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Licht C, Weisser R, Metzger T, Schlögl C. P 68 Unintentional maladjustment of a shunt valve due to electromagnetic door locks – A case report. Clin Neurophysiol 2022. [DOI: 10.1016/j.clinph.2022.01.099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Houard A, Jukna V, Point G, André YB, Klingebiel S, Schultze M, Michel K, Metzger T, Mysyrowicz A. Study of filamentation with a high power high repetition rate ps laser at 1.03 µm. Opt Express 2016; 24:7437-7448. [PMID: 27137034 DOI: 10.1364/oe.24.007437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We study the propagation of intense, high repetition rate laser pulses of picosecond duration at 1.03 µm central wavelength through air. Evidence of filamentation is obtained from measurements of the beam profile as a function of distance, from photoemission imaging and from spatially resolved sonometric recordings. Good agreement is found with numerical simulations. Simulations reveal an important self shortening of the pulse duration, suggesting that laser pulses with few optical cycles could be obtained via double filamentation. An important lowering of the voltage required to induce guided electric discharges between charged electrodes is measured at high laser pulse repetition rate.
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Schneider W, Ryabov A, Lombosi C, Metzger T, Major Z, Fülöp JA, Baum P. 800-fs, 330-μJ pulses from a 100-W regenerative Yb:YAG thin-disk amplifier at 300 kHz and THz generation in LiNbO₃. Opt Lett 2014; 39:6604-7. [PMID: 25490632 DOI: 10.1364/ol.39.006604] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Yb:YAG thin-disk lasers offer extraordinary output power, but systems delivering femtosecond pulses at a repetition rate of hundreds of kilohertz are scarce, even though this regime is ideal for ultrafast electron diffraction, coincidence imaging, attosecond science, and terahertz (THz) spectroscopy. Here we describe a regenerative Yb:YAG amplifier based on thin-disk technology, producing 800-fs pulses at a repetition rate adjustable between 50 and 400 kHz. The key design elements are a short regenerative cavity and fast-switching Pockels cell. The average output power is 130 W before the compressor and 100 W after compression, which at 300 kHz corresponds to pulse energies of 430 and 330 μJ, respectively. This is sufficient for a wide range of nonlinear conversions and broadening/compression schemes. As a first application, we use optical rectification in LiNbO₃ to produce 30-nJ single-cycle THz pulses with 6 W pump power. The electric field exceeds 10 kV/cm at a central frequency of 0.3 THz, suitable for driving structural dynamics or controlling electron beams.
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Metzger T. Drying in the Process Industry. Von C. M. van't Land. CHEM-ING-TECH 2013. [DOI: 10.1002/cite.201390005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Jørgensen TN, Alfaro J, Enriquez HL, Jiang C, Loo WM, Atencio S, Bupp MRG, Mailloux CM, Metzger T, Flannery S, Rozzo SJ, Kotzin BL, Rosemblatt M, Bono MR, Erickson LD. Development of murine lupus involves the combined genetic contribution of the SLAM and FcgammaR intervals within the Nba2 autoimmune susceptibility locus. J Immunol 2009; 184:775-86. [PMID: 20018631 DOI: 10.4049/jimmunol.0901322] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Autoantibodies are of central importance in the pathogenesis of Ab-mediated autoimmune disorders. The murine lupus susceptibility locus Nba2 on chromosome 1 and the syntenic human locus are associated with a loss of immune tolerance that leads to antinuclear Ab production. To identify gene intervals within Nba2 that control the development of autoantibody-producing B cells and to determine the cellular components through which Nba2 genes accomplish this, we generated congenic mice expressing various Nba2 intervals where genes for the FcgammaR, SLAM, and IFN-inducible families are encoded. Analysis of congenic strains demonstrated that the FcgammaR and SLAM intervals independently controlled the severity of autoantibody production and renal disease, yet are both required for lupus susceptibility. Deregulated homeostasis of terminally differentiated B cells was found to be controlled by the FcgammaR interval where FcgammaRIIb-mediated apoptosis of germinal center B cells and plasma cells was impaired. Increased numbers of activated plasmacytoid dendritic cells that were distinctly CD19+ and promoted plasma cell differentiation via the proinflammatory cytokines IL-10 and IFNalpha were linked to the SLAM interval. These findings suggest that SLAM and FcgammaR intervals act cooperatively to influence the clinical course of disease through supporting the differentiation and survival of autoantibody-producing cells.
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Affiliation(s)
- Trine N Jørgensen
- Division of Allergy and Clinical Immunology, University of Colorado Health Sciences Center, Denver, CO 80262, USA
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Metzger T, Tsotsas E, Prat M. Porennetzwerkmodelle für die Trocknung. CHEM-ING-TECH 2007. [DOI: 10.1002/cite.200750287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Ishii N, Teisset CY, Köhler S, Serebryannikov EE, Fuji T, Metzger T, Krausz F, Baltuska A, Zheltikov AM. Widely tunable soliton frequency shifting of few-cycle laser pulses. Phys Rev E Stat Nonlin Soft Matter Phys 2006; 74:036617. [PMID: 17025774 DOI: 10.1103/physreve.74.036617] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2005] [Indexed: 05/12/2023]
Abstract
Photonic-crystal fibers are employed to demonstrate widely tunable frequency down-conversion of unamplified 6-fs Ti:sapphire laser pulses through the soliton self-frequency shift induced by the Raman effect. Wavelength shifts as large as 500 nm are achieved for input few-cycle pulses with broadband spectra centered at approximately 820 nm. The central wavelength of the redshifted output of a photonic-crystal fiber is smoothly tuned from the low-frequency edge in the spectrum of the 6-fs Ti:sapphire laser pulse up to 1.35 microm by varying the input energy in the fundamental mode of the fiber.
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Affiliation(s)
- N Ishii
- Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Strasse 1, D-85748 Garching, Germany
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Serebryannikov EE, Zheltikov AM, Ishii N, Teisset CY, Köhler S, Fuji T, Metzger T, Krausz F, Baltuska A. Nonlinear-optical spectral transformation of few-cycle laser pulses in photonic-crystal fibers. Phys Rev E Stat Nonlin Soft Matter Phys 2005; 72:056603. [PMID: 16383767 DOI: 10.1103/physreve.72.056603] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2005] [Indexed: 05/05/2023]
Abstract
Photonic-crystal fibers with special dispersion profiles are shown to provide a high efficiency of spectral transformation of chirped sub-6-fs Ti:sapphire laser pulses. With the wavelength of zero group-velocity dispersion of the fiber lying within the broad spectrum of the input few-cycle pulse, the output spectra feature well-resolved spectral peaks, indicative of soliton self-frequency shift, four-wave mixing, and Cherenkov emission of dispersive waves. We demonstrate that up to 3% of radiation energy at the output of the fiber can be confined within a spectrally isolated soliton peak centered at , which is ideally suited as a seed for Nd:YAG- and ytterbium-based laser devices.
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Affiliation(s)
- E E Serebryannikov
- Physics Department, International Laser Center, M. V. Lomonosov Moscow State University, Vorob'evy gory, Moscow 119992, Russia
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Teisset C, Ishii N, Fuji T, Metzger T, Köhler S, Holzwarth R, Baltuska A, Zheltikov A, Krausz F. Soliton-based pump-seed synchronization for few-cycle OPCPA. Opt Express 2005; 13:6550-6557. [PMID: 19498670 DOI: 10.1364/opex.13.006550] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We demonstrate a significant simplification of the scheme for few-cycle Optical Parametric Chirped Pulse Amplification (OPCPA) which results in the elimination of a picosecond's master oscillator and electronic synchronization loops. A fraction of a broadband seed pulse centered at 760 nm from a 70-MHz Ti:sapphire oscillator was frequency-shifted in a photonic crystal fiber to enable synchronized seeding of a picosecond's Nd:YAG pump laser. The seed radiation at 1064 nm is produced in the soliton regime which makes it inherently more intense and stable in comparison with other methods of frequency conversion. The remaining fraction of the Ti:sapphire output is amplified with a FWHM bandwidth of 250 nm in a single timing-jitter-free OPCPA stage. Our work opens up the exciting possibility to use sub-picosecond's pump pulses from highly efficient Yb-based amplifiers for jitter-less parametric amplification of carrier-envelope phase stabilized pulses from Ti:sapphire oscillators.
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Mihailova B, Mintova S, Karaghiosoff K, Metzger T, Bein T. Nondestructive Identification of Colloidal Molecular Sieves Stabilized in Water. J Phys Chem B 2005; 109:17060-5. [PMID: 16853175 DOI: 10.1021/jp051413v] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The encapsulation of small quaternary ammonium ions in zeolite frameworks could be used as a base for investigation of the crystallization process of colloidal (nanosized) molecular sieves stabilized in water with Raman and (13)C NMR spectroscopic methods. The organic-framework interactions in colloidal microporous materials with LTA, FAU, BEA, and MFI topology have been considered; the results show that the crystallinity of nanosized particles with monomodal particle size distribution stabilized in water can be examined using the vibrational and magnetic resonance spectral features of the organic template molecules occluded in the specific pores and cages in the zeolite framework. The molecular packing effect and restricted mobility due to specific organic/framework interactions result in shifts and substantial broadening of the (13)C NMR signals, as well as in changes of the positions and the relative intensities of the Raman peaks. The spectroscopic methods are very efficient for analyzing the crystalline structures of nanosized molecular sieves stabilized in aqueous suspensions due to no restrictions related to the particle size.
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Affiliation(s)
- B Mihailova
- Department of Chemistry, University of Munich, Butenandtstrasse 11(E), D-81377 Munich, Germany
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Metzger T, Irawan A, Tsotsas E. Einfluss von Porenstruktur und Produkttiefe auf das Trocknungsverhalten mittels eines Netzwerkmodells. CHEM-ING-TECH 2005. [DOI: 10.1002/cite.200590256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Petkov N, Mintova S, Jean B, Metzger T, Bein T. Functionalized cubic mesostructured silica films. Materials Science and Engineering: C 2003. [DOI: 10.1016/j.msec.2003.09.134] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Wanner C, Krane V, Metzger T, Quaschning T. Lipid changes and statins in chronic renal insufficiency and dialysis. J Nephrol 2001; 14 Suppl 4:S76-80. [PMID: 11798151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
Chronic renal failure patients suffer from a secondary form of complex dyslipidemia, similar to the so-called atherogenic dyslipidemia in insulin resistant patients or to diabetic dyslipidemia. The most important abnormalities are an increase in the serum level of triglyceride (elevated VLDL-remnants/IDL), small LDL particles and a low HDL cholesterol. The highly atherogenic LDL subclass, namely LDL-6 or small dense LDL, accumulates in hypertriglyceridemic diabetic hemodialysis patients. All these lipoprotein particles contain apoB, thus much of this complex disorder can be summarized as an elevation of triglyceride-rich apoB containing complex lipoprotein particles. Growing evidence suggests that all of the components of this type of dyslipidemia are independently atherogenic. Further disturbances exist in the dynamics of cholesterol exchange between the various lipoprotein particles and in transport from cells to catabolic sites. The European Joint Task Force and the US National Cholesterol Education Program expert panel have issued guidelines for the general population to lower the cardiovascular risk in hyper- and dyslipidemias. There is preliminary consensus that these guidelines should be applied to dialysis patients. However, the genesis of atherosclerosis in the dialysis population may be different and real benefit from lipid-lowering has not yet been demonstrated in this population. Large-scale, prospective randomized trials (4D-trial, HARP) are underway to determine whether statins reduce cardiovascular complications in diabetic and non-diabetic patients with end-stage renal disease (ESRD) and on hemodialysis treatment.
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Affiliation(s)
- C Wanner
- Department of Medicine, Division of Nephrology, University of Würzburg, Germany.
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Abstract
Patients with end-stage renal disease (ESRD) suffer from a secondary form of complex dyslipidemia consisting of both quantitative and qualitative abnormalities in serum lipoproteins resulting from alterations in lipoprotein metabolism and composition. The prominant features of uremic dyslipidemia are an increase in serum triglyceride levels (due to elevated very low density lipoprotein [VLDL]-remnants and intermediate-density lipoprotein [IDL]) and low high-density lipoprotein (HDL) cholesterol. Low-density lipoprotein (LDL) cholesterol often is normal, but the cholesterol may originate from the atherogenic small and dense LDL subclass (sdLDL). The apolipoprotein B (apoB)-containing part of the lipoprotein may undergo modifications (enzymatic- and advanced glycation end-product [AGE]-peptide modification, oxidation, or glycosilation). Modifications contribute to impaired LDL receptor-mediated clearance from plasma and promote prolonged circulation. While LDL particles undergo a vicious cycle of accumulation and modification, reverse cholesterol transport is also impaired due to low lecithin:cholesterol acyltransferase (LCAT) and paraoxonase activity. Therefore, discoid HDL particles are structurally altered and hepatic cholesterol clearance is limited. The composition of HDL may also be altered during states of inflammation. The contribution of this complex and atherogenic form of dyslipidemia to cardiovascular disease in patients with renal disease is unclear at present. Most studies are negative in demonstrating the predictive power of serum lipids for the development of cardiovascular disease. This is most likely due to interference with deteriorating aspects of the activated acute-phase response. Nevertheless, patients with renal disease belong to a very high cardiovascular risk group and dyslipidemia should most likely be subjected to sufficient lipid-lowering therapy in most patients. Because it is also still unclear whether we have available therapies with sufficient impact on LDL size, remnant lipoprotein-lowering, and restoration of HDL function, we urgently need the results from large scale intervention trials such as the 4D-trial and the CHORUS study.
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Affiliation(s)
- T Quaschning
- Department of Medicine, Division of Nephrology, University of Würzburg, Würzburg, Germany
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Wanner C, Metzger T, Krane V. Lipid lowering in end-stage renal disease. Saudi J Kidney Dis Transpl 2001; 12:3-8. [PMID: 18209353] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/25/2023] Open
Affiliation(s)
- C Wanner
- Department of Medicine, Division of Nephrology, University of Würzburg, Würzburg, Germany
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Abstract
BACKGROUND Atherosclerosis, a major problem in patients on chronic hemodialysis, has been characterized as an inflammatory disease. C-reactive protein (CRP), the prototypical acute phase protein in humans, is a predictor of cardiovascular mortality in the general population. We hypothesize that several of the classic, as well as nontraditional, cardiovascular risk factors may respond to acute phase reactions. An activated acute phase response may influence or predict cardiovascular risk. METHODS In 280 stable hemodialysis patients, serum lipids, apolipoproteins (apo) A-I and B, lipoprotein(a) [Lp(a)], fibrinogen, and serum albumin (Salb) were determined in relation to CRP and serum amyloid A (SAA), two sensitive markers of an acute phase response. Mortality was monitored prospectively over a two year period. RESULTS Serum CRP and SAA were found to be elevated (more than 8 and more than 10 mg/liter, respectively) in 46% and 47% of the patients in the absence of clinically apparent infection. Patients with elevated CRP or SAA had significantly higher serum levels of Lp(a), higher plasma fibrinogen, and lower serum levels of high-density lipoprotein cholesterol, apo A-I, and Salb than patients with normal CRP or SAA. The rise in Lp(a) concentration was restricted to patients exhibiting high molecular weight apo(a) isoforms. During follow-up, 72 patients (25.7%) had died, mostly due to cardiovascular events (58%). Overall mortality and cardiovascular mortality were significantly higher in patients with elevated CRP (31% vs. 16%, P < 0.0001, and 23% vs. 5%, P < 0.0001, respectively) or SAA (29% vs. 19%, P = 0.004, and 20 vs. 10%, P = 0.008, respectively) and were also higher in patients with Salb of lower than 40 g/liter (44% vs. 14%, P < 0.0001, and 34% vs. 6%, P < 0.0001, respectively). Univariate Cox regression analysis demonstrated that age, diabetes, pre-existing cardiovascular disease, body mass index, CRP, SAA, Salb, fibrinogen, apo A-I, and Lp(a) were significantly associated with the risk of all-cause and cardiovascular mortality. During multivariate regression analysis, SAA, fibrinogen, apo A-I, and Lp(a) lost their predictive values, but age and CRP remained powerful independent predictors of both overall death and cardiovascular death. CONCLUSION These results suggest that a considerable number of hemodialysis patients exhibit an activated acute phase response, which is closely related to high levels of atherogenic vascular risk factors and cardiovascular death. The mechanisms of activated acute phase reaction in patients on chronic hemodialysis remain to be identified. A successful treatment of the inflammatory condition may improve long-term survival in these patients.
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Affiliation(s)
- J Zimmermann
- Department of Medicine, University Clinic Würzburg, Germany.
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Uhl G, Lin Z, Metzger T, Dar DE. Dopamine transporter mutants, small molecules, and approaches to cocaine antagonist/dopamine transporter disinhibitor development. Methods Enzymol 1998; 296:456-65. [PMID: 9779467 DOI: 10.1016/s0076-6879(98)96033-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- G Uhl
- Molecular Neurobiology Branch, NIDA-IRP, Baltimore, Maryland, USA
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Metzger T, Höpler R, Born E, Ambacher O, Stutzmann M, Stömmer R, Schuster M, Göbel H, Christiansen S, Albrecht M, Strunk HP. Defect structure of epitaxial GaN films determined by transmission electron microscopy and triple-axis X-ray diffractometry. ACTA ACUST UNITED AC 1998. [DOI: 10.1080/01418619808221225] [Citation(s) in RCA: 345] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Jeffrey IW, Kadereit S, Meurs EF, Metzger T, Bachmann M, Schwemmle M, Hovanessian AG, Clemens MJ. Nuclear localization of the interferon-inducible protein kinase PKR in human cells and transfected mouse cells. Exp Cell Res 1995; 218:17-27. [PMID: 7737357 DOI: 10.1006/excr.1995.1126] [Citation(s) in RCA: 101] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The levels and subcellular distribution of the interferon-inducible double-stranded RNA-dependent protein kinase PKR have been measured in human Daudi cells and stably transfected mouse NIH 3T3 cells expressing the human protein kinase. Immunofluorescence of intact cells and quantitative immunoblotting of cell extracts indicate that PKR occurs in both the cytoplasm and the cell nucleus, with staining specifically in the nucleolus. The ratio of cytoplasmic to nuclear PKR is approximately 5:1 in control cells; in response to interferon treatment the protein kinase is induced severalfold in the cytoplasm whereas the level in the nucleus does not increase significantly. Analysis of individual transfected cells by confocal microscopy reveals a pattern of distribution of PKR similar to that in Daudi cells, with immunostaining of cytoplasm and nucleoli. Similar results are observed whether cells expressing wild-type PKR or a catalytically inactive mutant form of the kinase are analyzed, but untransfected 3T3 cells are not stained by the antibody used. Two-dimensional isoelectric focusing analysis of PKR in whole cell extracts reveals the presence of multiple forms with different pI values whereas similar analysis of the nuclear fraction indicates only one predominant species with a relatively basic pI. These results suggest that PKR may have a role in the cell nucleus as well as the cytoplasm and that the subcellular distribution of the protein kinase may be related to post-translational modifications.
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Affiliation(s)
- I W Jeffrey
- Division of Biochemistry, St. George's Hospital Medical School, London, United Kingdom
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Metzger T, Rougier P. Modification of strategies induced by climbers' level of expertise during postures characterized by high lateral inter limb distances. J Biomech 1994. [DOI: 10.1016/0021-9290(94)91008-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Taraszka KS, Chen E, Metzger T, Chance MR. Identification of structural markers for vitamin B12 and other corrinoid derivatives in solution using FTIR spectroscopy. Biochemistry 1991; 30:1222-7. [PMID: 1991101 DOI: 10.1021/bi00219a009] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The identification of structural markers for B12/protein interactions is crucial to a complete understanding of vitamin B12 transport and metabolic reaction mechanisms of B12 coenzymes. Fourier transform infrared spectroscopy can provide direct measurements of changes in the side chains and corrin ring resulting from B12/protein interactions. Using FTIR spectroscopy in various solvent systems, we have identified structural markers for corrinoids in the physiological state. We assign the major band (denoted B), which occurs at ca. 1630 cm-1 in D2O and ca. 1675 cm-1 in ethanol, to the amide I C=O stretching mode of the propionamide side chains of the corrin ring. The lower frequency of band B in D2O versus ethanol is due to the greater hydrogen-bonding properties of D2O that stabilize the charged amide resonance form. Since the propionamides are known to be important in protein binding, band B is a suitable marker for monitoring the interaction of these side chains with proteins. We assign bands at ca. 1575 and 1545 cm-1 (denoted C and D) as breathing modes of the corrin ring on the basis of the bands' solvent independence and their sensitivity to changes in axial ligation. As the sigma-donating strength of the axial ligands increases, the frequencies of bands C and D decrease, possibly indicating a lengthening of the corrin conjugated system. Band A, the known cyanide stretching frequency at ca. 2130 cm-1, probes the cobalt-carbon distance in cyanocorrinoids. As the frequency of band A increases, the cobalt-carbon bond strength should decrease.
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Affiliation(s)
- K S Taraszka
- Department of Chemistry, Georgetown University, Washington, D.C. 20057
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Affiliation(s)
- C R Goldfarb
- Department of Radiology, Beth Israel Medical Center, New York, NY 10003
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