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  • GEOPHYSICS  (6)
  • Polymer and Materials Science  (3)
  • Mutation  (2)
  • 1990-1994  (11)
  • 1
    Digitale Medien
    Digitale Medien
    Reexamination of the polymerization of pyridoxylated hemoglobin with glutaraldehydeThe opinions or assertions contained herein are the private views of the authors, and are not to be construed as official or as reflecting the views of the Department of the Army or the Department of Defense. (1990)
    New York : Wiley-Blackwell
    Biopolymers 29 (1990), S. 871-882 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Pyridoxylated adult human hemoglobin (HbAo) was prepared using a one molar equivalent of pyridoxal 5-phosphate (PLP) per heme and reduced with either NaCNBH3 or NaBH4. A separate sample was pyridoxylated and passed through a mixed-bed ion exchange column without reduction. All three preparations had a P50 of 29 ± 2 torr and a cooperativity of n = 2.4 ± 0.1. These preparations, in both the oxy and deoxy forms, were then treated with 7 equivalents of glutaraldehyde per tetramer at pH 6.8 at 4°C and at room temperature. The polymerization invariably reduced the P50 to 18 ± 2 torr with Hill coefficients of less than 2. These solutions, with or without further reduction using NaCNBH3, all retained the PLP in differing amounts (2-3 moles/tetramer). Methemoglobin concentrations were increased during the polymerization reaction. The normal pyridoxylation procedure, using sodium borohydride reduction, resulted in a number of different molecular species. Polymerization with glutaraldehyde caused a further proliferation of molecular species that could not be separated by anion exchange chromatography or by isoelectric focusing. The extent of polymerization, estimated by gel exclusion chromatography and SDS polyacrylamide gel electrophoresis, was from 40 to 50%. Analysis of the reverse phase chromatograms, which separate the heme and the α- and β-chains, showed extensive polymerization and distribution of the radioactively labeled PLP on the protein for all preparations. All of the polymerized and pyridoxylated samples were unstable, and showed different chromatographic patterns after storage at 4°C for 1 month. Attempts to stabilize these preparations by further reduction with NaCNBH3 gave products with a lower P50 and lower cooperativity. When the reactions were conducted with a purified HbAo, heterogeneity was somewhat decreased compared to the normally used stroma-free hemoglobin, but a large number of molecular species were still formed.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.360290602
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  • 2
    Digitale Medien
    Digitale Medien
    Physical and mechanical properties of highly plasticized pectin/starch films (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 54 (1994), S. 1311-1320 
    Details
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Blends of citrus pectin and high amylose starch plasticized with glycerine were investigated to determine the effect of compositional variables on film properties. Several films with representative compositions were made from sugar beet and almond pectin, and tested for comparison. The films were cast from water onto glass plates, dried, and removed. Mechanical analysis was done using a Rheometrics RSA II solids analyzer. Increasing the glycerine concentration led to decreases in static modulus, dynamic modulus, and tensile strength, but to increases in elongation. Increasing levels of starch in the blend lowered the effect of glycerine on mechanical properties. Oxygen permeability of the films was extremely low. Sugar-beet pectin and almond pectin gave films with mechanical properties comparable to those made with citrus pectin. © 1994 John Wiley & Sons, Inc. This article is a US Government work and, as such, is in the public domain in the United States of America.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/app.1994.070540913
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  • 3
    Digitale Medien
    Digitale Medien
    The effect of anodic surface treatment on the oxidation of catechols at ultrasmall carbon ring electrodes (1991)
    Weinheim : Wiley-Blackwell
    Electroanalysis 3 (1991), S. 899-907 
    Details
    ISSN: 1040-0397
    Schlagwort(e): Microelectrodes ; electrochemical treatment ; carbon ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Electrochemical anodic treatment at ultrasmall carbon ring electrodes appears to result in the formation of an oxide film that displays charge-selective and pH-dependent enhancements following treatment. Voltammetry after treatment in pH 7.4 citrate-phosphate buffer is more Nernstian for dopamine (DA) and less Nernstian for 3,4-dihydroxyphenylacetic acid (DOPAC). However, oxidation in pH 2.8 buffer gives rise to voltammetry that is less Nernstian for both DA and DOPAC. Extensive surface oxidation in potassium hydroxide apparently forms a thick layer that acts like a thin layer reservoir for adsorbed analyte. Voltammetry following extensive treatment is attenuated and peak shaped. Minimal surface oxidation in KOH results in more Nernstian sigmoidal voltammetry with only light current attenuation. The data suggest that an oxide layer formed following anodic treatment is non-uniform and leaves sites of activated carbon exposed on the surface. Furthermore, it appears that this layer has cation-exchange properties giving rise to charge transfer selectivity. A model of the surface formed following anodic oxidation is consistent with previous models involving both surface cleanliness and carbon structure orientation.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/elan.1140030905
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  • 4
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    Effects of cerebral ischemia in mice deficient in neuronal nitric oxide synthase (1994)
    American Association for the Advancement of Science (AAAS)
    Details
    Publikationsdatum: 1994-09-23
    Beschreibung: The proposal that nitric oxide (NO) or its reactant products mediate toxicity in brain remains controversial in part because of the use of nonselective agents that block NO formation in neuronal, glial, and vascular compartments. In mutant mice deficient in neuronal NO synthase (NOS) activity, infarct volumes decreased significantly 24 and 72 hours after middle cerebral artery occlusion, and the neurological deficits were less than those in normal mice. This result could not be accounted for by differences in blood flow or vascular anatomy. However, infarct size in the mutant became larger after endothelial NOS inhibition by nitro-L-arginine administration. Hence, neuronal NO production appears to exacerbate acute ischemic injury, whereas vascular NO protects after middle cerebral artery occlusion. The data emphasize the importance of developing selective inhibitors of the neuronal isoform.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Huang, Z -- Huang, P L -- Panahian, N -- Dalkara, T -- Fishman, M C -- Moskowitz, M A -- NS10828/NS/NINDS NIH HHS/ -- NS2636/NS/NINDS NIH HHS/ -- New York, N.Y. -- Science. 1994 Sep 23;265(5180):1883-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Stroke Research Laboratory, Massachusetts General Hospital, Charlestown 02129.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7522345" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Amino Acid Oxidoreductases/antagonists & inhibitors/deficiency/*metabolism ; Animals ; Arginine/analogs & derivatives/pharmacology ; Brain/enzymology/*metabolism ; Brain Ischemia/complications/*metabolism ; Cerebral Infarction/*etiology ; Cerebrovascular Circulation ; Female ; Male ; Mice ; Mice, Inbred C57BL ; Mice, Knockout ; Mutation ; Neurons/*enzymology ; Nitric Oxide/*metabolism ; Nitric Oxide Synthase ; Nitroarginine
    Print ISSN: 0036-8075
    Digitale ISSN: 1095-9203
    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Publiziert von American Association for the Advancement of Science (AAAS)
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  • 5
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    Endothelial NOS and the blockade of LTP by NOS inhibitors in mice lacking neuronal NOS (1994)
    American Association for the Advancement of Science (AAAS)
    Details
    Publikationsdatum: 1994-07-22
    Beschreibung: Long-term potentiation (LTP) is a persistent increase in synaptic strength implicated in certain forms of learning and memory. In the CA1 region of the hippocampus, LTP is thought to involve the release of one or more retrograde messengers from the postsynaptic cell that act on the presynaptic terminal to enhance transmitter release. One candidate retrograde messenger is the membrane-permeant gas nitric oxide (NO), which in the brain is released after activation of the neuronal-specific NO synthase isoform (nNOS). To assess the importance of NO in hippocampal synaptic plasticity, LTP was examined in mice where the gene encoding nNOS was disrupted by gene targeting. In nNOS- mice, LTP induced by weak intensity tetanic stimulation was normal except for a slight reduction in comparison to that in wild-type mice and was blocked by NOS inhibitors, just as it was in wild-type mice. Immunocytochemical studies indicate that in the nNOS- mice as in wild-type mice, the endothelial form of NOS (eNOS) is expressed in CA1 neurons. These findings suggest that eNOS, rather than nNOS, generates NO within the postsynaptic cell during LTP.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉O'Dell, T J -- Huang, P L -- Dawson, T M -- Dinerman, J L -- Snyder, S H -- Kandel, E R -- Fishman, M C -- DA-00074/DA/NIDA NIH HHS/ -- DA-00266/DA/NIDA NIH HHS/ -- MH-45923/MH/NIMH NIH HHS/ -- etc. -- New York, N.Y. -- Science. 1994 Jul 22;265(5171):542-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Howard Hughes Medical Institute, College of Physicians and Surgeons of Columbia University, New York, NY 10032.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7518615" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Amino Acid Oxidoreductases/antagonists & inhibitors/genetics/*metabolism ; Animals ; Arginine/*analogs & derivatives/pharmacology ; Electric Stimulation ; Endothelium/enzymology ; Hippocampus/drug effects/enzymology/*physiology ; In Vitro Techniques ; *Long-Term Potentiation/drug effects ; Mice ; Mutation ; Nitric Oxide/*metabolism ; Nitric Oxide Synthase ; Nitroarginine ; Pyramidal Cells/drug effects/enzymology/*physiology ; Synaptic Transmission/drug effects
    Print ISSN: 0036-8075
    Digitale ISSN: 1095-9203
    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Publiziert von American Association for the Advancement of Science (AAAS)
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  • 6
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    BATSE observations of bremsstrahlung from electron precipitation events (1992)
    In:  Other Sources
    Details
    Publikationsdatum: 2011-08-24
    Beschreibung: The BATSE on-board burst system has been triggered by over 400 terrestrial electron precipitation events. These are the single largest cause of false triggers. Bremsstrahlung is generated as the precipitating electrons interact in the Earth's atmosphere, or in the spacecraft, and this radiation is detected by the Large Area Detectors, often triggering the instrument into burst mode. Several examples of such events are presented here, and the different classes of events are described. A possible correlation of events to strong magnetospheric activity is presented, and the association of a sub-set of events to a powerful VLF transmitter on the western coast of Australia is described.
    Schlagwort(e): GEOPHYSICS
    Materialart: In: Gamma-ray bursts; Proceedings of the Workshop, Univ. of Alabama, Huntsville, Oct. 16-18, 1991 (A93-40051 16-93); p. 373-377.
    Format: text
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  • 7
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    Observations of reduced ozone concentrations in the tropical stratosphere after the eruption of Mt. Pinatubo (1992)
    In:  Other Sources
    Details
    Publikationsdatum: 2011-08-24
    Beschreibung: Two independent sets of data, one of aerosols from an airborne lidar system, and one of ozone from ozonesonde measurements indicate that significant ozone decreases may have happened as a result of the injection of debris by the Mt. Pinatubo volcano in June 1991. The amount of this reduction maximizes at 24-25 km, near the peak of the aerosol distribution, though a deficit is seen throughout the lower stratosphere between 19 and 28 km. The greatest differences observed prior and subsequent to the eruptions at these altitudes is 18-20 percent.
    Schlagwort(e): GEOPHYSICS
    Materialart: Geophysical Research Letters (ISSN 0094-8276); 19; 11, J
    Format: text
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  • 8
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    Observation of Be-7 on the surface of LDEF spacecraft (1991)
    In:  Other Sources
    Details
    Publikationsdatum: 2011-08-19
    Beschreibung: Significant quantities of Be-7 have been found on the leading edge of the Long Duration Exposure Facility (LDEF), which was returned to earth after almost six years in space. Although the absolute atmospheric concentration of Be-7 needed to explain this detection is extremely small, its concentration at LDEF's altitude must be several orders of magnitude higher than in the stratosphere below, where it is produced by cosmic-ray reactions with atmospheric nitrogen and oxygen nuclei. The detection may lead to the use of Be-7 as an exoatmospheric tracer as well as to studies of surface interactions in space.
    Schlagwort(e): GEOPHYSICS
    Materialart: Nature (ISSN 0028-0836); 349; 678-680
    Format: text
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  • 9
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    Distribution of tropospheric ozone at Brazzaville, Congo, determined from ozonesonde measurements (1992)
    In:  Other Sources
    Details
    Publikationsdatum: 2019-08-28
    Beschreibung: An analysis of 33 ozonesonde launches in Brazzaville, Congo (4 deg S, 15 deg E), between June 1990 and May 1991 is presented. The data indicate highest tropospheric amounts between June and early October, coincident with the dry season and with the presence of enhanced widespread biomass burning. The seasonal cycle of ozone derived from the ozonesonde measurements is in good agreement with the climatological seasonal cycle inferred from the use of satellite data amd both seasonal cycles peak in September. Averaged throughout the year, the integrated amount of ozone derived from the ozonesondes is 44 Dobson units (DU) and is 39 DU using the satellite data. Within the troposphere the highest partial pressures are generally found at pressure levels near 700 mbar (about 3 km). Using simultaneous ozonesonde data from Ascension Island (8 deg S, 15 deg W), examples are presented illustrating that differences in the troposphere are primarily responsible for the observed spatial gradients of total ozone observed by TOMS.
    Schlagwort(e): GEOPHYSICS
    Materialart: Journal of Geophysical Research (ISSN 0148-0227); 97; D12,; 12
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  • 10
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    Distribution of tropospheric ozone determined from satellite data (1990)
    In:  Other Sources
    Details
    Publikationsdatum: 2019-07-12
    Beschreibung: An analysis of more than 22,000 ozone profiles from Stratospheric Aerosol and Gas Experiment I (SAGE I) (1979-1981) and SAGE II (1984-1987) between 50 deg N and 50 deg S is used in conjunction with 9 years (1979-1987) of daily global depictions of total ozone from the TOMS instrument aboard Nimbus 7 to investigate the spatial distribution and seasonal cycle of the integrated amount of ozone in the troposphere. In the tropics, highest concentrations are found in the eastern Atlantic Ocean downwind (west) of Africa and maximize during the time when biomass burning is most prevalent, between July and October. A different seasonal cycle in the tropics is also observed over Indonesia, where a relative maximum is present in the March-April time frame, likewise consistent with when biomass burning is most prevalent. At mid-latitudes, highest concentrations are found downwind of Asia and maximize in the summer. Relatively higher amounts of tropospheric ozone are similarly observed downwind of North America and Europe. At mid-latitudes, the ratio between the amount of tropospheric ozone in the Northern Hemisphere and the amount in the Southern Hemisphere is 1.4, in good agreement with in situ measurements.
    Schlagwort(e): GEOPHYSICS
    Materialart: Journal of Geophysical Research (ISSN 0148-0227); 95; 3599-361
    Format: text
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