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240 results on '"Weidner, D."'

3. Reduced Level of Philadelphia Chromosome Positive (Ph+) Cells in Lineage Negative Side Population Bone Marrow Progenitor Cells from Patients with Chronic Myeloid Leukemia (CML)

Author

Weidner, D. A., Wang, Rui-Yu Y., Zhao, Shourong, Calvert, L., Kuehnle, I., Kantarjian, H., Brenner, M. K., Goodell, M. A., Andreeff, M., Hiddemann, Wolfgang, editor, Haferlach, Torsten, editor, Unterhalt, Michael, editor, Büchner, Thomas, editor, and Ritter, Jörg, editor

Published
2003
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4. Neutrophil Extracellular Traps (NETs) and their role in the Development and Growth of Human Salivary Stones

Author

Schapher, M, additional, Koch, M, additional, Weidner, D, additional, Scholz, M, additional, Wirtz, S, additional, Mahajan, A, additional, Herrmann, I, additional, Singh, J, additional, Knopf, J, additional, Leppkes, M, additional, Schauer, C, additional, Grüneboom, A, additional, Alexiou, C, additional, Schett, G, additional, Iro, H, additional, Munoz, L, additional, and Herrmann, M, additional

Published
2021
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8. Aggregated neutrophil extracellular traps resolve inflammation by proteolysis of cytokines and chemokines and protection from antiproteases

Author

Hahn, J., Schauer, C., Czegley, C., Kling, L., Petru, L., Schmid, B., Weidner, D., Reinwald, C., Biermann, MHC., Blunder, S., Ernst, J., Lesner, A., Bäuerle, T., Palmisano, R., Christiansen, S., Herrmann, M., Bozec, A., Gruber, R., Schett, G., Hoffmann, MH., and Publica

Abstract

Papillon-Lefèvre syndrome (PLS) is characterized by nonfunctional neutrophil serine proteases (NSPs) and fulminant periodontal inflammation of unknown cause. Here we investigated neutrophil extracellular trap (NET)-associated aggregation and cytokine/chemokine-release/degradation by normal and NSP-deficient human and mouse granulocytes. Stimulated with solid or soluble NET inducers, normal neutrophils formed aggregates and both released and degraded cytokines/chemokines. With increasing cell density, proteolytic degradation outweighed release. Maximum output of cytokines/chemokines occurred mostly at densities between 2 × 107 and 4 × 107 neutrophils/cm3. Assessment of neutrophil density in vivo showed that these concentrations are surpassed during inflammation. Association with aggregated NETs conferred protection of neutrophil elastase against a1-antitrypsin. In contrast, eosinophils did not influence cytokine/chemokine concentrations. The proteolytic degradation of inflammatory mediators seen in NETs was abrogated in Papillon-Lefèvre syndrome (PLS) neutrophils. In summary, neutrophil-driven proteolysis of inflammatory mediators works as a built-in safeguard for inflammation. The absence of this negative feedback mechanism might be responsible for the nonresolving periodontitis seen in PLS.-Hahn, J., Schauer, C., Czegley, C., Kling, L., Petru, L., Schmid, B., Weidner, D., Reinwald, C., Biermann, M. H. C., Blunder, S., Ernst, J., Lesner, A., Bäuerle, T., Palmisano, R., Christiansen, S., Herrmann, M., Bozec, A., Gruber, R., Schett, G., Hoffmann, M. H. Aggregated neutrophil extracellular traps resolve inflammation by proteolysis of cytokines and chemokines and protection from antiproteases.

Published
2019

14. Phase transformations in hypereutectic MgO-Y2O3 nanocomposites at 5.5 GPa.

Author

Şavklıyıldız, İ., Akdoğan, E. K., Zhong, Z., Wang, L., Weidner, D., Vaughan, M., Croft, M. C., and Tsakalakos, T.

Subjects
NANOCOMPOSITE materials, HIGH temperatures, SYNCHROTRONS, MAGNESIUM oxide, YTTRIUM
Abstract

Hypereutectic 0.8MgO-0.2Y2O3 nanocomposites were studied using high pressure and high temperature in situ synchrotron energy dispersive x-ray diffractometry at 5.5 GPa and 1273 K. Polymorphic transformations in the Y2O3 phase, which resulted in a quadruple phase equilibria among cubic, hexagonal, and monoclinic phases with cubic MgO, were observed at 298 K under 5.5 GPa-a pressure much smaller than the pressures at which polymorphic transitions in macroscopic Y2O3. Time-resolved diffractometry at (1273 K, 5.5 GPa, 120 min) revealed a 0.87% expansive volumetric lattice strain in MgO, and is attributed to solid solution formation with Y2O3 which is otherwise absent at ambient conditions. The residual MgO unit cell volume expansion is 0.69% at 298 K, which is indicative that yttrium remained in solid solution. The macroscopic shrinkage due to densification at (1273 K, 5.5 GPa, 120 min) is 3.45% by volume. The partial molar volume of Y3+ in the solid solution is smaller than its molar volume in the pure state per thermodynamic considerations. The importance of repulsion among O2- ions in the immediate vicinity of a Mg2+ vacancy as well as misfit strain due to differences in ionic radii upon Y3+ substitution on Mg2+ sites is presented. A self-consistent model and explanation for the observed concomitant occurrence of cubic → monoclinic and cubic → hexagonal polymorphic transitions in Y2O3 and their stabilization at room temperature is proposed. [ABSTRACT FROM AUTHOR]

Published
2013
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18. Pressure effects on phase equilibria and solid solubility in MgO-Y2O3 nanocomposites.

Author

Akdoğan, E. K., Şavklιyιldιz, İ., Berke, B., Zhong, Z., Wang, L., Weidner, D., Croft, M. C., and Tsakalakos, T.

Subjects
DIAMOND anvil cell, NANOCOMPOSITE materials, X-ray diffraction, HYDROSTATIC pressure, CRYSTALLIZATION, SOLID solutions
Abstract

We study the temperature and pressure dependence of phase evolution in the 0.5MgO-0.5Y2O3 nanocomposite system using a diamond anvil apparatus in conjunction with in situ synchrotron energy dispersive x-ray diffraction at 7 GPa hydrostatic pressure. At (298 K, 7.0 GPa), structural transformations in the Y2O3 phase are observed, giving rise to the co-existence of its cubic, hexagonal, and monoclinic polymorphs together with cubic MgO. An increase in temperature to 1273 K causes the crystallinity of the Y2O3 hexagonal and monoclinic phases to increase. Isothermal and isobaric hold at (1273 K, 7.0 GPa) for 60 min results in yttrium dissolution in cubic MgO, causing ∼1.0% expansive volumetric lattice strain despite the large differences in the ionic radii of the cations. Cooling the nanocomposite to (298 K, 0 GPa) after a 60 min soak yields four phase co-existence among cubic MgO and cubic, hexagonal, and monoclinic Y2O3. The residual MgO unit cell volume expansion is 0.69% at 298 K, indicating solid solution formation at room temperature despite large differences in the ionic radii of Mg2+ and Y3+. The macroscopic shrinkage due to densification is 3% by volume. Thermodynamic considerations suggest that the relative molar partial volume of Y3+ in MgO is a negative quantity, indicating that the partial molar volume of Y3+ in the solid solution is smaller than its molar volume in the pure state. Aging of the nanocomposites for 240 h does not change the observed 4 phase co-existence. We propose a crystallographic model in which the observed volumetric expansion of the MgO unit cell is primarily attributed to two hydrostatic expansive strain components accompanying solid solution formation: (i) Coulomb repulsion among O2- ions in the immediate vicinity of Mg2+ vacancies, and (ii) misfit strain due to differences in ionic radii upon Y3+ substitution on Mg2+ sites. [ABSTRACT FROM AUTHOR]

Published
2012
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19. Misuse Of Temazepam

Author

Launchbury, A. P., Drake, J., Seager, H., Fox, R., Beeching, N. J., Morrison, C., Ruben, S., Garvey, T., Moonman, D., Seidl, A., Seidl, F. W., Crowe, R., and Weidner, D.

Published
1992

24. Pressure-induced phase transition and pressure dependence of crystal structure in low (α) and Ca/Al-doped cristobalite.

Author

Parise, J. B., Yeganeh-Haeri, A., Weidner, D. J., Jorgensen, J. D., and Saltzberg, M. A.

Subjects
SILICON oxide, CRISTOBALITE, SEMICONDUCTOR doping
Abstract

Presents a study that investigated the phase stability and atomic-level compression mechanisms for both silicon oxide cristobalite and for cristobalite partially stabilized by calcium/aluminum doping. Details of the experiment; Results and discussion; Conclusion.

Published
1994
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25. Blood-borne phagocytes internalize urate microaggregates and prevent intravascular NETosis by urate crystals

Author

Pieterse, E., Jeremic, I., Czegley, C., Weidner, D., Biermann, M.H., Veissi, S., Maueroder, C., Schauer, C., Bilyy, R., Dumych, T., Hoffmann, M., Munoz, L.E., Bengtsson, A.A., Schett, G., Vlag, J. van der, Herrmann, M., Pieterse, E., Jeremic, I., Czegley, C., Weidner, D., Biermann, M.H., Veissi, S., Maueroder, C., Schauer, C., Bilyy, R., Dumych, T., Hoffmann, M., Munoz, L.E., Bengtsson, A.A., Schett, G., Vlag, J. van der, and Herrmann, M.

Abstract

Contains fulltext : 172035.pdf (publisher's version ) (Open Access), Hyperuricemia is strongly linked to cardiovascular complications including atherosclerosis and thrombosis. In individuals with hyperuricemia, needle-shaped monosodium urate crystals (nsMSU) frequently form within joints or urine, giving rise to gouty arthritis or renal calculi, respectively. These nsMSU are potent instigators of neutrophil extracellular trap (NET) formation. Little is known on the mechanism(s) that prevent nsMSU formation within hyperuricemic blood, which would potentially cause detrimental consequences for the host. Here, we report that complement proteins and fetuins facilitate the continuous clearance by blood-borne phagocytes and resident macrophages of small urate microaggregates (UMA; <1 mum in size) that initially form in hyperuricemic blood. If this clearance fails, UMA exhibit bipolar growth to form typical full-sized nsMSU with a size up to 100 mum. In contrast to UMA, nsMSU stimulated neutrophils to release NETs. Under conditions of flow, nsMSU and NETs formed densely packed DNase I-resistant tophus-like structures with a high obstructive potential, highlighting the importance of an adequate and rapid removal of UMA from the circulation. Under pathological conditions, intravascularly formed nsMSU may hold the key to the incompletely understood association between NET-driven cardiovascular disease and hyperuricemia.

Published
2016

26. Art. Kirchenraum

Author

Weidner, Daniel, Weidner, D ( Daniel ), Mauz, Andreas, Weidner, Daniel, Weidner, D ( Daniel ), and Mauz, Andreas

Published
2016

27. Animal Models of Rheumatoid Arthritis (I) : Pristane-Induced Arthritis in the Rat

Author

Tuncel, J., Haag, S., Hoffmann, M. H., Yau, A. C., Hultqvist, M., Olofsson, P., Bäcklund, J., Nandakumar, Kutty Selva, Weidner, D., Fischer, A., Leichsenring, A., Lange, F., Haase, C., Lu, S., Gulko, P. S., Steiner, G., Holmdahl, R., Tuncel, J., Haag, S., Hoffmann, M. H., Yau, A. C., Hultqvist, M., Olofsson, P., Bäcklund, J., Nandakumar, Kutty Selva, Weidner, D., Fischer, A., Leichsenring, A., Lange, F., Haase, C., Lu, S., Gulko, P. S., Steiner, G., and Holmdahl, R.

Abstract

BACKGROUND: To facilitate the development of therapies for rheumatoid arthritis (RA), the Innovative Medicines Initiative BTCure has combined the experience from several laboratories worldwide to establish a series of protocols for different animal models of arthritis that reflect the pathogenesis of RA. Here, we describe chronic pristane-induced arthritis (PIA) model in DA rats, and provide detailed instructions to set up and evaluate the model and for reporting data. METHODS: We optimized dose of pristane and immunization procedures and determined the effect of age, gender, and housing conditions. We further assessed cage-effects, reproducibility, and frequency of chronic arthritis, disease markers, and efficacy of standard and novel therapies. RESULTS: Out of 271 rats, 99.6% developed arthritis after pristane-administration. Mean values for day of onset, day of maximum arthritis severity and maximum clinical scores were 11.8+/-2.0 days, 20.3+/-5.1 days and 34.2+/-11 points on a 60-point scale, respectively. The mean frequency of chronic arthritis was 86% but approached 100% in long-term experiments over 110 days. Pristane was arthritogenic even at 5 microliters dose but needed to be administrated intradermally to induce robust disease with minimal variation. The development of arthritis was age-dependent but independent of gender and whether the rats were housed in conventional or barrier facilities. PIA correlated well with weight loss and acute phase reactants, and was ameliorated by etanercept, dexamethasone, cyclosporine A and fingolimod treatment. CONCLUSIONS: PIA has high incidence and excellent reproducibility. The chronic relapsing-remitting disease and limited systemic manifestations make it more suitable than adjuvant arthritis for long-term studies of joint-inflammation and screening and validation of new therapeutics.

Published
2016
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41. Elastic properties of alpha quartz and the alkali halides based on an interatomic force model.

Author

Weidner, D. J and Simmons, G

Subjects
Geophysics
Abstract

A two-body central-force atomic model can be used to describe accurately the elastic properties of alpha quartz if the nontetrahedral O:O forces are included. The strength of the Si:O interaction has little effect on the bulk modulus. The technique is sufficiently general to allow calculations of the elastic properties of a specified structure under arbitrary pressure from a complete description of the interatomic forces. The elastic constants for the NaCl structure and the CsCl structure are examined. Our model includes two-body, central, anion-anion, anion-cation, and electrostatic interactions.

Published
1972

46. An improved static diffusion model of the thermosphere

Author

Chambers, J. L and Weidner, D. K

Subjects
Meteorology
Abstract

Static diffusion model of thermosphere with allowance for temperature and chemical composition and not limited by constant 120 km boundary conditions

Published
1970

49. Models of Earth's Atmosphere (120 to 1000 Km)

Author

Weidner, D. K, Hasseltine, C. L, Smith, R. E, and Mills, S. A

Subjects
Astrodynamics
Abstract

Atmospheric conditions encountered by a spacecraft in orbit about the Earth are important factors in space vehicle design, mission planning, and mission operations. Density is the primary atmospheric property that affects the spacecraft's orbital altitude, lifetime, and motion in the altitude range of 120 to 1000 kilometers. Near the lower limit of this range where density is greatest, a spacecraft will generally remain in orbit for a very short time; near the upper limit, the density effect on orbital lifetime is almost negligible. Density directly affects the torques which result from aerodynamic interaction between the space vehicle and the atmosphere; such torques must be considered in design of spacecraft attitude control systems. Density scale height is required in heating calculations for space vehicles re-entering the Earth's upper atmosphere. Density as well as chemical composition and temperature are needed in calculating a spacecraft's drag coefficient. Chemical composition and temperature also are required in the design of experiment sensors to be flown in this altitude range. Because of variability of atmospheric conditions with spatial location and solar condition, invariant models of the Earth's atmosphere (120 to 1000 kilometers) would not be useful for most engineering applications. Therefore, this monograph presents a computerized version of Jacchia's prediction method to provide models of the Earth's atmosphere which vary with solar condition and location. The resulting atmospheric models, which are predicted for particular times and locations, provide atmospheric density, chemical composition, temperature, molecular mass, and density scale height between 120 and 1000 kilometers altitude. In addition to the computerized method, a quick-look prediction method is given that may be used to obtain an estimate of atmospheric density for any time and spatial location without the use of a computer. A sample problem illustrates this method. Both methods provide models of mean density and models having reasonable upper extremes for density. The analytical approaches in both methods are considered to be the best available, but they could be refined considerably by additional data and study. Information contained in this monograph applies to altitudes between 120 and 1000 kilometers; other design criteria monographs in this series will provide atmospheric information below this altitude region.

Published
1969

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