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  • 1
    ISSN: 1432-2013
    Keywords: Key words Cholecystokinin ; Cysteamine ; Intrapancreatic neuron ; Islets ; Pancreatic secretion ; Pertussis toxin ; Somatostatin ; Somatostatin antagonist
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The role of intrapancreatic neurons in the action of cholecystokinin (CCK) on pancreatic exocrine secretion of the totally isolated, perfused rat pancreas was investigated. Intrapancreatic neurons were activated by applying electrical field stimulation (EFS) to the isolated pancreas for 45 min. When applying EFS, spontaneous pancreatic secretions of fluid and amylase increased until the second 15-min period of EFS and then decreased during the third 15-min period. Atropine (2 µM) notably reduced the EFS-evoked pancreatic secretions of fluid and amylase. The CCK-induced (10 pM) pancreatic secretions of fluid and amylase elevated further in the first 15-min period of EFS and then gradually resumed to the levels observed during application of CCK alone in the third 15-min period of EFS. However, the CCK-induced pancreatic secretions remained elevated even in the third 15-min period of EFS when an action of endogenous somatostatin was inhibited by cyclo-(7-aminoheptanonyl-Phe-d-Trp-Lys-Thr[BZL]) (10 nM) or pertussis toxin (200 ng/ml). EFS further elevated spontaneous exocrine secretion by the cysteamine-treated (300 mg/kg) pancreas, but this was markedly reduced, to normal levels, by infusing somatostatin (100 pM). EFS increased the numbers of immunoreactive somatostatin cells in the Langerhans’ islets. The results indicate that intrapancreatic neuronal activation influences CCK-induced pancreatic secretions in a dual-phase pattern in the rat: an increase during the early phase and a decrease during the late phase. Endogenous somatostatin released from the islets appears to inhibit the enhancing effect of neuronal activation on CCK-induced pancreatic secretion. Of the intrapancreatic neurons, the cholinergic ones appear to predominate in EFS’s effects on CCK-induced pancreatic secretion.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 41 (1998), S. 1133-1151 
    ISSN: 0029-5981
    Keywords: flow control ; numerical solution of Navier-Stokes equation ; Karhunen-Loève Galerkin procedure ; Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A new method of solving the Navier-Stokes equations efficiently by reducing their number of modes is proposed in the present paper. It is based on the Karhunen-Loève decomposition which is a technique of obtaining empirical eigenfunctions from the experimental or numerical data of a system. Employing these empirical eigenfunctions as basis functions of a Galerkin procedure, one can a priori limit the function space considered to the smallest linear subspace that is sufficient to describe the observed phenomena, and consequently reduce the Navier-Stokes equation defined on a complicated geometry to a set of ordinary differential equations with a minimum degree of freedom. The present algorithm is well suited for the problems of flow control or optimization, where one has to compute the flow field repeatedly using the Navier-Stokes equation but one can also estimate the approximate solution space of the flow field based on the range of control variables. The low-dimensional dynamic model of viscous fluid flow derived by the present method is shown to produce accurate flow fields at a drastically reduced computational cost when compared with the finite difference solution of the Navier-Stokes equation. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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