
Electronic Equipment
Abstract

A ten-stage electrostatic depressed collector, designed with the aid of an analog computer, was tested on a 1-kW CW 750-MHz klystron. Excellent correlation was achieved between computed and measured performance under varying conditions of RF drive. At full RF power output approximately 60 per cent of the spent beam energy was recovered by use of the depressed collector. The net power conversion efficiency of the tube was raised from its undepressed value of 54.3 per cent to approximately 70.9 per cent. At one-half full power output, a collector efficiency of 70 per cent was measured. At zero RF power output collector efficiency was 80 per cent. To achieve these results it was necessary to install a small focusing coil between the final drift tube and the collector. No spurious oscillations or instabilities were detected when collector depression was employed, nor was electron backstreaming increased significantly. Intentional short circuiting of adjacent collector electrode pairs was shown to cause only minor degradation in collector performance.

Published
1972

64. Angular magnetic field beam improves efficiency in klystrons and traveling wave tubes

Author

Neugebauer, W

Subjects
Physical Sciences
Abstract

Special lens shaping allows variation of focusing strength with radius. Lens can be either converging or diverging depending on charge of particles and direction of angular magnetic field. There is potential use for lens in particle analyzers, electron beam welding systems, microwave tube refocusing systems, and possible display type devices.

Published
1973

65. Refocusing of the spent axisymmetric beam in klystron tubes

Author

Branch, G. M and Neugebauer, W

Subjects
Electronic Equipment
Abstract

Analytic methods were developed and employed to optimize the magnetic field transition region between the output interaction gap of a klystron and a multi-stage depressed potential electrostatic beam collector, in order to enhance the power conversion efficiency of satellite-borne broadcast transmitters. Permanent magnet structures were designed to provide the magnetic field distributions required to expand and recollimate the spent electron beam of the power amplifier klystron for proper entry into the beam collector. These design criteria for magnetic field distributions for expanding and recollimating spent-beam electrons for optimal entry into a multi-stage depressed potential collector are generally applicable to traveling-wave tubes as well as klystrons.

Published
1972

68. Parathyroid Hormone Domain for Protein Kinase C Stimulation Located Within Amphiphilic Helix

Author

NATIONAL RESEARCH COUNCIL OF CANADA OTTAWA (ONTARIO), Gordon, H., Neugebauer, W., Rixon, R., Somorjai, R., Sung, W., NATIONAL RESEARCH COUNCIL OF CANADA OTTAWA (ONTARIO), Gordon, H., Neugebauer, W., Rixon, R., Somorjai, R., and Sung, W.

Abstract

This article is from 'Peptides. Chemistry and Biology: Proceedings of the American Peptide Symposium (12th) Held in Cambridge, Massachusetts on 16-21 June 1991', AD-A256 113, p37-39.

Published
1992

92. Berufliche Risikofaktoren des Harnblasenkarzinoms. Eine Fallkontrollstudie.

Author

Golka, K., Bandel, T., Reckwitz, T., Urfer, W., Bolt, H. M., Bremicker, K.-D., Neugebauer, W., and Schulze, H.

Abstract

Copyright of Der Urologe A is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Published
1999
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