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  • 1995-1999  (7)
  • Computational Chemistry and Molecular Modeling  (2)
  • mediator  (2)
  • molecular weight between crosslinks (Mc)  (2)
  • Eucalyptus urophylla  (1)
Source
Material
Years
  • 1995-1999  (7)
Year
Keywords
  • 1
    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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    Paper (German National Licenses)
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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: 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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    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Evaluation of a Statistical Model for the Formation of Poly [Acryloyl Hydroxyethyl Starch] Microspheres (1997)
    Springer
    Pharmaceutical research 14 (1997), S. 475-482 
    Details
    ISSN: 1573-904X
    Keywords: Flory-Rehner model ; dynamic and equilibrium swelling ; molecular weight between crosslinks (Mc) ; degree of derivatization(DD) ; molar ratio (MR)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. To characterize the network structure of Poly (Acryloyl Hydroxyethyl Starch) (Ac-HES) microspheres and test the theoretical model and the hypothesis that the rate of swelling of microspheres is inversely related to the extent of crosslinking. Methods. Microspheres were prepared with varying degrees of derivatization (DD) and molar ratios (MR) and subjected to the characterization of matrix structure by dynamic and equilibrium swelling studies utilizing direct microscopic observation and the Flory-Rehner equation. The dependence of average molecular weight between crosslinking Mc, on DD and MR were compared to test the validity of the model. Results. Study of the dependence of Mc on the microspheres preparation parameters, DD and MR, showed that at constant MR, the Mc decreased with DD, while at constant DD, the Mc initially decreased with MR to a minimum, and then increased with MR, complying with the model prediction. Dynamic swelling of microspheres showed a monotonical increase to equilibrium size featured by two time variables, Tp and Teq, that were dependent on Mc; this permitted a conceptual view of the general structure of the Ac-HES microspheres. The Mc, which was more accurately determined by the weight method (as opposed to volume method), was independent of the size of microspheres although there was evidence of variation among particles within a batch. Conclusions. The results validated the model in describing the polymerization/crosslinking reaction of the Ac-HES microsphere system and suggested that Mc is the principal factor in controlling release.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1012199500072
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Development of a Statistical Model for the Formation of Poly [Acryloyl Hydroxyethyl Starch] Microspheres (1997)
    Springer
    Pharmaceutical research 14 (1997), S. 469-474 
    Details
    ISSN: 1573-904X
    Keywords: poly(Acryloyl Hydroxyethyl Starch) microspheres ; molecular weight between crosslinks (Mc) ; degree of derivatization (DD) ; molar ratio (MR) ; link probability generating function (LPGF)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. To develop a mathematical model for predicting the molecular weight between crosslinks, Mc, of poly[Acryloyl Hydroxyethyl Starch] (Ac-HES) microspheres system and to identify and evaluate the key microsphere preparation parameters which affect the Mc of the formed microsphere structure based on the developed model. Methods. Link probability generating functions (LPGFs) based on the classical branching theory were used to derive a model for the calculation of Mc for the Ac-HES system. Based on the developed model, simulation was made to study the effects of the microsphere preparation variables on Mc of the formed microspheres. The process variables were the degree of derivatization (DD) of the Ac-HES, the molar ratio (MR) of the Ac-HES to acrylamide monomer, the fractional conversion of the unsaturation (α), the initiator efficiency (f), the molar concentration of initiator (I), the fraction of intramolecular cyclization (c), and the total weight of the reactable monomer and polymer (s). Results. A model to describe the crosslinking reaction of Ac-HES system and predict Mc was developed. Simulation based on the model showed that Mc decreased as α increased and reached a limiting value before total conversion. At constant α, Mc initially decreased with MR to a minimum and then increased with MR; while Mc decreased monotonically with DD. I and c affected Mc only at very low α and changes in s and f had no effect on Mc. Conclusions. Simulation based on the model suggested that the most important microsphere preparation parameters influencing Mc of the Ac-HES system are the number of functional groups on the Ac-HES (DD) and the stoichiometry (MR) of the crosslinking reaction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1012111116002
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Functional copper requirement for catechol oxidase activity in plantation Eucalyptus species (1999)
    Springer
    Plant and soil 210 (1999), S. 75-81 
    Details
    ISSN: 1573-5036
    Keywords: copper deficiency ; critical concentration ; Eucalyptus globulus ; Eucalyptus grandis ; Eucalyptus urophylla
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Copper (Cu) deficiency in eucalypts is associated with tree deformation and reduced wood production from plantations. Presently, diagnosis of the early stages of Cu deficiency is unreliable as critical tissue Cu concentrations for tree growth have not been defined. Since wood quality is usually impaired in advance of tree growth, a biochemical test for Cu deficiency was sought for three Eucalyptus species commonly used in plantation forestry (E. globulus Labill., E. grandis Hill ex Maiden and E. urophylla Blake). Foliar Cu requirements for catechol oxidase activity were determined in a glasshouse sand culture study with 10 rates of Cu supply (0, 10-15, 10-14, 10-13, 10-12, 10-11, 10-10, 10-9, 10-7 and 10-5 M). In contrast to shoot dry weight, which only responded to Cu supply in E. urophylla, foliar Cu concentration and catechol oxidase activity, in 140-day-old seedlings, increased with the addition of Cu in all species. Stem lignification also responded to Cu supply in parallel to the activity of catechol oxidase. Functional Cu requirements of 2.4, 2.1 and 2.6 mg kg-1 dry weight for catechol oxidase activity in E. globulus, E. grandis and E. urophylla, respectively, were derived from statistical models fitted to the relationship between catechol oxidase activity and Cu concentrations in recently matured leaves.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004643317708
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Quantum crystallography and the use of kernel projector matrices (1995)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 56 (1995), S. 371-384 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Quantum crystallography is a developing technique for extracting quantum mechanically valid properties from X-ray diffraction experiments. Quantum mechanics and crystallography are joined through the fact that the electron distributions around atoms are the source of X-ray diffraction and electron density distributions are observables that lend themselves readily to quantum mechanical description. Direct contact with the X-ray diffraction data is made by equating the structure factor magnitudes, which are readily obtained from the measured X-ray diffraction intensities, with the magnitudes of certain Fourier transforms of the quantum mechanical description of the electron distribution. The quantum mechanical description of the electron density involves molecular orbitals and an associated matrix. By requiring that the associated matrix be a projector with a normalized trace, while optimizing the fit to the experimental structure factor magnitudes, strong constraints are imposed on the relationship between the X-ray data and the quantum mechanical description of the electron density distribution. The final result should be a wave function that is in good agreement with the X-ray diffraction information and from which a variety of properties, e.g., electron densities and electrostatic potentials, could be extracted. The method for making the fit to the X-ray data involves the use of least-squares calculations in which the defining equations are the structure factor equations and equations that arise from the conditions defining a projector matrix with a normalized trace. The variables are the elements of the projector. It is also possible to refine such parameters as atomic coordinates. The calculations are facilitated by use of good initial projector matrices. For this purpose, a method has been developed for generating projector matrices for large molecules from the sum of kernel matrices. Kernel matrices are obtained from the use of fragments of the known atomic coordinates of the substance of interest and the application of molecular orbital methods in quantum mechanics. The use of fragments is justified by the fact that overlap integrals rapidly approach zero as the distances between atoms increase. © 1995 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560560841
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  • 7
    Electronic Resource
    Electronic Resource
    Kernel projector matrices for leu1—zervamicin (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 60 (1996), S. 1691-1700 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: By performing ab initio calculations on fragments of leu1(SINGLEBOND)zervamicin, it is demonstrated that accurate wave functions can be obtained for this large structure by combining the results from the fragments. Input information consists of atomic coordinates as obtained, for example, from a crystal structure determination. The fragments are composed of a kernel of atoms surrounded by a chosen neighborhood of atoms. The entire molecule is divided into individual kernels and their neighborhoods are added for the individual fragment calculations on the basis of the distances of other atoms from the atoms in a kernel. The hydrated leu1(SINGLEBOND)zervamicin is composed of 295 atoms which could be handled in full by Gaussian 94. The results of the fragment calculations were combined to provide an electron density distribution for the molecule. This distribution was compared with one that represents the distribution obtained from a calculation on the entire molecule at once. The clear implication of this study is that it is feasible to perform ab initio calculations on structures by the use of fragments. The time involved increases essentially linearly with complexity. © 1996 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
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