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  • 1
    Electronic Resource
    Electronic Resource
    Oxidative photochemical decarboxylation of zaragozic acid A (1995)
    Springer
    Cellular and molecular life sciences 51 (1995), S. 252-255 
    Details
    ISSN: 1420-9071
    Keywords: Squalene synthase inhibitors ; zaragozic acids ; squalestatins ; oxidative photochemical decarboxylation ; structure-activity relationship
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract A unique decomposition reaction of the novel squalene synthase inhibitors called zaragozic acids has been studied. Under very mild conditions, e.g. by merely exposing their solutions to air and visible light at ambient temperature, these compounds, characterized by the 2,8-dioxabicyclo[3.2.1]octane-4,6,7-trihydroxy-3,4,5-tricarboxylic acid core, rapidly decompose. As relatively stable intermediates in the cascade of decomposition, the biologically active 2,8-dioxabicyclo[3.2.1]octane-6,7-dihydroxy-4-keto-5-caroxylic acid (or 3,4-decarboxy-4-dehydro) derivatives of these compounds have been isolated in ca. 20% yield. Derivatization on the highly reactive 4-carbonyl group yields stable derivatives, several of which are potent inhibitors of squalene synthase. Further decomposition results in the elimination of C3 and C4 atoms and the carboxylic acid on C5, the oxidation of C5 to carboxylic acid and the liberation of the oxo group on C1. Specific results obtained with zaragozic acid A, a key representative of the family of these potent cholesterol-lowering agents, are presented in this study.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01931107
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  • 2
    Electronic Resource
    Electronic Resource
    Infusion of pH 2.0 D-chiro-inositol glycan insulin putative mediator normalizes plasma glucose in streptozotocin diabetic rats at a dose equivalent to insulin without inducing hypoglycaemia (1996)
    Springer
    Diabetologia 39 (1996), S. 731-734 
    Details
    ISSN: 1432-0428
    Keywords: Keywords Insulin ; mediator ; d-chiro-inositol ; euglycaemia ; manganese.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We compared the effects of infusing a chemically defined chiro-inositol glycan putative insulin mediator with an equivalent dose of insulin in low-dose (45 mg/kg) streptozotocin diabetic rats. Insulin decreased plasma glucose levels from 17.32 ± 0.17 to 3.96 ± 0.064 mmol/l (p 〈 0.0002) in 120 min, a decrease of 77.13 %, while the putative mediator promoted a decrease in plasma glucose from 14.85 ± 0.084 to 7.22 ± 0.13 mmol/l (p 〈 0.007) in 60 min. The putative mediator maintained euglycaemia over the ensuing 60 min with a plasma glucose level of 7.01 ± 0.10 mmol/l at 120 min. Thus, insulin further reduced the plasma glucose from euglycaemia at 60 min to produce hypoglycaemia at 120 min. The lack of production of hypoglycaemia by the putative mediator can be explained by its inhibition of glucose-stimulated insulin secretion by the islet beta cells, thus providing a potential negative feedback regulatory mechanism; or by its selective action on muscle to increase glycogen synthesis. The significance of these results in terms of future directions in drug design is herein considered. [Diabetologia (1996) 39: 731–734]
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00418546
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  • 3
    Electronic Resource
    Electronic Resource
    Infusion of pH 2.0 d-chiro-inositol glycan insulin putative mediator normalizes plasma glucose in streptozotocin diabetic rats at a dose equivalent to insulin without inducing hypoglycaemia (1996)
    Springer
    Diabetologia 39 (1996), S. 731-734 
    Details
    ISSN: 1432-0428
    Keywords: Insulin ; mediator ; d-chiro-inositol ; euglycaemia ; manganese
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We compared the effects of infusing a chemically defined chiro-inositol glycan putative insulin mediator with an equivalent dose of insulin in low-dose (45 mg/kg) streptozotocin diabetic rats. Insulin decreased plasma glucose levels from 17.32±0.17 to 3.96±0.064 mmol/l (p〈0.0002) in 120 min, a decrease of 77.13%, while the putative mediator promoted a decrease in plasma glucose from 14.85±0.084 to 7.22±0.13 mmol/l (p〈0.007) in 60 min. The putative mediator maintained euglycaemia over the ensuing 60 min with a plasma glucose level of 7.01±0.10 mmol/l at 120 min. Thus, insulin further reduced the plasma glucose from euglycaemia at 60 min to produce hypoglycaemia at 120 min. The lack of production of hypoglycaemia by the putative mediator can be explained by its inhibition of glucose-stimulated insulin secretion by the islet beta cells, thus providing a potential negative feedback regulatory mechanism; or by its selective action on muscle to increase glycogen synthesis. The significance of these results in terms of future directions in drug design is herein considered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00418546
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  • 4
    Electronic Resource
    Electronic Resource
    A Possible Mechanism of Disordering of Ordered Alloys by Irradiation and Ball Milling (1995)
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 179-181 (Feb. 1995), p. 73-78 
    Details
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/02/01/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.179-181.73.pdf
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  • 5
    Electronic Resource
    Electronic Resource
    Crossed beam reaction of the cyano radical, CN(X 2Σ+), with methylacetylene, CH3CCH (X 1A1): Observation of cyanopropyne, CH3CCCN (X 1A1), and cyanoallene, H2CCCHCN (X 1A′) (1999)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 111 (1999), S. 2857-2860 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The chemical dynamics to form cyanopropyne, CH3CCCN (X 1A1), and cyanoallene, H2CCCHCN (X 1A′), via the neutral–neutral reaction of the cyano radical, CN (X 2Σ+), with methylacetylene, CH3CCH (X 1A1), is investigated under single collision conditions in a crossed molecular beam experiment at a collision energy of 24.7 kJ mol−1. The laboratory angular distribution and time-of-flight spectra of the C4H3N products are recorded at m/e=65, 64, 63, and 62. The reaction of d3-methylacetylene, CD3CCH (X 1A1), with CN radicals yields reactive scattering signal at m/e=68 and m/e=67 demonstrating that two distinct H(D) atom loss channels are open. Forward-convolution fitting of the laboratory data reveal that the reaction dynamics are indirect and governed by an initial attack of the CN radical to the π electron density of the β carbon atom of the methylacetylene molecule to form a long lived CH3CCHCN collision complex. The latter decomposes via two channels, i.e., H atom loss from the CH3 group to yield cyanoallene, and H atom loss from the acetylenic carbon atom to form cyanopropyne. The explicit identification of the CN vs H exchange channel and two distinct product isomers cyanoallene and cyanopropyne strongly suggests the title reaction as a potential route to form these isomers in dark molecular clouds, the outflow of dying carbon stars, hot molecular cores, as well as the atmosphere of hydrocarbon rich planets and satellites such as the Saturnian moon Titan. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.479567
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  • 6
    Electronic Resource
    Electronic Resource
    Crystallization and preliminary crystallographic analysis of the Ras binding domain of RalGDS, a guanine nucleotide dissociation stimulator of the Ral protein (1996)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 52 (1996), S. 1033-1035 
    Details
    ISSN: 1399-0047
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The RalGDS is a guanine nucleotide dissociation stimulator which activates the Ral protein, a Ras-like small GTPase. The C-terminal domain of the RalGDS (C-RalGDS) binds tightly to the effector loop of Ras suggesting that the RalGDS may be a crossing point of two signal tranduction pathways associated with the Ras and Ral proteins. C-RalGDS has been purified and crystallized in space group C2, with unit-cell dimensions a = 108.8, b = 30.7, c = 51.3 Å, β = 91.7° at 277 K and a = 103.8, b = 30.55, c = 51.4 Å, β = 94.9° for data collected at 100 K. The crystals diffract to 1.8 Å at a synchrotron radiation source. To use the multiple-wavelength anomalous diffraction method for phasing, a selenomethionine derivative of the protein has also been crystallized.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0907444996003228
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  • 7
    Electronic Resource
    Electronic Resource
    A new crystal form of bovine heart ubiquinol: cytochrome c oxidoreductase: determination of space group and unit-cell parameters (1995)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 51 (1995), S. 235-239 
    Details
    ISSN: 1399-0047
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Ubiquinol:cytochrome c oxidoreductase, the middle segment of the mitochondrial respiratory chain, is a multi-subunit transmembrane redox enzyme. The purified protein from beef heart mitochondria has been crystallized by three groups in three different forms, but progress toward a structure has been hampered by the limited order (resolution) of the crystals. It has been found that under certain conditions the enzyme crystallizes in a new form suitable for X-ray diffraction studies. These crystals belong to space group C2221 in the orthorhombic system. The cell dimensions are a = 384, b = 118 and c = 177 Å. These new crystals at present diffract to 3.8 Å at best. This is not significantly better than hexagonal [P61(5)22] crystals grown, but the new crystals have the advantage of less spot overlap because of face-centered packing which results in systematic extinctions. More importantly, the availability of the same enzyme in multiple crystal forms may allow phase refinement and extension by the method of molecular replacement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0907444994010486
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  • 8
    Electronic Resource
    Electronic Resource
    Laser-Induced Phase Transitions in Semiconductors (1995)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Materials Research 25 (1995), S. 223-247 
    Details
    ISSN: 0084-6600
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.ms.25.080195.001255
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  • 9
    Electronic Resource
    Electronic Resource
    Crossed beam reaction of the cyanogen radical, CN(X 2Σ+), with acetylene, C2H2(X 1Σg+): Observation of cyanoacetylene, HCCCN(X 1Σ+) (1999)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 110 (1999), S. 7119-7122 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The chemical dynamics to cyanoacetylene, HCCCN(X 1Σ+), formation via the neutral–neutral reaction of cyanogen, CN(X 2Σ+), with acetylene, C2H2(X 1Σg+), is investigated in a crossed molecular beams experiment at a collision energy of 21.1 kJ mol−1. The laboratory angular distribution and time-of-flight spectra of the HCCCN product are recorded at m/e=51 and 50. Forward-convolution fitting of our data reveals that the reaction dynamics are governed by an initial attack of the CN radical to the π electron density of the acetylene molecule to form a HCCHCN collision complex on the 2A′ surface. The four heavy atoms are rotating in plane almost perpendicular to the total angular momentum vector J around the C axis of the complex which undergoes C–H bond rupture through a tight transition state to HCCCN and H. The H atom is emitted almost perpendicular to the HCCCN axis to yield a nearly "sideways" peaking of T(θ). The explicit identification of the cyanoacetylene reaction product represents a solid background for the title reaction to be included with more confidence in reaction networks modeling the chemistry in dark, molecular clouds, outflow of dying carbon stars, hot molecular cores, as well as the atmosphere of hydrocarbon rich planets and satellites such as the Saturnian moon Titan. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.478614
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  • 10
    Electronic Resource
    Electronic Resource
    Crossed beams reaction of atomic carbon, C(3Pj), with d6-benzene, C6D6(X 1A1g): Observation of the per-deutero-1,2-didehydro- cycloheptatrienyl radical, C7D5(X 2B2) (1999)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 110 (1999), S. 6091-6094 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The reaction of atomic carbon, C(3Pj) with per-deutero benzene, C6D6 is investigated at an average collision energy of 32.1 kJ mol−1 using the crossed molecular beams technique combined with a universal mass spectrometric detector. Product angular distributions and time-of-flight spectra of C7D5 and C7D6 are recorded. Forward-convolution fitting of our time-of-flight data (TOFs) and laboratory angular distribution (LAB) together with high level electronic structure calculations on the singlet and triplet C7D6 potential energy surfaces are consistent with the formation of the per-deutero-1,2-didehydrocycloheptatrienyl radical, C7D5. No C7D6 adduct is found experimentally. Our investigations indicate that the carbon atom attacks the benzene molecule face without an entrance barrier to form an initial complex. This undergoes a ring opening to give triplet cycloheptatrienylidene as a C7D6 intermediate. The latter fragments without exit barrier via a C–D bond rupture to yield the per-deutero-1,2-didehydrocycloheptatrienyl isomer, C7D5, and a D atom. This barrierless route for the destruction of benzene may be involved in the synthesis of higher cyclic hydrocarbon derivatives in the interstellar medium, in outflows of dying carbon stars, in hydrocarbon-rich planetary atmospheres, as well as in oxygen-poor combustion flames. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.478514
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